PAPERCLAY FOR LARGE SCALE FORMS allows more

Transcription

PAPERCLAY FOR LARGE SCALE FORMS allows more time for an artist to work
and engage directly. Modelling, carving, changes of mind, surface treatment, and so
forth, may continue at or over the bone-dry stage. Even thin-walled irregular green-ware
paperclay bone dry shapes are easier to handle. The risk of loss to the form pre-fire is
far less because the green strength of a paperclay is nearly double that of usual clay
bodies. Most fractures or accidental damage can be repaired before the first firing no
matter whether the clay is dried out or not. Opportunity to work after the bisque is a
possibility, though the chance of repair success at that stage is somewhat less than it is
over the bone-dry green version. Indeed, if you add enough paper pulp, the final fired
result is also lighter in weight. These benefits give my imagination licence to play. I put
my attention toward what matters in the artwork and the idea itself rather than struggle
with the limitation of traditional clay for projects of large scale. Some visions do not
succeed with a traditional approach or a traditional clay body no matter how much grog,
sand, chamotte or nylon one might be tempted to add instead of paperpulp.
This article win outline ideas that have proven to be the key to the assembly and firing
of large-scale porcelain paperclay sculpture whether it is formed by building up or
carving down. First, I had to be wining to give up a few stubborn habits from using
traditional clay in order to find what worked best and fastest. I wanted alternative
methods to coil building, ways to achieve large thin upright forms in paperclay that
were reliable and consistent with high fire.
With large paperclay pieces, protecting the forms with wet towels or under wraps of
plastic between work sessions hides the structural truth. This habit blinds the sculptor
from learning precisely where and what adjustments will be needed to make. Plus, the
procedure of slow drying so necessary for traditional clay takes more time. Further
ahead, I will explain how the natural shrinkage of paperclay can be the key advantage to
fired success compared with the non-shrink sculpture bodies. Assembly of parts at
leatherhard requires far more time and complication than assembly of the equivalent
parts at bone dry. Most pre-assembled large-scale leatherhard structures are not immune
from movement and warping compared with their equivalents assembled at bone dry.
Better control of movement in the final result and there are more chances to change and
test for secure joins before it is too late.
Paperclay, at bone dry, is water absorbent. Bone-dry work can be dipped in glaze and
still hold its shape long enough for evaporation and uniform glaze adhesion to occur.
Bisque fire used to be the only way to make conventional clay absorb enough water
from the glaze to cause a uniform deposit of glaze on the surface without losing its
shape. Single fire saves time and fuel cost. However, when I do bisque a high-fire
porcelain or stoneware paperclay I take it to cone 04 rather than cone 08. Just that little
difference may save a high pulp thin walled bisque paperclay from accidental crushing
in your hand after fire.
CONSTRUCTIONS WITH POPCELAIN AND FINE GRAINED CLAY.
This article reports results of my experiments to date with both additive (building up
slab construction) and subtractive (that is, carving from a solid chunk) methods with
large scale porcelain and other paperclay sculptures. The first section of this article
explains the results of building about a dozen irregular thickness yet relatively thin
walled (less than 0.2 cm in places) large-scale freestanding work 1.2 m (4 ft) tall from
paper clay pure porcelain slabs with no grog or other refractory added. In addition I
have tested a similar number of works in a ball clay /talc earthenware paperclay.
The second section of this article explains what I learnt about carving down and
modelling large solid chunks of paperclay porcelain at both soft and bone dry states.
Paperclay porcelain combines easily with the light-weight fillers - perlite and
vermiculite - to give an extra textural contrast to the smooth porcelain version. Plus this
perlite paperclay porcelain: (RuffRock) is now a favourite lightweight filler choice to
support thin slabs or weak areas of super smooth paperclay porcelain through to high
fire. For this set of texture work, I was more interested in thickness and compatibility of
Ruff Rock to Pearl bodies at high fire so I have not made made giant works of Ruff
Rock as yet. Perhaps a daring reader will examine giant Ruff Rock in more detail in the
future. New editions of my books about paperclay explain also the sand cast mould and
construction methods I have also been exploring in recent years.
HIGH FIRED PAPEPCLAY SCULPTURE
My early experiments of large-scale tests were high temperature firing of a typical lowfire earthenware body (Rosetta Stone). I constructed a dozen or more earthenware
figures and fired them kiln by kiln. Each one was single fired. I deliberately overfired
these to cone 4 to 6 even though the ball clay/talc (50/50) casting slip body is rated at
cone 04. Without paper traditional earthenware clay structures without any refractory
such as grog, etc, start to collapse at about cone 1 and by cone 4-6 melt drown to a
useless puddle of nondescript stone-like glass. In contrast, my paperclay version of
earthenware (Rosetta Stone) stands tall. The fired result resembles a white stoneware in
hardness and feel at cone 4. At around cone 6 or so, depending on the thickness of the
walls of the form and the even temperature in the kiln, some figures started to slump or
warp. If my approach might work as well for your work, test an earthenware clay for its
suitability for high fire as a paperclay. Those of you who put red iron in earthenware
will have to bring the temperatures down at least two or three cones because the iron
may have a melting effect at temperatures in this range.
LARGE SCALE HIGH FIRE TRADITIONAL PORCELAIN BASE PAPEPCLAY
After success with the low-fire versions of large shapes, I built another dozen shoulder
height forms in my favourite porcelain for trials by high fire. Again, no grog or any
additive other than the pulp was in my base recipe. I planned to put the forms to the
maximum handling abuse and break as many rules of construction as possible to find
the edge of possibility before collapse. I had been humbled by a kiln load of warped
porcelain paperclay in forms overfired during a residency in Bechyne, Czech Republic,
in 1996. Rather than blame the overfired, I wondered what other information could be
gleaned from this loss. Was it the paper? No. Might the warping under stress have
something to do with my assembly method? Perhaps I wanted to sculpt more than I
wanted to align my intention with the natural properties of clay. Paperclay allows me to
assemble at bone dry by a variety of means.
SPECIALTY MIXTURES OF PAPERCLAYS FOR LARGE PROJECI'S
If you are not sure where to start, adapt my recipes for large-scale freestanding
and wall works given here. Test fire, I cannot be responsible for non-standard
materials, events and results clearly beyond my control. I use recycled paper
but I have indicated volumes of pulp by standard toilet roll to help the student
with a starting point for the volume measure of proportion. Uniform dispersal of
the fibre through the clay mass is the key reason wedging pulp in does not work
correctly
Rosetta Stone - Earthenware High Pulp Paper Clay for Sculpture
Cone 04 to 4 normal (maximum cone 6)
Two (2) medium buckets (use same size buckets to measure this) prepared white
earthenware base (rated cone 04-05) or buckets of standard prepared casting slip rated
for cone 06- 05.
One (1) medium bucket (same size) of wet strained bulk of pulp plus or minus handfuls
and inches. Torn paper from 10- 12 rolls of bargain-priced toilet tissue is equivalent to
about eight bulkier rolls of deluxe brands, but don't try to make this pulp in this same
bucket. Use giant barrels, not for beginners to try. Avoid lumps and clumps.
The above is my high-fire low-fire high-pulp all purpose, any kiln, any time, sculpture
recipe for many years.
Texture before firing: Smooth, putty-like. Takes underglaze, slip, engobe, stains, etc.
Texture bone dry: Absorbs water when dipped. Takes underglaze, slip, engobe, stains,
glaze, etc.
Thin walls soften a little when soaked a while. Slakes down overnight or sooner. Sinter
Fired: Carves off in fine powder.
Texture after fire: Smooth, white, the higher you fire it, the more dense and hard the
fired paperclay body feels to touch after cone 4.
Low-fire texture - Cone 03 to 04.. Too hard to carve by hand but use power tool. Can
treat surface with any and all commercial glazes, opaque or transparent underglazes,
overglazes, etc, and refire if desired. Normal slips, engobes, stains work well. At this
temperature, the result is a soft normal earthenware. Vessel will seep water without a
finish gloss glaze or other sealant.
Mid Range (Cone 4 to 6): Hard as a rock. Resembles white stoneware. Resists water but
may not be 100 per cent watertight. Suitable for outdoors in frost and thaw too, glazed
and not glazed.
Substitutions/Adaptation:
Raku: Good anytime- bisque to 04 or more, until you are experienced in fire. When one
knows the kiln, the fuel, the tools, the tongs, how the shapes heat up, and where best to
place them, bone-dry single firing works. China Paint, Gold, Silver and Metallic Lustre,
Decal Fires: cone 032. Best to apply over already fired gloss glazes in multiple Fires.
Base Clay Options: if you substitute an iron bearing red terracotta blended clay as base
for the earthenware base, it fires red to brown. Stick to the recommended lower
temperatures cone 05-02. A heavy red iron concentration acts as a melting as well as
colouring agent. Test first if you fire red iron-bearing terracotta or maiolica-type
paperclay beyond cone 1.
Porcelain Pearl - High Pulp Paper Clay for Sculpture Cone 8 plus
Two (2) medium buckets of prepared porcelain (cone 10) high-fire casting slip.
1 medium bucket of pulp, plus or minus handfuls. (use paper from 10-12 rolls of
bargain-priced toilet tissue equivalent to eight bulkier rolls of a deluxe brand.)
Thin areas become translucent at cone 8. Dare to fire to cone 10 only if walls are thick
enough and other factors mentioned, indicate the structure is stable and built well.
When mixing batches in the studio, avoid or minimise airborne dust clouds. Start with
buckets of prepared liquid casting or pouring slip rather than bags of dry-blended
powdered clay.
Texture before firing: Smooth, putty-like. Takes underglaze, slip, engobe, stains, etc.
Texture bone dry: Absorbs water when dipped. Thin walls soften a little when soaked
for a while. Slakes down overnight or sooner. Takes underglaze, slip, engobe, stains,
glaze, etc.
Texture after firing: Super smooth.
Sinter fire: Carves like soft soapstone, dense, but still easy to handle.
Biscuit fire: At cone 08 may be quite soft, handle with extreme care. Carves like a dry
cosmetic-grade sponge. At higher bisque, cone 03, it will be possible to carve. Does not
slake down in water.
High Fire (cone 8 to 10): Hard as a rock. If thin walled fire to cone 8 and play it safe.
Serious heavy duty power tools are needed to alter the surface at this stage. It would be
far easier to work surfaces before high fire.
Substitutions/Adaptation:
Base Clay Options: If you substitute stoneware throwing clay as base for the porcelain
– paperclay fires tan to brown. Reduction or oxidation atmospheres.
Raku: Good anytime. Bisque to cone 03 or more first. When one knows the kiln, the fuel,
the tools, the tongs, how the shapes heat up, and just where best to place them, bone-dry
single fire is realistic.
China Paint, Cold, Silver and Metallic Lustre, Decal Fires.. cone 032. Best to apply
over already fired gloss glazes.
Ruff-Rock - Gruff-Rock - Porcelain High Pulp
Cone 8- 10 High Fired Texture Body
Two (2) medium buckets (5 gal. / 10 litre) prepared porcelain (cone 10) high-fire
casting slip
1/2 medium bucket of pulp, plus or minus handfuls. (Torn paper from 10- 12 rolls of
bargain-priced toilet tissue equivalent to eight bulkier rolls of a deluxe brand.)
1/2 medium bucket granular perlite, plus or minus handfuls or scoops as needed. Perlite
is found at gardening suppliers and has a good affinity to high pulp porcelain paper clay
and it fires white. The more perlite you add the more crumbly and non clay-like the
body seems, and is. If a lot of perlite is added, the mass has to be packed tightly until it
sets.. Substitute vermiculite if white at high temperature not important. This is a
variation on Porcelain Pearl with perlite added so it is short and fires light too. I like it
for a lightweight ceramic putty filler and in the interiors behind super thin Porcelain
Pearl slab shells for stablilising vulnerable areas of large scale forms. Carves like frozen
chunky peanut butter.
Texture before firing: Short when moist. Takes underglaze, slip, engobe, stains, glaze,
etc.
Texture bone dry. Absorbs water when dipped or sprayed. Softens, then slakes when
soaked over time.
Takes underglaze, slip, engobe, stains, glaze, etc,
Texture after fire: Surface has openings like a coarse utility sponge, irregular granulated
pock marks, lightweight, strong, if fired to the right temperature. Sinter fire: Carves like
frozen chunky peanut butter.
Biscuit fire. At cone 08 the work may be soft; handle with extreme care. Carves more
like a dry kitchen sponge, At cone 03 it is possible to carve. Takes underglaze, slip,
engobe, stains, glaze, etc.
High Fire (cone 8 to 10): Hard as a rock. Serious power tools needed. Gloss glaze to
resist moisture.
Substitutons/Adaptation:
Base Clay Options: If you substitute stoneware throwing clay as a base for the
porcelain-fires tan to brown.
Raku: Good anytime, Bisque to cone 03 or more first. Mien one knows the kiln, the
fuel, the tools, the tongs, how the shapes heat up, and where best to place them, a bone
dry single fire is fine.
China Paint, Cold, Silver and Metallic Lustre, Decal Fires: fire to cone 032. Best to
apply over already-fired gloss glazes.
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Ceramics Today - Porcelain Paperclay by Gaye Stevens
Página 1 de 5
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Articles
An Investigation into the
Properties of Porcelain
Paperclay
by Gaye Stevens
Originally published in Ceramics Technical. Reprinted by permission.
In July, 2000, I began a research project with the
assistance of a Faculty Research Grant from The College
of Fine Arts,University of New South Wales to investigate
the properties and potential of porcelain paperclay.
My studio work is concerned with the vulnerability of being
human, with the dynamics of how we interact as a
community and the consequent processes of acceptance
and rejection. Hence, the juxtaposition of light and shadow
has held significance for me as a metaphor for inclusion
and exclusion. I have been searching for a medium that
will convey fragility and vulnerability but one that also has
a degree of permanence. In early 2000 I had read an
article by Steve Harrison ‘The making of paperclay
porcelain banners’ (Pottery in Australia 37/2 1998 p68-69).
In this article, Harrison describes how he makes paperthin porcelain banners of translucency that can be
imprinted with "tools fingers and objects".
It seemed that this medium had potential for the type of
sculpture I wanted to produce. My aims were twofold.
http://www.ceramicstoday.com/articles/porcelain_paperclay.htm
23/02/2007
Página 2 de 5
Firstly, I wanted to find a way of imprinting thin sheets of
this body with a photographic image to produce a
watermarked effect. That is, I wanted to find a way
(without using any ink), of pressing a photographic image
into the clay body, using some appropriate kind of intaglio
printing plate, in order to yield a heavily embossed image
which when backlit, would produce a photographic
watermark. Secondly, I wanted to explore the potential of
this body for producing 3D forms that would lend
themselves to illumination.
My starting point was his recipe for porcelain paperclay :
l
l
Clay Ceram 50 %
Nepheline Syenite 50%
Add
l
l
l
Ceramic fibre (1000˚C) 8 %
Fine paper pulp 17 %
Water 30%
The clay body is fired to cone 8 in an electric kiln.
The ceramic fibre helps to stabilize the body after the
paper pulp has burnt out at 250ºC and stops the thin
sheets from cracking "along the stress lines created by the
decoration".
The initial process of familiarizing myself with porcelain
paperclay body proved to be not as straightforward as I
anticipated. The result of my first batch was coarse
textured and short, totally inappropriate for holding the
imprint of a recognizable photographic image.
To produce a finer
textured body I
used shredded
ceramic fibre (rather
than ceramic
blanket which I had
used initially, that
had to be
laboriously torn into
tiny pieces) and
mixed it with a
heavy-duty blunger in about four liters of water, until
satisfied with its homogeneous consistency. I mixed the
paper pulp in a similar way and with about the same
amount of water, but I used boiling water this time, to help
break down the fibres. The ceramic fibre and paper pulp
were then thoroughly mixed with the blunger and the other
dry ingredients were added.
The extra water in the mix, which allowed for easier
blending, was removed by heaping the clay on a plastic
tarpaulin and allowing the clear water to run off over a few
days. The resultant body was sticky. I found the easiest
way to work with it was to roll it into slabs between sheets
of heavy-duty plastic.
Photographic Imprints
23/02/2007
Página 3 de 5
Initial trials of imprinting the porcelain body with ceramic
stamps were effective. The clay held the imprint crisply
and I was encouraged to think that a photographic image
would be possible if the right type of ‘stamp’ (plate) could
be found. I had used solar etching plates to produce
photographic etchings in printmaking and thought it might
be possible to use such a plate to imprint the clay.
Unfortunately, the solar plate was unsuitable for this
process because the light sensitive emulsion on the plate
was unable to maintain the sustained contact with the clay
body necessary to imprint it. The emulsion absorbed
moisture from the clay body, expanded and separated
from the backing plate. The resilience of the high cellulose
content in the body also prevented it from being able to
hold the fine imprint to any degree that would produce an
effective image.
In a photographic exhibition of work by Jenny Pollack and
Louis Vidal, entitled ‘Passages’, (Customs House Sydney,
November 2000) I saw embossed photocopies of
photographs that had been produced to make a tactile,
readable surface for people with impaired vision. These
photocopies are produced with a special heat-sensitive
paper which when passed through a PIAF machine reacts
to raise the areas printed with ink to give a kind of Braille
photocopy. With the help of Michael Keighery at the
University of Western Sydney, Milperra, I was able to
produce a photographic 3D image. By using a printing
press, I imprinted this image into a standard clay body and
the imprint was sharp and readable. When I repeated the
process with the porcelain paperclay the resilience of the
cellulose once again reduced the clarity of the image. I
discovered that by allowing the paperclay mix to age (at
least one month), this resilience was reduced and the
readability of the image improved, but the results read
more as a silhouette than a photographic image.
An article in Ceramic Review May/June 2001 presented
research by Helen Smith at the University of the West of
England on the potential of using flexography to emboss
paperclay with a photographic image.
Further inquires within the printing industry led me to a du
Pont product named Cyrel®. This proved to be just what I
was searching for. Cyrel® is a flexible vinyl plate of
approximately 10 mm thickness to which a photographic
image can be transferred by placing a photographic
transparency on the plate and exposing it to intense UV
light. The process duplicates even the minutest detail and
the resulting stamp-like plate will effectively imprint the
porcelain paperclay.
I roll the clay to a similar thickness to the Cyrel plate,
spray the top of the slab with a fine mist of water and
smooth the surface with a plastic ruler. I then leave it to a
dry leatherhard state and use a rolling pin to imprint the
clay with the plate. By drying the imprinted slab slowly
over a few days I avoid any warping. The slab is then fired
slowly on a flat even bed of white silica sand in an electric
kiln to cone 8.
23/02/2007
Página 4 de 5
The fired porcelain paperclay is porous and fragile. As
Steve Harrison suggests, it can be painted with acrylic
medium to give it strength and flexibility and the medium
gives the surface an almost imperceptible luster. Early
results have been most encouraging, to my mind opening
up enormous possibilities for future development.
3D Forms
In my initial attempts to produce three-dimensional forms,
I experimented with various construction and firing
techniques and although the paperclay was effective at
the construction stage, immense care had to be taken
during drying to avoid warping. I found the most effective
construction technique was to work with leather hard or
even totally dry slabs that had been cut to the desired
shape with a sharp blade and to join them with a slightly
drier than normal paper porcelain slip. It was also possible
to roll partially dried slabs into cylindrical forms. However,
during firing, even with meticulously built supports, the
forms warped slightly and although in some cases this
was acceptable, it was too ‘organic’ for the type of form I
wished to produce at this point.
For my purposes, I overcame this weakness by
constructing the forms after firing. In the first instance
where I wanted to convey a sense of precariousness and
tension, and the fragility of sanctuary, I layered the sheets
to create the 3D form. In another piece that addresses the
effort that must go into the construction of sanctuary, I
perforated the edges of the sheets and sewed them
together. The results have been rewarding, to my mind
embodying all the fragility and vulnerability I had hoped to
convey.
Porcelain paperclay while challenging traditional methods
of production, has presented possibilities for my studio
practice. The edges possible with this body, its
translucency and affinity for light, and its seeming fragility
are qualities I intend to investigate further.
Because of the health hazards associated with ceramic
fibre and dry paper pulp, it is essential to use a facemask
and gloves while mixing this body. Mix the clay in an area
with sufficient ventilation and when touching the ceramic
fibre, cover as much of your body as possible with
protective clothing.
At the time of writing, Gaye Stevens was a M Des(Hons) candidate at the
College of Fine Arts, University of New South Wales, Australia. Supervisor:
Jacqueline Clayton.
23/02/2007
Página 5 de 5
Related Links:
How to make Paperclay
More on Paperclay - article by Graham Hay
Paperclay - Links
More Articles
© Ceramics Today
23/02/2007
www.grahamhay.com.au/Ellery1995.html
Página 1 de 3
Reproduced with kind permission by the author Debra Ellery. The articule appeared in a slightly
different form in Pottery in Australia, 1995, (34), 1, 20-21
More articles on paperclay click here.
PROFILE: SOLD ON PAPERCLAY
A look at the recent work of Graham Hay from Western
Australia By DEBRA ELLERY
Paperclay is an adaptive and innovative medium for
the crafts practitioner who is willing to expand
boundaries. It was this versatility as a medium which
attracted Graham Hay initially and he uses it to full
advantage in his work. His purpose is to
communicate and comment upon social issues in a
way that aims to be intellectually and aesthetically
stimulating. Hay's interest in paperclay was
established initially from contact with ceramic
technologist Mike Kusnik during studies at Edith
Cowan University.
Paperclay is particularly useful as a medium
because paper is a constant companion in the
creation and maintenance of organisations and
institutions. Hay's contact with business,
government, education and art establishments have
formed the basis for analysis and comment on the
position of institutions and organisations within the structure of society.
Architectural elements are frequently used by Hay as metaphors for institutions and their
processes. The bell tower which is often found in classical architecture is used in the work
titled "Ancient Tribe". A classic element from a traditional aesthetic is interpreted with
almost whimsical instability. The point Hay is emphasising is that a building is not the actual
institution and it's never as completely rigid as it appears. "Buildings are not the actual
institution and it's never as completely rigid as it appears. "Buildings are not the
organisations, the people are, and they regularly change."
Within our social structure we are frequently defined by the roles
and responsibilies we perform. "Rim to the Centre" comments on
people as individuals, and as a collective, making contact with the
centre. "There is a block on the rim and a block on the tower. I was
making an analogy between the centre, which is a very hierarchical
organisational base, and then the rim outside it. The rim is like
people around us, in some ways they hold us together. It's quite a
fragile structure with tension between those outside and those
within it." This particular work was a major breakthrough for Hay in building open structures,
they are a reference to the individual or groups of people."
A desire to make a structure which had hollow interior
space visible through the external walls culminated in the
work titled "Blooming Bureaucracy". At its base it
resembles classical architecture, a metaphor for
http://www.grahamhay.com.au/Ellery1995.html
22/02/2007
Página 2 de 3
organisation. This structure grows upwards and inwards
leading to an apex where a lone flower blooms. This single blossom is indicative of the
vulnerability of the top position.
Tongues are a provocative metaphor which Hay uses to issue a challenge to "ivory tower"
institutions and organisations. "Argument" is based on an ivory hunting horn. The "ivory
tower" connotes untouchable institutions remote from the real problems of everyday life.
The bright red tongues which scar the outside form indicate a challenge to the language
and words spoken in these institutions.
One of the great advantages of paperclay as Hay sees it, is it allows him to work
spontaneously, or alternatively, gives him the option of leaving work for extended periods of
time, both equally effectively. In the working process Hay employs a variety of techniques.
"Ancient Tribe" was built entirely horizontally, only when it was dry enough, it was turned
upright and supported with bricks. A corrugated mould has been used in some areas of the
structure along with string multi dipped in paperclay and shapes cut from paperclay slabs.
In both "Rim to the Edge" and "Blooming Bureaucracy" he used a pottery wheel and a
scalpel to cut rings of paperclay from slip cast slabs. He further cut and joined these using
paperclay in a squeeze bottle which was diluted to a ration of 1:5. To create the ivory
hunting horn form in "Argument" Hay used a cast slab which was rolled and the surface
scoured with a wire brush. Holes were dug out with a knife to hold the string dipped in
paperclay which forms the tongues.
In discussing his firing schedule Hay emphasises that work can be fired and cooled very
rapidly in the kiln. Delicate work requires rapid firing. If firing thin slabs Hay fires at 250C
per hour to 200C, then 350C to 1100C with a soak of 30 minutes, then he cools the kiln
rapidly. He uses an earthenware slip for his paperclay base.
The influence of place and time is often shown in an unconscious way.
Hay grew up in the South Island of New Zealand and the influence of
place and culture are evident to me in many of his structures. A
resemblance to the traditional Maori food storage structure is evident in
"Ancient Tribe". Traditionally this was a small structure built high on stilts
supports to keep food safe from predators. "Blooming Bureaucracy" could
be based on the parliament buildings in Wellington, nicknamed "The
beehive". The use of the tongue as a challenge is a significant part of the
Maori challenge once known as the "haka". Hay uses the tongue as a
challenge in several of his works.
Hay is a committed professional who throws all of his energy into creating. He willing
expounds the virtues of paperclay to all who will listen. I believe as this medium becomes
more familiar and widely used, many clay practitioners will follow suit.
GRAHAM HAY'S RECIPE
1 Shredded paper soaked in plenty of hot water, blended until pulped.
2 Remove excess water with sieve and sponge.
3 Mix 1/3 pulp with 2/3 clay slip by volume.
4 Pour the porridge-like mixture onto a plaster slab.
5 Keep some paperclay slip aside in a plastic squeeze bottle for use as "glue".
6 Break or cut dry paperclay slabs into desired shapes before building. Stick together
with "glue".
7 Recycle dry scraps by placing them in warm water, leaving for one hour, pour off
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excess water.
8 A few drops of detergent helps prevent the porridge from going off.
9 When working and building with dry clay, a filter mask should be worn.
IMAGES:
Ancient Tribe (1994), Porcelain Paperclay, 55 x 22 x 19 cm.
From Rim to Centre (1994), Earthenware Paperclay, 14 x 14 x 14 cm.
Blooming Bureaucracy (1994), Earthenware Paperclay with plaster base, 59 x 46 x 46 cm.
Argument (1994), Earthenware Paperclay, 45 x 10 x 11 cm .
All photographs by Victor France.
Reproduced with kind permission by the author Debra Ellery. The articule appeared in a slightly
different form in Pottery in Australia, 1995, (34), 1, 20-21
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Reproduced from Farrow, C., (1987) Paper/Clay, Artists Newsletter, United Kingdom, April, p.20-1,
from a copy provided by and with the written permission of the Author.
Paper/Clay
by Carol Farrow
A frequent question during the
one-year Fellow in
Paperworks residency at
Oxford Polytechnic last year
was "What started you making
paper?" My reply "Through
ceramics" often caused
surprise and because I've had
many enquiries about how and
why I use paper, I've written
an article, which perhaps, will
encourage more to try these
techniques.
Although the majority of my
current work is now in
handmade paper, this is
because of a lack of
appropriate firing facilities in
my studio rather than a lack of
desire to use this technique
which I developed whilst
studying ceramics on a post
graduate course at Goldsmiths
College. I would like to take
this opportunity to thank the
Ceramics Department of
Goldsmiths for their bemused
patience in seeing me through
that period of study with the
minimum of fuss even though
they often witnessed books
being packed into their
precious new kilns instead of
pots!
At Goldsmiths, I developed my
own methods of firing paper
and, subsequently, a mixture
of paper pulp and clay which
enabled me to make and
transport very large thin
sheets of clay.
Transient Qualities
This evolved from experiments
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involving the firing of various
materials other than clay. One
of the materials was paper. I
found that paper containing a
high percentage of china clay
(magazine or glossy paper)
when fired to high
temperatures (1300oC), was
transformed to an extremely
fragile ceramic material taking
on interesting visual and
physical properties. I used
paper in the form of books or
magazine stacks, usually
bound with stainless steel
wire to restrain them from
'opening up' during firing, or
enclosed in saggars or under
the weight of kiln furniture.
This transformation of 'books'
was not only departing totally
from the utilitarian aspect of
ceramics but pushing the
limits of non-functional
ceramics, the resulting pieces
being so fragile as to make
handling from kiln to bench
traumatic. However, this
fragility appealed to me, then,
corresponding in my mind to
my preoccupation with the
transient qualities of much of
today's written matter. It gave
more importance to the look
and feel of a 'book' than to its
content.
The book had become an
object with purely visual and
tactile qualities and the
reading (handling) of it altered
and eventually destroyed it.
How often do we read or reread books on our shelves?
How much are they just
symbols, momentos, a visual
catalogue of past
experiences? The element of
change brought about by heat
to these books gave them
another albeit short life, their
own substance taking over
from the printed word. The
finished pieces are not, as
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some critics have suggested,
formed in the kiln purely by
chance, but are completely
controlled by the firing
techniques and the
knowledge of how different
papers react at various
temperatures. It is not the
element of chance but that of
change which is integral to
each piece.
Clay & Pulp
As my work progressed, I ran
out of 'books' to fire and
turned to making my own
paper, giving me another
aspect of control over my
basic materials. I tried
beating/pulping various
papers using a glaze mixer,
and forming them into sheets
in the traditional papermaking
fashion and then began to
add clay slips to the pulp
before forming.
I quickly abandoned the idea
of sheet forming in the
traditional way and opted for a
more direct method. I pulped
ordinary (non china clay)
paper or cotton linters until it
was fibrillated then mixed it
well with a clay slurry
(ordinary clay broken down
well in water), draining off the
excess water. I then spread
this mixture which had the
consistency of soft butter onto
a surface to dry. I often used
a plaster surface which aided
drying, or cast the mix directly
onto a paper or card surface. I
tested different proportions of
pulp to clay and will mention
this briefly later.
I also tried draining the pulped
paper and mixing it with
casting slip then casting in the
normal way to give a lighter
more translucent cast but I did
Book, paper/clay mix cast onto card fired to
1300oC, coloured with oxides.
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not develop this.
I filled large moulds with the
clay/pulp mix and did not
drain them. In this way, solid
casts could be made and fired
which, after firing, were
relatively porous and light.
None of these solid casts
broke in firing but I slowed
down the firing cycle slightly
and the cooling as a
precaution. With the solid
casts a mixture of 75% pulp to
25% clay gave a pitted
surface and was very light
weight. These surfaces were
very receptive to sawdust
firing techniques.
Ceramic Sheets
Using a similar 50/50 mixture,
I found that I could make very
large, thin, flat sheets of
paper/clay which in the green
state had the fibrous strength
of paper and after firing
produced light ceramic
sheets. It was this method
that I used to the greatest
extent in my own work,
casting various surfaces up to
five feet high. I am sure that
to make, transport and fire
such large sheets of clay in
studio conditions without the
fibre content would have been
extremely difficulty. All of
these paper/clay pieces were
fired to the maximum kiln
temperatures in electric or
gas kilns. I would have liked
to have made tests at higher
temperatures but did not have
access to higher firing kilns.
The finished pieces were
fragile but I believe that any
thin sheets of ceramic up to
five feet high would have
been hazardous to transport.
This story has no end, paper fired to 1300oC,
transparent raku glaze, rakud, sawdust fired
pulp/casting slip base.
For the purposes of solid
casting, other additives, such
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as sawdust, worked equally
as well. The real advantage in
the addition of pulp to the clay
was to give fibrous strength in
the forming of large sheets. I
also enjoyed the paper-like
qualities of the fired mixture
and the porosity after high
firing. Another advantage in
adding pulp to the clay was in
cutting the cost of the clay.
Mixture
75% pulp to 25% clay slurry
was the lightest and most
porous/fragile mix.
was less porous but stronger
for larger pieces.
was stronger, heavier but still
a little porous.
Clays that I preferred were
grogged (T Material), or
casting slip (Harrison and
Mayer), but fired higher than
the normal firing range.
Firing
The firing procedure for the
very large slabs was as
follows. The largest kiln was
5' high by 3' wide and deep.
Ideally they should have been
fired flat on a bed of alumina,
but as they had to be fired
standing, I tried several
methods. The most
successful was to build a
staggered support wall of kiln
bricks inside the kiln. The
pieces of paper/clay were
stood upright against the kiln
bricks. If several pieces were
being fired together, a thin
layer of ceramic fibre was
placed between each piece.
Finally an enclosing support
wall of kiln bricks was
constructed. Both walls were
built leaving gaps for heat to
circulate. The firing cycle was
Kiln brick support wall in 5' high kiln.
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normal to 1300oC except that
at about 250oC smoke was
given off from the pulp. This
lasts for 10-15 minutes
depending on the quantity
being fired therefore an
extraction system is
advisable. I did not find the
smoke detrimental to the kiln
in any way or to other 'normal'
clay work in the kiln. There
was some sagging and
distortion in large sheets if
gaps between the support
system allowed movement. If
smaller pieces could be fired
flat on a thin bed of alumina,
this was least problematic and
time-consuming.
Because the pieces were still
porous after high firing it is
possible to apply washes of
oxides or glaze before
refiring. Colour can be added
to basic clay/paper mix by
adding oxides or glazes
directly to the mixture before
firing.
A touring exhibition of Carol
Farrow's Paperwork and
Paper/clay will begin at South
Hill Park Arts Centre,
Bracknell on Aust 22 until
September 27 moving on to
West Surrey College,
Farnham and Portsmouth City
Museum and Art Gallery. The
Paperworks Fellowship was
based in the Design
Department of Oxford
Polytechnic in the Paperworks
Mezzanine, an offshoot of Ivor
Robinson's 'Bookworks'
Course.
Paper/clay pieces separated by ceramic fibre
(large kiln props were removed before the final
enclosing wall was built).
Reproduced from Carol Farrow, (1987) Paper/Clay, Artists Newsletter, United Kingdom, April, p.20-1,
from a copy provided by and with the written permission of the Author.
Read more journal articles here
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Reproduced with kind permission from Brian Gartside. This article appeared in a slightly different
form in New Zealand Potter, No. 3, 1993, 32-33.
BACK
... mix WHAT with CLAY?
By BRIAN GARTSIDE
Cellulose fibre is a hollow tube-like structure which is an essential part of all plants and
trees. It plays an important part in photosynthesis and osmosis. It has an amazing ability to
syphon moisture into itself, acting like a sponge. Different sources give a variety of fibres,
the length and size of which depend on the type of tree or plant producing them. An easy
source of fibre for the potter can be found in any man-made paper. This can be torn into
shreds and soaked in hot water, usually all that's necessary to break it down, but for extra
speed an electric drill fitted with a mixing blade is useful.
Shorter fibres which form the basis of tissue, blotting paper and newsprint are excellent. So
is computer and photocopier paper. All these break down easily in hot water. If you can
afford it, pure cotton and linen papers used by artists are best as they have a marked
absence of lignin, a complex polymer associated with cellulose. Being a cell wall stiffener,
lignin is water resistant and can affect the amount of water needed to soak the paper.
Cardboard is best avoided as it contains glue and also shiny papers which contain kaolin neither of these break down easily in water. A good test of whether a paper is suitable, is to
see how it tears - the more easily it tears, the shorter and more suitable the fibres it
contains.
Under magnification clay particles are tiny compared with cellulose fibres. When clay slip
and paper pulp are mixed together the platelets of clay are easily syphoned into the fibre
tubes. The resulting complex network of fibre and clay slip gives the mixture important and
unusual working characteristics of benefit to potters and sculptors.
Other materials such as nylon, fibreglass and sawdust have been mixed with clay, but
nothing compares to paper pulp in its effect. Paper fibres give a non-smooth slightly spiky
surface which further enhances its binding qualities. One very unfortunate disadvantage
compared to nylon or fibreglass must be admitted - after about a fortnight it begins to
SMELL! To avoid the decay of this plant matter, the pulp could be mixed as needed, or
stored in plastic bags in a deep freeze.
Any clay can be used. It needs to be mixed well until smooth and creamy. A deflocculant
can reduce the amount of water and subsequently the time needed for evaporation and
drying. A quick and convenient clay therefore, is casting slip, though personally I find this
an excellent way to use the slops and trimmings from my potter's wheel.
Can you use the material on the wheel? The answer for me is no. I can't throw this clay on
my wheel, neither can I wedge it.... but some people claim they can....
So what's all the fuss about?
• It's virtually impossible for large cracks to develop as the clay dries.
• Layering on dry slabs will not warp.
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• Excellent for layering in plaster moulds.
• Works well for coiling technique.
• Joining pieces can be done at any stage - dry to wet to leatherhard all join well.
• As the material dries it develops unbelievable tensile strength.
• Fired and bisqued pieces can be embedded into the soft slip.
• Ceramic pieces can be bigger and stronger and up to 50% lighter in weight.
• Behaves exactly like clay in the firing process - it IS clay.
• Can readily be pour-moulded. Who needs a slab roller any more?
Notes on the Photographs
1. Hot water, tissue, copier paper is soaked and beaten with an electric drill mixer blade. Be
generous with the water, more than you think!
2. The pulp is poured into a sieve and then squeezed by hand to remove most of the water.
3. Pulp dropped into clay slip. Use volume ratio from l0% to 50% paper pulp. A ruler
simplifies measurement of volume.
4. Porridge consistency. Thoroughly mixed by hand, stick or mixer blade, the clay now
looks like oatmeal porridge. Poured onto a dry surface or plaster slab.
5. Paddled and plastered with a knife or flat stick to any thickness. Thin edges show the
fine fibres.
6. Poured into a frame or mould the material lends itself to any shaping method. Can dry
overnight.
7. Wet paper/clay slip can be added to dry without any problems, smoothed or textured to
taste.
8. Thin and thick can be combined in one slab.
9. Hard dry slabs can be scoured with a sharp knife and snapped over the edge of a table.
The cellulose fibres are just visible to the eye.
Acknowledgements:
I am indebted to lbrabim Wagh of London who worked with me for ten weeks at Banff
Centre for the Arts when we were resident artists in 1991. Rosette Gault of Seattle who was
also a resident artist at that time, continued researching the material and published her
booklet Paperclay for Ceramic Sculptors this year. I used her findings extensively in my
work and in this article.
BRIAN GARTSIDE Runciman Rd, Pukekohe R.D.2 New Zealand Ph: +64 9238 2393
Website: www.gartside.info
To read Part II of this topic, dealing with forming, firing and glazing, click here.
Point at images with mouse to read notes.
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Reproduced with kind permission by Brian Gartside. This article appeared in a slightly different form
in New Zealand Potter, No. 3, 1993, 32-33.
BACK
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Página 1 de 3
More paperclay articles? click here.
SUITCASE ART
Travelling Light
Brian Gartside demonstrated the potential of paperclay when he was a guest at the
International Potters' Festival, Aberystwyth, Wales, 1993. This is Part II of his article
on paper/clay. To read Brian's first article on making paperclay click here.
Those of us involved with pottery as a living are continually on the look-out for sales
possibilities. Suitcase Art was a phrase enjoyed by English potter John Pollex and myself
in a conversation a few years ago. It refers to making high-value ceramics that would travel
easily around the world, and would of course, be in high demand.
I witnessed the ultimate in Suitcase Art when the American potter Ron Nagle brought a
very small suitcase to his slide talk, opened it and set up a miniature exhibition on a table in
front of his audience.
This concept of Suitcase Art was then further expanded by the guest demonstrator at the
International Potters' Festival in Wales, 1993. He opened a large suit case on the stage and
told the audience the four slabs of clay he pulled out, had travelled half way around the
world, surviving airline baggage handlers in Auckland, Los Angeles, Seattle and Heathrow
airports. He revealed that these slabs were unfired and proceeded to wave and jiggle them
up and down whilst holding them between fingers and thumb at the very edge of the 60cm
long slabs. They did not break, though they seemed to bend slightly as they were handled
in this way.
During the hour or two of his demonstration he assembled a rectangular box which
consisted of bone-hard, leather-hard and sloppy paperclay. Imitation straps and buckles
were modelled wet onto the dry surface. A pre-made stiff handle was then attached with
scoring and paper/clay slops - voila! A clay suitcase! To the amazement of the audience he
then lifted the suitcase by the handle after only half a minute and was able to walk around
with it totally intact!
Quite simply, paperclay has the ability to stick to itself and be really strong no matter how
dry or how wet. It is possible to join anything of any thickness, at any angle, at anytime,
using paperclay slip as a glue. It will also join easily to ordinary clay. It seems that nearly all
rules of clay making can be broken.
My preference is to make slabs on a dry plaster slab with a mixture of clay slip and 30 50% paper pulp. For large amounts of paper pulp a conversation with a maker of
handmade paper would be helpful. They have ways of making paper pulp and also use
linters, a readymade source of cellulose fibres. Any clay slip can be used, but I find a
readily accessible source from my wheel slops and trimmings which are easily soaked
down.
lf clay is removed as slabs from the plaster the following day, these can be rolled into tubes
of any diameter for future construction. Or it can be scraped away from the plaster while still
wet and mixed by hand into a plastic state. Coils can then be made or wheel throwing
attempted. Whilst in the slop state it can be spread or poured into moulds and left to dry
out. Objects do not have to be made hollow.
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I leave my slabs to go bone-dry on the plaster slab. They do not warp and I am able to
stack them on edge for storage and future use. At first it seemed that all my ideas wore
limited to straight, flat-sided forms once the slabs had been made.
Recently I decided to re-soak a paperclay slab by totally immersing it in water in a shallow
tub, leaving it for at least three hours. The clay and fibres re-absorbed water until the large
slab became flexible enough to wrap around into a shape. If a slab is left in water overnight
it becomes very sloppy at the surface, but still holds in one piece and is extremely flexible.
So it appears the material can be dried out and wetted many times without ill effect.
Hard surfaces can be plastered and modelled on with more sloppy clay. Fired or glazed
ceramic objects and bits of any kind can be pressed into thick paper/clay while it is still wet.
It all dries together without the cracking usually associated with shrinkage.
Texture is easily controlled too. If left to itself, the paper/clay dries with a characteristic
lumpy porridge surface. At any stage this can be smoothed with a very fine sponge or,
depending on the water content, with rough sandpaper or file. Imprinting works well, but
carving is definitely hindered by the cellulose fibres clinging to each other in the mix.
Firing. Special considerations are recommended if bisque firing is done in an electric kiln.
The paper fibre starts to burn away at300O and can fill the studio or kiln shed with
unpleasant fumes. This smoking can continue up to 500OC. It's important to fire slowly
during this period - between 5OOC and 75OC per hour- and to fire with vents and door open
if possible. The room should also be well ventilated. There is not the same problem when
firing with wood, oil or gas, as the fumes depart up the flue. Once the paper is burnt away
the firing can continue as normal.
After bisque firing the appearance and texture are normal in everyway. The fired clay looks
and acts as clay always does. The minute spaces formerly occupied by the cellulose fibres
cannot be seen by the naked eye and the only noticeable difference will be a lightness in
weight, especially when the mix is 50/50, paper to clay.
Glazing can proceed as it always does - the fibres are gone and play no part in the ceramic
process. Any glaze can be used and the results will be as brilliant or depressing as they
always are. Salt fire, raku, reduction or pit firing can proceed as normal.
The slab roller could become an endangered species - on the verge of extinction.
Watching people work with this material is enjoyable. Hands covered in 'sludge', they can
be so adventurous - joining and building with little or no technical skill. None of the ordinary
clay rules apply at the construction stage. lifting and moving work is less of a problem and
breakages seldom occur.
This can open up the mind to structures and forms that flow in a natural way, especially in
the sculptural area. A bold, adventurous approach with seemingly impossible assemblages
can be tried. Fragility is a thing of the past with structures remaining strong though its
pieces may be arranged and re-arranged many times.
Paper/clay offers endless possibilities. Information on this topic is only at the beginning
stage, with new methods and discoveries emerging weekly.
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Top row: Storing paperclay as bone-hard rolls, tubes, slabs and also crushed waste ready
for recycling.
Row two and three: The working of wet and hard, dry pieces together. Last photo
demonstrates a joint defying breakage and gravity.
Last row: The paperclay slip being roughly cast into plaster moulds, and coiling. The final
photograph shows shards and other ceramic material pressed into the clay.
Photographs by Brian Gadside.
Reproduced with kind permission by Brian Gartside. The article appeared in a slightly
different form in New Zealand Potter, No. 1, 1994 17-18.
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A Complete copy of the journal article.
THE MAKING OF PAPERCLAY
PORCELAIN BANNERS
By Steve Harrison
Paperclay can be used to make sonic excellent tiles. Very thin and translucent porcelain
paperclay tiles, or what I call ceramic banners, can be made up to 900 x 600 mm, by 1 mm
to 1.5 mm thick. Yes, read my type, 1.5 mm. thick! using the following recipe and technique.
The standard translucent porcelain
bodies I found to be disappointing
and did not work well. So I
developed the following body
specially for this purpose. Having
tried many different variations, this
is the most successful recipe so far;
Plastic White China Clay 1500 g
Nepheline Syenite
1500 g
Ceramic Fibre (100OoC) 250 g
Fine Paper Pulp (dry)
500 g
Water
4.5 litres
The china day I use is 'clay ceram',
and the ceramic fibre doesn't seem
to matter, I tried all three grades
and couldn't notice any difference
between them, so I use the
cheapest which is 1000'C L T Batt.
The paper pulp is a dry shredded
material used for home insulation. I
bought this from 'Cool n Cosy'
home insulation in Sydney. There
are two types, The finished product
has poison added to deter rats etc.
for use in houses, but it is possible
to obtain untreated material before
it has gone through the final
process.
Measure the water into a plastic bucket, weigh out the ceramic fibre and dunk it into the
water. Because this is a clay making exercise, you will already be wearing your dust mask,
but rubber gloves are also advisable when handling ceramic fibre. Lift the ceramic fibre out
of the water and tear into small shreds, dropping them back into the water. Break up the
shreds of fibre into a fine liquidised pulp by vigorously mixing with a paint stirrer attached to
an electric drill. Now add the finely shredded dry paper pulp, whisk into the finely shredded
fibre liquid until all the paper is wet. Now add the clay and syenite, stir until evenly mixed
and there are no colour variations. The result should be a soft plastic paste.
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Using a light weight cellulose/cement batt as a backing, spread a jumbo garbage bag over
the batt, held in place with paper clips. Spead a layer of paper clay mix fairly evenly over
the plastic sheet with a spatula. Place another sheet of plastic garbage bag over the top
and roll out the clay in all directions with as much pressure as you can muster until it oozes
out off the batt on all sides. Alternatively, the batt can be placed on the slab roller and
reduced in that way. Keep rolling until it is as thin as you can get it.
Impressions can be applied through
the thin plastic sheet with tools,
fingers, and objects or the top plastic
layer can be peeled off and marks
made directly into the clay surface.
The resulting tile or banner can be
left to dry slowly overnight or left in
the sun and wind in which case it
may curl a little at the edges but will
be- dry in an hour or two. it can be
picked up by its plastic sheet (it is
remarkably flexible) and laid in the
kiln upside down so that the plastic
sheet can be peeled off. It can of
course be placed in the kiln with the
plastic still attached, and it will bum
away during firing, but the gases
produced from burning plastic are
ozone damaging.
Firing is to Orton Cone 8 in 4 to 8
hours, depending on the decoration.
If the marks are many and vigorous,
a longer firing is required to stop the
tile splitting up along the incisions. This is why the ceramic fibre is added, as it doesn't bum
out like the paper but persists. The paper does a sterling job at room temperature of binding
the surface together but the tell tale waft of smoke at 250,C spells its end, and that is when
the normal paperclay tile will crack if the fibre isn't added, as the fibre remains intact until
elevated temperatures resisting any tendency in the tile to crack apart along the stress lines
created in the decoration. Eventually the ceramic fibres dissolve into the ceramic body
glass, which is created by the high proportion of nepheline syenite in the recipe.
The finished banner is quite fragile if it is only one millimetre thick, which is not
unreasonable. When removed from the kiln I strengthened and reinforced it by saturating it
with clear vinyl acrylic artists medium and coating it on either one or both sides with tissue
paper, again saturated with clear vinyl acrylic artists medium. This gives the resultant finish
a remarkable parchment like quality. The surface feel is dry with a hint of absorbency that
creates an impression that it will almost stick to your fingers, but it doesn't. A feeling of
absorbency from something that you know is vitreous, glassy and translucent, yet can be
mistaken for paper in not just look but feel, is fascinating, if not confusing. The juxtaposition
of knowledge and perception clashing. What is known to be ceramic, in fact porcelain, and
all that that entails, pitted against what is clearly perceived to be parchment or blotting
paper is intriguing. This is augmented by the fact that these posters, banners, panels, tiles
are quite flexible and can be bent 75 to 100 mm. from their original straight form This can
produce a noise that Rolf Harris would be proud of.
What appears to be a rigid and fragile gossamer of mixed messages and perceptions
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somewhere between porcelain and parchment, as it transpires is a quite flexible entity,
which beyond all expectations is remarkably robust. I dropped a piece two and a half
metres during hanging at one show and it bounced, luckily having landed on its edge which
carried the shock of the impact well. However, one piece was successfully vandalised by a
king-hit from a child at another show. I've had my disasters, but after all, its the combination
of the tactile and the visual that make this technique so appealing. Its perceived fragility
gives it an edgy visual presence but this is eventually tempered by the acceptance of actual
resilience. I have made a point of always installing these pieces at chest height so that it
will facilitate, even encourage exploration of their qualities.
My thanks to Jane Calthorpe of 'Paperclay Ceramics' for advice and inspiration.
Reproduced with kind permission by the author Steve Harrison (Email 7/10/2001 6:40 pm).
The article appeared in a slightly different form in Pottery in Australia, 37, (2) 68-9. 1998.
22/02/2007
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USING PAPER FIBRE AS A SUBSTITUTE IN CERAMIC CLAYS
By Leena Juvonen, Finland.
Paperclay is combination of cellulose fibre and clay.
Compared to conventional clay bodies it has better
greenstrength and is lighter in weight after firing.
Substituting part of the clay with paper fibres creates a
new kind of material, which makes it possible to build
large, thin objects without cracking.
Essential tests in this study has been bending strength,
porosity, shrinkage and bending in firing. Material tests
have been carried out on different kind of fibres like
cellulose, waste paper and sludges from paper mills.
Along with material tests there has been also included artistic part in which has been tested
paperclay in practice. Large, thin bowls and slabs has been made by pressing on plaster
moulds and painted with ceramic pigments. The aim of this research has been to improve
handling properties of clay in green stage.
1. INTRODUCTION
In making large ceramic objects, the plastic properties and weight of the material have
traditionally limited modelling possibilities. Fragility and shrinkage in the green state have
been frequently encountered problems with conventional claybodies. Clay reinforced with
paper fibre, however, is an excellent material for large pieces, sculptures and slabs,
because of its remarkable green strength and lightweight. In paperclay, the clay particles
glue the paper fibres into a network and thus form a supporting structure for an unfired
object and prevent cracking. The paper fibres burn away from the clay in firing, leaving the
object porous.
Use of paperclay is economical. Instead of requiring new paper, all kinds of waste paper,
recycled paper and pulp are good material to be mixed with clay. Material and energy costs
are cut down as paper fibre added to clay body fills up the clay mass and contributes its
heat value to firing (1). Paperclay also lasts rapid temperature changes, which shortens the
firing time and saves energy.
The capability of cellulose fibre to absorb water is an essential advantage to claybodies in
plastic state. Being hollow, cellulose fibre is very absorbent and withstands compression
and twisting. Since clay particles are much smaller than fibres, they are absorbed to the
surface of the fibre as the clay dries. The rough surface enables the fibre to be attached to
the clay tightly enough so as not to slip from its hollow cavity.
Since the benefits of paperclay in comparison to conventional claybodies lie in its strong
green strength and light fired weight, essential research issues have been bending
strength, porosity and shrinkage and as bending in firing. The strength of paperclay is
determined by clay composition and the paper fibre type, as well as the relationship
between fibre amount and quality. Also the production method and firing temperature is
significant. The purpose of this series of experiments was to study how much the fibre type
affects the strength of the claybody and firing strength. The tests were carried out in
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cooperation with Helsinki University of Technology, and Finnish paper mills contributed with
paper fibre samples.
The starting point of this study was the research on paperclay as sculpting material by
Rosette Gault, of USA (2). Beside the material study, an artistic part is included in this
study, where the practical applications of paperclay were tested. The firing temperature of
1100oC was focused, since the pieces were painted with ceramic pigments, some of which
are burned off at higher temperatures.
2. ULTIMATE BENDING STRENGTH
The objective of this study was to find a paperclay composition where the fibres would yield
strong green strength and where the porosity created by the fibres in firing would be
smooth, delicate and evenly spread. In other words, the fired clay is lighter than the
corresponding pure base claybody without sacrificing and technical properties essential.
Paper and cellulose were reduced to pulp before mixing into the claybodies. The paper was
first soaked in hot water and beaten to disintegrate the fibres. The excess water was
squeezed out by using a large mesh screen to get a pulp with approximately 20 percent
water, where the clay was added. The ratio of fibre varies from 2%, 10% and 20% of dry
fibre in relation to the dry weight of the clay.
From the test material, 22 test batches were prepared: with seven different fibre types,
three different fibre ratios and a base claybody with no fibre added. Ten test bars, each
measuring 25 mm x 25 mm x 150 mm, were made of each test batch by pressing into a
one-sided plaster mould. The clay was pressed by hand and the open surface was
smoothened with a splint. The tests were repeated five times with both unfired pieces and
pieces fired at 1100oC.
The tests were made at the Helsinki University of Technology at the metal laboratory with
Zwick 1385 drawing engine as three point bending fatigue test, where the test bars were
bent at a speed of 2 mm/min. The measurement method was adapted according to ISO
3327-198(E) specification. Test materials were different fibre types, selected for being
easily available: waste paper, pulp, and rejects that develop in the paper manufacturing
industry. The clay bodies were all earthenware.
Composition of clay body and paper fibre types.
Base clay body Ml
Fibre types
25%: Ball clay Hyplas 71
A: Pulp reject
25%: Kaolin Grolleg
B: Ground wood pulps reject
10%: Silica
C: Fibre recovery concentrate reject
10%: Feldspar
D: Fluting board
30%: Calcinated kaolin
E: Bleached pine sulphate
F: Bleached birch sulphate
G: Shredded paper
H: Base claybody Ml
Table 1 Ultimate bending strength of unfired and fired test bars N/mm2 with varied
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fibre contents.
unfired
fired
fibre content
2%
10%
20%
2%
10%
20%
Pulp reject
1.8
1.4
0.8
19.4
7.0
2.5
Ground wood reject
1.8
1.5
1.0
16.8
5.9
2.2
Recovery concentrate reject
1.2
1.9
1.0
15.4
7.5
1.8
Fluting board
1.4
2.1
1.2
19.3
9.0
1.7
Pine sulphate
1.8
1.5
1.0
17.8
7.6
3.2
Birch sulphate
1.6
1.5
0.9
18.4
10.0
3.2
Shredded paper
1.8
1.6
2.6
20.6
5.3
6.8
Base claybody Ml
1.0
24.8
Table 2 Bending flexure of unfired test bars in millimetres with varied fibre contents.
2%
10%
20%
Pulp reject
0.8
0.6
0.7
Ground wood reject
0.7
0.8
1.1
Recovery concentrate reject
0.5
0.9
1.0
Fluting board
0.4
0.9
0.8
Pine sulphate
0.8
0.8
1.0
Birch sulphate
0.5
0.8
1.4
Shredded paper
0.8
0.8
1.4
Base claybody MI
0.2
The bending flexure of unfired paperclay batches with resistance to breaking strain
increases manyfold with all fibre types in comparison to that of pure clay. Even with a small
ratio of 2% fibre, up to a fourfold bending flexure can be reached. A greater fibre content
(10 or 20%) will improve bending flexure with most fibre types but the effect is not any
longer remarkable with all fibre types. The best effect was achieved by adding 20 %
shredded paper. Also the green strength is improved by adding fibre almost to a double to
that of pure clay. However, a fibre ratio exceeding 2% did not generally improve, but
reduced the strength rating. The best result was obtained by adding 20% waste paper.
The strength of the fired test bars reduced with all fibre types in comparison to pure base
claybody. An increase in the fibre content further reduced the strength rating. Ultimate
bending strength fell down by 17% with a 2-percent ratio of the fibre with the best rating at
each point. With a ratio of 10% fibre, the decrease was 60% and with 20% it amounted to
73%. After pure base claybody, the best result was reached with a ratio of 2 % waste
paper.
The strength and bending flexure rates were affected by how evenly the paper fibre was
mixed into the clay, which varied among the test bars. Since the defects were related to
production technology, making the bars differ from each other, the defects influenced rather
the general strength level than that between the test pieces.
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Since the aim of adding fibre was to improve the plastic properties of the clay in green
state, the bending flexure was of great importance. A large, thin piece must endure its own
weight at all stages of production. The more the clay withstands warping in green state, the
larger and thinner the piece can be.
The test results show that a crucially better bending strength and tensile strength was
yielded with all fibre types than that of pure base claybodies. However, the fired strength in
turn decreased. It can be concluded from the results that the fibre type does not have as
essential an effect as the ratio of adding it to clay, when aiming at the best possible green
strength without reducing the fired strength. Moreover, the properties of the base claybody
and vitrification degree have a crucial effect.
3. POROSITY AND SHRINGAGE
Waste papers often contain traces of clay and filling agents, mainly kaolin. For this reason,
it must be taken into account that inorganic substances may affect the vitrification of the
voids left by the fibres. A large content of paper fibre can raise the vitrification temperature
of the clay in case it contains lots of trace minerals (3). The higher the ratio of paper fibre,
the lighter and more fragile is the fired result.
As the clay is vitrified, the piece shrinks and the voids left by the fibres are filled up.
Consequently, the vitrification level will essentially affect the-fired strength. The impact of
the fibre type to the porosity and shrinkage was studied. The test batches were prepared in
the same manner as with the bending fatigue tests. From slabs pressed on plaster bats test
pieces with the dimensions 40mrn x 70mm x 5mm were cut and fired to 1100-1250oC in a
gradient kiln where seven different temperatures with an interval of 25oC can be used
during the same firing. The porosity and shrinkage rates were studied through measuring
the water absorption of the test bars.
Pieces were made from different paperclays. The practical experiments showed that when
earthenware is mixed with paper pulp, the strength of thin objects is not sufficient in the
temperature of 1100oC. The claybody used in bending fatigue tests was therefore replaced
base claybody no 3 containing ball clay and talc and having a lower firing temperature
(1100oC). Moreover, the ratio of fibre was changed to correspond the strength level
required by green strength and fired strength. The claybodies were mixed with 7% of dry
fibre in relation to dry weight of the claybody.
Table 3 Porosity and shrinkage with base claybody 3 and a paper fibre ratio of 7% in
seven temperatures.
A
B
G
H
I
J
K
Water absorption
1100oC
28
32
26
16
27
16
29
1125oC
26
28
21
13
24
5
25
1150oC
21
23
14
8
18
47
21
1175oC
13
16
7
1
9
12
1200oC
10
11
1
0
4
11
1225oC
9
9
1
1
2
9
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8
9
1
0
2
10
0
0
3
1
1
0
1
1100oC
3
1
4
4
4
7
3
1125oC
4
3
6
6
4
9
4
1150oC
7
6
9
9
7
7
6
1175oC
9
9
11
13
10
9
1200oC
10
10
14
13
11
11
1225oC
11
10
13
14
13
10
1250oC
10
11
14
14
13
11
Shrinkage (drying)
Shrinkage (firing)
Composition of clay body and paper fibre types
Base claybody 3
Fibre types
45% Ball clay Hyplas 71
A Pulp reject
35% Talc
B Ground wood pulp reject
20% Calcinated kaolin
G Shredded paper
H Base claybody 3 with no fibre
I De-inking reject
J Cotton linters
K Fluffed sulphate pulp
L Liner board
4. BENDING IN FIRING
The firing temperature is significant to fired strength of a thin paperclay object. The clay
should be vitrified as thoroughly as possible without warping the object. Once the voids left
by the fibres start to fill up in firing, the form is easily warped. With the same test batches of
which the porosity and shrinkage was measured also the bending in firing was measured
with three different temperatures: 1120oC, 1160oC, and 1200oC.
Test pieces with the dimensions 40mm x 5mm x 150mm were prepared by cutting from
slabs pressed on plaster bats. The test bars were placed on a V-shaped base, supported at
both ends. After firing each bar, placed horizontally had bent and also shrunk in the middle.
Each bar was then removed from the base and its exact profile was drawn on scale paper,
from which the bending in firing was calculated.
Table 4 Bending in firing with base claybody No 3 and a fibre ratio of 7%
Bending in firing (mm)
A
B
G
H
I
J
K
1120oC
2
6
9
5
3
6
6
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1160oC
1200oC
5. PRACTICAL APPLICATIONS
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13
9
19
5
9
11
10
18
20
23
13
18
15
19
Beside the material study, objects were produced to test the properties of paperclay in
practical applications. This way information was gained on the plastic properties of the
paperclay in green state as well as its capability to maintain the form intact in firing. Since
sufficient green strength can be achieved with all paperclays, the selection of fibre type is
affected more remarkably by how easily [available the fibre can be found].
[The b]ending flexure of unfired objects is slightly stronger but the fibres tend to build [more]
easily while pressing to a plaster cast. Additionally, the thickness of the fibre [in the clay]
affects the plastic properties of the clay. Fibres from hardwood having long [fibres] with
thick walls are intertwined and build clots more easily in moulding stage [compared to]
fibres from softwood that are short and thin-walled. These short fibres are [covered] with
small fluffs to which the clay particles will be affixed well.
On the basis of the knowledge gained from the material study, several modelling [methods]
were tested. The aim was to find suitable working methods for large thin [objects].
Paperclay can be hand built as well as cast or pressed into mould. However [it differs] from
conventional claybodies: while being more un-plastic, it remains plastic [longer] in plastic
state, making it difficult to have large three-dimensioned forms [maintain] their shape
without a supplementary mould. To make compact objects from [this] material, a mould is
required.
Paperclay has a tendency to attach to a plaster mould tightly, especially with claybodies
having a high fibre ratio. Talc was applied to the surface of the mould to make it easier to
remove the object from the mould. As the drying shrinkage is smaller with paperclay than
with conventional claybodies, the clay should contain enough water and plastic substances
to make the object shrink sufficiently to be taken out of the mould. Otherwise removing thin
objects without breaking is problematic.
Leena Juvonen 1994, paperclay bowl, 65cm x 6Scm x 20cm, painted with ceramic
pigments
With paperclay, it is easy to produce large surfaces, which makes it a natural material for
paintings made with the methods of ceramics. The objects were painted with ceramic
pigments in green state. A smooth surface was attained with a plaster mould on which the
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paintbrush ran smoothly. By pressing to mould, large thin objects bowls and slabs were
made. The light weight of the paperclay allows a rolling shape where the round bottom
touches the ground only at a couple of points. The bowls were fired on the thin brim
whereby the arched structure was able to bear the weight of the material. The slabs were
pressed on a plaster bat and their surface rolled tight.
Working with paperclay is more spontaneous than with conventional clay bodies. Paperclay
lasts quick drying and firing without cracking or warping. The objects were left to dry
overnight on the top of the kiln without a plastic cover and taken out of the moulds in the
morning when dry. Thin paperclay objects need not be bisqued. Instead, they can be fired
directly to the final temperature, since they are very fragile as the fibres have burned away,
but the clay has not yet vitrified. However, paperclay endures bisque firing, too. Unfired
paperclay absorbs glazing to itself, making the surface compact and improving the fired
strength at the same time. Raw glazing also softens the colour surfaces. Thanks to the
reinforcing fibre, a glazed, wet object can be safely transported to the kiln and firing can be
started when the object is still wet.
Paperclay questions traditional restrictions prevailing in ceramics. Use of fibre improves the
plastic properties of the claybody, and gives more creative freedom, from which novel ideas
can be brought about. One of the practical applications of paperclay could be e.g. elements
for interior decoration where fire-resistant light materials are required.
REFERENCES
(1) Zani, Tengalia, Panigada, Re-use of Paper-making sludge in brick production, ZI
1211990
(2) Rosette Gault, Paperclay for ceramic sculptors, Studio companion, Seattle WA, USA,
1993
(3) Rosette Gault, Second-generation ceramic sculpture technical and aesthetic potential of
paperclay, Interaction in Ceramics, UIAH, Helsinki, 1993
Paper presented and published at the 8th CIMTEC World Ceramics Congress, Finenze,
Italy June 1997. Reproduced here with kind permission from Leena Juvonen, Kaapakuja 16
A, 00760 Helsinki, Finland
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SLIPPING INTO PAPERCLAY
A Research Paper by Andy Miller (1994)
Introduction
Paperclay, although not new in the ceramics world, has in the past few years been
recognised as an extremely versatile medium. The growing popularity and number of artists
using paperclay has of course led to new methods of employing paperclay in the sculpture
process. I therefore considered it very fortunate timing that while doing a slip-casting course
I was introduced to the astounding qualities of paperclay compared to normal clay
materials. Slip casting is a well-understood process where a plaster mould is made from a
clay master and thereafter many copies can be made. It required no great leap of logic to
combine slip casting with paperclay and the result combines the precision of the slip cast
shape with the flexibility of paperclay.
Properties of Paperclay
Paperclay's success lies in the interaction of the clay body and fibre at a microstructural
level (figs 1 & 2) as Brian Gartside explains in New Zealand Potter, Vol 36 No, 1, "Cellulose
fibre is a hollow tube-like structure which is an essential part of plants and trees.... It has an
amazing ability to siphon moisture into itself, acting like a sponge. Under magnification clay
particles are tiny compared with cellulose fibres. When clay slip and paper pulp are mixed
together the platelets of clay are easily syphoned into the fibre tubes." The practical upshot
of this is virtual self-bonding clay. Two pieces will, through capillary action, "weld" together
by drawing particles of the other into itself, forming an almost instant bond that is much
stronger than scoring and wetting. While the shear strength is outstanding the wet join will
be firm but not strong until fully dry.
Fig 1 Normal clay slip at approximately 300X magnification. (Curtin University). Note the
rough but "sealed" surface which restricts penetration of wet clay.
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Fig 2 Paperclay at the same magnification, clearly showing the cellulose fibres impregnated
with clay particles, allowing liquid clay access to the interior of the clay body.1
Paperclay has been in use by ceramicists for approximately 50 years as a means of
producing non-warp, non-crack slabs of clay of any thickness, and for a long time that's
almost all it was ever used for. There is very little history to be found concerning paperclay
as the prime material used in ceramic sculpture and only in the last few years have articles
appeared. There is only one book on the subject to my knowledge 1. In my experience,
paperclay is totally resistant to cracks developing while drying. Joining can be done at any
stage of drying such as wet to wet/ dry/ leather hard. Scoring and wetting are not necessary
as all work can be stuck together using liquid paperclay as "glue". It can be poured onto
plaster blocks to draw most of the water out and then can be rolled, coiled or even wedged
and thrown on a wheel, although some care is needed since basically you are throwing with
slip! In addition, it can be left to dry on a plaster slab to produce sheets without needing to
use a slab roller. A wooden frame and a spreader (similar to a screen printing rubber) that
sits on the top of the frame can produce sheets of precise thicknesses.
Fig 3 One method for producing sheets of paperclay. Adjusting the depth of the cut in the
former alters the thickness of the sheet
Once dry, the sheets of paperclay can be stored on edge indefinitely and used when
necessary. Simply soak them in water for 30 minutes to 2 hours depending upon their
thickness. Dry paperclay exhibits immense strength and surprising lightness as the water in
the paper dries out. When joining a wet or leather hard piece to dry paperclay the moisture
is drawn out very fast and the new piece can be handled within minutes with little chance of
damage. Unused paperclay can be stored wet, dry of even frozen in plastic bags for any
length of time. If leather hard sheets are required for future use simply lay them inside a
large garbage bag. Paperclay can also be attached to other types of smooth clays with
paperclay glue. In a recent experiment, I used paperclay glue to stick a band of
earthenware leather hard paperclay to a dry stoneware bowl. The bowl developed one
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small crack, which I repaired instinctively with paperclay and fired it to 1000C with no
problems. Once pieces are fired they are just as strong, if not stronger, than normal clay
while being lighter. The fired piece is no different to normal clay at this point and can be
surface treated in any way.
Production of Paperclay Slip
The production of paperclay is simple and straightforward. The few artists who have written
about paperclay recommend the use of wheel slops and trimmings, which is fine provided
only one type of clay, is used when throwing. A simple and easy alternative is to use
casting slip when wheel slops are not available or a large quantity of paperclay is required.
The paperclay is produced by adding 30-50% newspaper pulp to the clay slip. The
newspaper should be finely shredded and soaked in hot water overnight, then re-blended
until there is no print readable and partially strained, without compression, before it is
added to the slip. To avoid the resulting smell of rotting paper pulp in the slip, add a
tablespoon of disinfectant when mixing. I use an earthenware slip because it seems less
brittle and more tolerant of thermal shock when I apply an artificial patina to the finished
pieces. The recipe is given in appendix 1.
In its liquid form it can be poured over any surface that is horizontal and somewhat
absorbent. Flat, smooth or textured and patterned surfaces can be used. Graham Hay, who
is currently studying at Curtin and introduced me to paperclay, has used wools and loosefibred twines drawn through a bucket of paperclay, (threading it through a hole drilled in the
centre of a large lead sinker will keep it under), then hung up to dry to produce fine strands
of paperclay that can be cut to any length. He has also investigated several other additions
to the mix in order to achieve different effects, one of which is cooked spaghetti added to
the paperclay, which, after bisque firing, is chipped away to reveal what he calls a "white
ant" body!
Throwing Paperclay
As mentioned earlier it can be thrown on the wheel with some preparation. First pour the
required amount onto a plaster block and let it dry to a little less than leather hard. If it gets
too stiff it will tear and crack when wedged. Once wedged, wrap in plastic and leave for
several days and you will find the soft lump of sticky slip has become a firm piece of clay. It
can now be thrown, however it must be remembered that the paperclay will stress much
quicker than usual due to the paper particles compressing under the pressure of the hand
movements. I usually only get 2 pulls up before it becomes difficult to handle. I also keep
the wall thickness 2 to 3 times thicker than normal.
Moulding Paperclay
Slip casting is a well-known and understood process. Aside from the great production
factory using it, there are as many ways of making slip cast moulds as there are artists
doing it. Having been taught the traditional 2-piece mould with pour hole method, I could
recognise its good and bad qualities. The care taken in producing the master can be
compromised when the casting process is begun. The master is supported on a bed of clay
that is raised to the midway point of the original and carefully mated to it. At this point, great
care must be taken to obtain a smooth seam line without damaging the surface of the
original as well as having a smooth flat surface to the clay supporting bed. Once this has
been achieved a wall of clay is raised around the master and clay bed to 2-3 cm above the
highest point of the master. A plaster mixture is then poured in and allowed to set. Once
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set, the clay bed is removed and the master, now sitting in the plaster, is turned over and
the wall reassembled around it. The plaster is treated with a detergent so that when the
second mix of plaster is poured it can be removed when dry without too much trouble. If
there is not enough detergent or it is forgotten then not only is the mould ruined but also
some damage will be done to the master when it is extracted. This traditional method of slip
casting is a simple but time consuming process, which I always disliked. I searched for an
alternative and it came, surprisingly, from one of the above-mentioned great production
factories. On a tour of its dinnerware production line, I watched a machine produce soup
bowls at the rate of at least 30 a minute. It consisted of four moulds of the inside of the bowl
sitting on a revolving table. A pre-measured disk of porcelain clay was dropped onto each
mould. The table then rotated 1/4 of a turn and a mechanical arm pushed down. In one
movement both the inner and outer shape and foot ring was formed and the rim was
trimmed. I was amazed at how simple it was and realised how I could use the idea in a kind
of reverse way. Instead of forming clay over a mould I would pour plaster over a master but
would not need any clay bed for it to sit on. This is a one-piece mould. Placing the master,
which is usually not clay but some type of found object like a plastic container or sealed
wooden shape, on a sheet of glass coated with a little petroleum jelly so that it will stick to
the glass and not shift when the plaster is poured, the only clay required is for a small wall
to surround the piece. The master must have no under cuts that will prevent future casts
releasing from the mould. The plastic masters are easily removed when the plaster is dry
with the use of a lit match to burn and melt one point so the shape will collapse when
pulled. Don't heat the plaster too much or cracks could develop. The major advantage of
this type of mould is that the poured piece is open to the air and dries faster, which can be
accelerated by the use of a paint stripper heat gun, again taking care not to crack the
mould.
Another drawback of the slip cast mould is the hole required to pour the slip into the mould.
Once the piece is removed from the mould this leaves a hole, which requires cleaning and
filling with a smaller hole left for firing purposes. This is not a great problem except that I
found when arranging one series of fired slip cast pieces that I couldn't use them in one
particular way because of all the ugly holes in the bases. The Cocktail shaker mould was
designed to solve this problem. It consists of two one-piece moulds placed "mouth to
mouth". The first mould is made as described above and allowed to dry. It is then inverted
and a second shape is placed over the mouth of the first. Locating holes are drilled in the
first mould, the detergent coating is applied and a clay wall put in place. The plaster is then
poured and allowed to set. Once dry, the mould is opened and the masters removed. It is
now just a matter of trial and error to work out how much slip, or paperclay, is required to
coat the inside of the mould. The paperclay is poured in, (in tests usually about 1/3 to 1/2 of
the mould volume), the mould is closed and secured and, as the name suggests, shaken
until the paperclay can no longer be heard slopping about in the mould. Note that, if normal
slip is used, an arrangement for the pieces should be decided on before they are bisque
fired. This is not necessary for paperclay pieces since there is no need for the traditional air
hole. One drawback is the time it takes to dry. The mould can be cracked after 2 to 6 hours
and drying can then proceed normally. Note that paperclay takes longer to dry in any slip
casting mould that normal slip due to the paper content.
I've approached the construction of multi piece moulds in the same manner as one-piece
moulds by adjusting the way in which the casting is carried out. Any shape should be
possible simply by adjusting either the master's orientation or the steps in pouring the
plaster. For example,
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an hexagonal piece with recesses cut into the six flat sides could not have a traditional two
piece mould made of it because of the undercuts created by the recesses in the surface of
the master. To solve this, the piece is placed vertically and one side only is walled off with
clay and the plaster poured. The result is a 4-sided wedge of plaster with the detail of the
master on the inner or smallest surface, (fig 4). Leaving the first section in place, the clay
wall is made into an L shape and attached from the outside corner of the plaster to the next
corner of the master with the first section of the mould forming one wall, (fig 5). This wall is
treated with the detergent release agent and the plaster poured. This method could be
carried out six times to complete the mould, which would make it a rather lengthy process.
Instead, the 1st, 3rd and 5th sides are poured, followed by the 2nd, 4th and 6th when they
are dry. One of the sections should have no locating lugs on the surface, as this would
prevent easy assembly and disassembly of the mould. Instead, two parallel surfaces of
each of the two sections of the mould should have open-ended recesses cut into then that
will fill and form lugs when the plaster is poured.
Firing
Firing presents a problem if using an electric kiln. In addition to considering the normal
problems involved with the Quartz inversion (where the chemically bonded water is driven
out of the clay body at 573ºC), the paper itself begins to burn at 300ºC and produces acrid
fumes and smoke, which exit via the bunghole. Safety precautions should therefore be
enacted. All doors and windows should be opened to provide ventilation and time spent
near the kiln kept to a minimum until it reaches 550-600ºC when all the organic material will
have burnt out and the bungs should be closed. Unfortunately this could take a
considerable time as the ramp on firing should be shallow to begin with, no more than 5075ºC per hour up until 300ºC, after which it can be increased to 150ºC per hour up to 600ºC
and then 350ºC per hour up to 1100ºC with a 30 minute soak. If using thin slabs, firing can
be completed extremely rapidly and crash cooled without risk.2 As firing burns out the
paper present, the clay becomes full of microscopic holes that are invisible to the naked
eye which allow the clay to "breathe" during firing. Pieces no longer have to be made
hollow, or with a pour hole to allow expanding air to escape as it uses the holes and spaces
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once occupied by the paper to escape. These holes also act as a ready-made anchor point
for more paperclay glue in case of breakage. The broken piece can be reattached and
refired with no danger.
Various Approaches
Paperclay's forgiving qualities and ease of use lend itself to construction type hand building.
Brian Gartside has taken advantage of paperclay's sheet forming abilities in his nautical
works like "Frigate" and "Pastel in Drydock" producing large free standing boat or ship
shapes out of semi circular sheets and spindly legs of paperclay. Looking much too heavy,
the large superstructure adds tension and excitement to the pieces. Gartside also uses
press and slip moulds to produce various shapes from free standing narrative slabs to
paperclay teacups. Any kind of found object can be pressed into wet paperclay, although
Gartside stresses that only fired or glazed ceramic objects be used if a refiring is planned.
Graham Hay approaches his work and paperclay from a different perspective. He sees
paperclay as a medium that allows him to do mark making in 3 dimensions. (G Hay, per
com August/September, 1994), hence the strings of long thin paperclay floating above
white plaster bases. Hay's work also incorporates, rather appropriately, architectural
elements and structural solutions in dealing with a series of pieces on society's perception
of institutions as the buildings and not the staff and bureaucracy within them. Some, being
tall and spindly, float on 5mm by 30mm legs, 2 to 3 feet above the ground, giving them a
"castles in the sky" feel which amply demonstrates the versatility of paperclay construction.
The advantages of using a slip casting mould, whether using paperclay or normal slip, far
outweigh the time and effort involved in producing the master mould. Once complete the
mould can be used indefinitely as long as care is taken when handled. My own work
consists of paperclay spheres with straps and rivets made out of paperclay. The straps with
rivets attached were cast in a one piece mould, while the rivets were made by casting a flat
sheet of plaster 2.5 cm thick and using a drill press to drill a series of holes to a set depth.
These were then filled with paperclay from a plastic sauce bottle and allowed to dry. The
result is hundreds of rivets that can be glued to any part of the sculpture. Having completed
my own sets of moulds I began a production line set up. I cast and recast pieces that
allowed me to assemble small pieces at the rate of one every two to four hours.
In an effort to supply the reader with as much information on paperclay construction
methods as possible I will describe the work I know best - my own. My approach to
paperclay, as the more astute reader may have noticed, is through the use of slip casting
moulds. By using several moulds I can produce a supply of "parts" for my sculptures and,
as the pieces I produce bear a strong resemblance to machines, I have set up a mini
assembly line to produce them. Using 4 different spheres, several leg and mounting moulds
as well as detail moulds like feet and rivets, a newly cast sphere is matched to a set of legs,
(anywhere from 1 to 6 so far), and basic assembly begun. As I use 2 piece moulds for the
spheres, a hole is cut out of the surface, which takes the pour hole with it. This new larger
hole can then either have a light mounted in it or it can be turned downwards to form the
base of a legless piece depending on how much care was taken when cutting the hole.
Cutting holes in a sphere of green clay may seem a bit daunting but, remembering
paperclay's amazing strength and its cardboard-like consistency when dry, I found that a
circular hole cutter, like the type used by graphic artists, is an invaluable tool. I also use
razor sharp craft knives instead of any old blunt thing that we ceramic artists are likely to
pick up and use. Remember, paperclay is full of fibres, wet or dry, so if you don't want a
rough torn edge use a sharp knife.
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Once the hole or holes are cut, the rough design for the placement of the paperclay straps
and found objects is pencilled onto the surface. The circular band that goes around the hole
in the sphere is cut from a leather hard sheet of paperclay using the hole's diameter as the
inside measurement and then, keeping the same centre point, enlarging the diameter by
1cm and cutting a second hole. The resulting ring of paperclay is glued onto the sphere
around the hole. If the piece has any legs these are attached simply by cutting the top off
the leg and smoothing around the opening so that all that remains is a clean ring of
paperclay that can be mated to the sphere at any angle. Straps of leather paperclay are cut
1cm wide and glued in place according to the pencil marks. Any recesses, holes or
attachment points are made at this point and then the piece is put aside to dry for several
hours. This is done because the dry sphere will draw the water out of the strap rapidly and
a small amount of shrinkage will result where the strap joins the surface. These cracks can
then be filled with thick glue, although this can be messy so I use leather paperclay that is
wedged into a soft putty-like consistency and trowelled into the cracks in the same way. A
drop of water will help smooth the join over. This may have to de done more than once. The
next stage is to apply the rivets to the straps and this is a long slow process as they are
glued on one by one using tweezers. After a final fitting of the found objects and a check for
any marks on the surface or rivets having been knocked off, the piece is ready for bisque
firing. Once the piece is fired a chemical patina is applied to the surface. This requires a
metal base coat to build up on, so I spray a saturated copper slip on to each piece that
consist of 65% copper carbonate or copper oxide, 20% Soda Feldspar and 15% ball Clay.
The pieces are then placed in the kiln and fired to the following program:
75ºC per hour to 300ºC = 4 hours
150ºC per hour to 600ºC = 2 hours
250ºC per hour to 1000ºC = 1 hour 36 min
30 min soak at 1000ºC = 30 min
Total firing time 8 hours 6 min
Once firing has concluded, the kiln is cracked and the pieces can be removed from 2 to 6
hours later. The copper carbonate has turned black and the piece is ready for patination.
First it is heated with a blowtorch. I do this on a banding wheel with a piece of broken kiln
shelf for the work to sit on. The piece is spun slowly and heated with the torch, care being
taken not to play the torch on any area too long or cracks might develop. Although, I might
add that several of the pieces I've done have cracked under the torch with no ill effect:
another advantage of paperclay? And another mystery to solve. As the flame heats the
surface, small flashes of white on the body indicate it is hot enough to apply the chemicals,
these being copper nitrate, ferric chloride and stannous chloride. These give blue/green,
red and a velvety green colour and texture respectively. They are mixed with bakers
soldering solution and applied using a plastic spray bottle. The heat is then reapplied and
this is repeated until certain indicator colours are seen. At this point the treatment is
stopped and the piece put aside. The colour gradually develops over a few days. The
pieces are then finished off by having 240-volt lamps mounted in them.
Conclusion
The real strength of paperclay is its versatility and adaptability. It can be joined to itself at
any stage and retain strength no matter how wet or dry. Half completed work can be left for
months or years uncovered and dry and be added to or broken and repositioned. Paperclay
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in a liquid state is used for the glue and even it can be adapted to suit requirements: thick as a straightforward bond former, or extremely thin where delicate work is in progress, as it
will seep into the space between the pieces and form a strong bond with no smearing to
mar the work. Liquid paperclay can be poured and cut to shape and then left to dry before
work begins. Finishing the piece is then as easy as gluing cardboard together, with the
added advantage of it being in three dimensions. By casting and storing sheets of green
clay, once work begins on a piece it can be completed in a matter of hours without the
pressures of keeping certain areas moist while having to work around external supports.
Also, because up to 50% of the clay is substituted with paper, in its pre-fired state it is light
but strong and some pieces may not even need bisque firing. "After bisque firing the
appearance and texture are normal in every way. The fired clay looks and acts as clay
always does. The minute spaces formerly occupied by the cellulose fibres cannot be seen
by the naked eye and the only noticeable difference will be a lightness in
weight..."(Gartside, 1994)
Rosette Gault's book is eagerly awaited by both Graham Hay and myself, as the subtitle "A
Studio Companion" promises not only more views of her work but perhaps some new
methods of working with paperclay. Paperclay's ability to produce perfect sheets of clay has
blinded many ceramic artists to the other possibilities it presents us with. Many new works
are being produced with paperclay but I've see few that are anything but sheets cut,
stacked, layered, glued, rolled, bent or positioned in some other manner to produce a piece
of work. While I see no problem with that approach and there are some stunning works out
there, I feel that full exploitation of paperclay's advantages is being neglected. As far as I
am aware, I am the only person working with slip casting moulds and paperclay and use
very few flat sheets or surfaces. Using slip-casting moulds with paperclay has eliminated
many problems while creating a few others.
The versatility of paperclay cannot be overstated. We have at our disposal a medium that is
simple to make and even simpler to use. No skill at all is needed except for imagination. If
you can glue two pieces of paper together then you can create art. I believe that paperclay,
once it is more widely known, is going to change the face of contemporary ceramics, as we
know it.
Appendix 1: Slip Recipe
The slip is prepared to the following recipe developed by Jenny Sullivan, the former
ceramics technician at Edith Cowan for slip casting.
FX Ball Clay 6 kgs BBR Caolin 5 kgs Silica (300 mesh) 6 kgs Fine Cullet (Glass) 3 kgs
Water 10 Lts Sodium Silicate 70 gms Dispex (Liquid) 70 gms These amounts can be
doubled or halved to get the required amount of slip.
SAFETY NOTE: Silica is TOXIC and a mask should be worn when preparing slip.
Once the slip is prepared, it is sieved through a 60-mesh screen into the mixing bucket. The
pulp is then added and mixed thoroughly. The still wet fibres draw slip in immediately and
thus the mixture can be used straight away, however it should be left to stand for 30
minutes to ensure total saturation of the fibres.
Appendix 2: Test Results
This series of tests was conducted to answer four questions:
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What is the optimum mix of paper pulp to add to the earthenware slip (from appendix 1)?
What are the shrinkage rates of the different mixes of paperclay, both leather hard and
Bisque?
Can fired paperclay be reglued and refired?
Can solid shapes be fired? (In this case a 60mm ball fired to 1000ºC at 200ºC per hour to
see if it could also survive such a rapid rate of temperature rise.)
Shrinkage Test
Paperclay
Pulp Mix
10%
15%
20%
25%
30%
Poured Size
(mm)
100 x 50 x 10
100 x 50 x 10
100 x 50 x 10
100 x 50 x 10
100 x 50 x 10
Leather hard
Size (mm)
98 x 48 x 7
98 x 48 x 9
98 x 48 x 8.5
98 x 48 x 9
98 x 48 x 8.5
35%
100 x 50 x 10 98 x 48 x 9
40%
45%
50%
100 x 50 x 10 99 x 49 x 8.5
100 x 50 x 10 98.5 x 49 x 8
100 x 50 x 10 98 x 49 x 8
Dried Size
(mm)
96 x 47 x 8
93 x 46 x 9
94 x 47 x 8
92 x 47 x 8
94 x 43 x 8
92 x 46 x
7.5
94 x 47 x 6
93 x 45 x 7
92 x 47 x 8
Bisque Size
(mm)
92 x 45 x 6
90 x 45 x 8
90 x 46 x 7
92 x 45 x 7
90 x 45 x 7
Length %
Shrinkage
8
10
10
8
10
90 x 46 x 7
10
92 x 46 x 6 8
93 x 45 x 6 7
91 x 45 x 7.5 9
Refiring Test
Two pieces of each paper pulp mix were fired then broken. One was reglued using glue of
the same consistency as the original mix. The other was reglued using 30% paper pulp
glue. All pieces failed to rebond after refiring. This test is not conclusive since the reglueing
technique may have been at fault.
Solid Ball Test
A 60 mm diameter solid ball of wet paperclay of each % mix was fired at 150ºC/hr to 300ºC,
then 250ºC/hr to 600ºC, then 350ºC/hr to 1000ºC. Also in the firing was a control ball made
of wet slip containing no paper pulp. The control ball exploded in the kiln, balls with 10, 15,
20 and 25% paper pulp had a large flake break off during firing, interestingly the flake came
off where the percentage number was scored into the surface. This leads me to believe the
scoring created a funnel, which allowed the steam to escape a greater velocity and thus
damage the ball. The remaining balls showed no sign of damage.
Footnotes
1. "Paperclay for Ceramic Sculptors, A Studio Companion" Rosette Gault, Published 1994
2. If firing thin slabs or delicate work, the bisque firing can be programmed at 250ºC/hr to
200º then 350ºC/hr to 1100ºC with a 30-minute soak. Switch off kiln and crack the door.
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Bibliography
Caplan, Jerry. (1994). Paper/Clay Again. New Zealand Potter, 36 (1), 18.
Gartside, Brian. (1993). ...Mix What with Clay? New Zealand Potter, 35 (1), 32.
Gartside, Brian. (1994). Suitcase Art. New Zealand Potter, 36, (1), 17.
Hay, Graham. (1994). Paperclay, (Handout for paperclay workshop at Edith Cowan
University)
Hay, Graham (1994) personal communication, March to September 1994
Rassell, Jennie. (1993). Paper Clay, Rosette Galt at NCECA, San Diego 1993. New
Zealand Potter, 35 (2), 20.
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