Ashanti Casting Technique

Ashanti Casting Technique
The Ashanti casting technique was developed by the Akan Ashanti people who live in
Ghana. This technique is a lost wax casting method known as fonte à cire perdue or lost
wax casting.
The lost wax method has been used for around 6,000 years and is still used in various
ways today to cast metal for industrial, craft and art applications. It is mainly used for
copper, silver and gold alloys.
The procedure is always the same: First the object that is to be made out of metal is
shaped in wax. The wax used is beeswax, today also with industrially manufactured wax
sheets, wire, profiles or blocks that can be drilled, milled and ground. When the wax
model has been shaped, casting and normally also additional venting channels are
provided. The finished model is then covered with a shell of a fireproof moulding
compound. Only the ends of the channels protrude from one side of the mould. When
the casting mould has dried, it is heated upside down so that the wax can flow from the
channels. Molten metal that has been heated in a separate crucible is then poured into
the resulting hollow mould, the negative mould of the wax model. As soon as the metal
has solidified, the mould is broken and the object previously created from wax is then
recreated as a unique metal piece.
The wax model can only be used once and must be re-made for each new cast, as the
shape is lost when the wax is melted. If the cast is unsuccessful, a new wax model must
be created.
The special feature of the Ashanti casting technique is that the casting mould described
above and the melting crucible are inseparably connected. As a result the metal is
melted without exposure to the oxidising ambient air and cast in an enclosed system by
turning the mould. With this clever method, thin-walled objects can be made with great
attention to detail without the use of complicated apparatus. The model is made of
beeswax, the casting mould and the crucible of clay with varying amounts of charcoal
and horse manure.
The following pages contain a series of images and a description of how a bangle is
crafted with the Ashanti casting technique.
Technical description
The fireproof clay cores are shaped,
dried and fired.
The fired core is shaped by filing
and sanding.
The core is finished. This
superficially covered in wax.
is
Finished wax model of the bangle.
The core of fireproof clay is covered
in wax. The wave pattern is already
cut out around the bangle.
The casting
channels made
of wax wire are
fitted. The
mould is ready
for the first
coating of clay
and charcoal slip.
The first shaping
coating is painted
on with a brush and
hangs in the shade
of a tree to dry.
The mould is
covered with the
third and last
layer of the clay
and charcoal slip
and dried.
It is then covered
carefully in stages
with a supporting
shell made of a
mixture of fireproof
clay, fireclay and
horse manure. The
mould is dried after
every stage.
The clay mixture is applied
without moistening the
underlying layer too much, as
the mould is brittle when it has
not been fired.
The wax model is covered and
ready for melting the wax. The
funnel-shaped upper section of
the melting crucible is mounted
on the side of the converging
casting channels.
The casting moulds are slowly heated in
the charcoal embers with the crucible
side facing downwards until the wax
starts to run out and burns, producing
smoke.
The model, the wax, is then "lost" and a
hollow mould is then ready for the
molten metal.
The melted casting mould is covered
and reinforced with a second layer
of clay.
The casting opening is closed with a
thin wax tablet to prevent any
contaminants entering the hollow
mould.
The metal is then weighed in pieces in
accordance with the wax weight and
filled into the crucible.
Suitable crucible covers are ready to
close the mould.
The casting mould is ready
for the last layer of fireproof clay.
Finished casting moulds.
The melting furnace heated with
charcoal is ready for use. The
combustion air is supplied with
bellows on the underside of the
furnace. The casting moulds are
placed upside down into the
furnace and covered with charcoal.
The furnace is fired until the embers
have reached the top. It is
alternately stirred and stoked until
the metal has melted.
The glowing casting mould is
pushed out of the furnace and
then turned so that the molten
metal flows into the hollow
mould.
The mould is cooled very slowly
overnight in the ashes.
After cooling the most
exciting moment has arrived the clay shell is broken open,
first carefully on the crucible
side to check whether the
metal has run completely into
the shell.
The mould side is then split
with a clean knock. The casting
process was successful. The
model is also completely filled
with the gold alloy!
The casting channels are
then separated and the
dark oxide layer is
removed with citric acid
and alum.
Bibliography
Max Fröhlich: Gelbgiesser im Kameruner Grasland, 1979 Museum Rietberg, Zurich
E. Fischer / H. Himmelheber / M. Fröhlich: Das Gold in der Kunst Westafrikas / Zur Technik des
Goldgusses bei den Ashanti, 1981 Museum Rietberg, Zurich
Max Fröhlich: Cire-Perdue-Guss / Lost-wax casting, 1995 Zürich
Johanna Dahm: Lost and Found, 1999 Verlag Niggli, ISBN: 3-7212-0355-0
Johanna Dahm: same same, but different, 2008 Verlag Niggli, ISBN 978-3-7212-0684-5
Das Gold der Akan, Museum Liaunig, 2008 HL Museumsverwaltung GmbH,
ISBN 978-3-9502610-1-1
Georg Eisner: Wunderwerke westafrikanischer Goldgiesserkunst, 2012 CH-Bollingen
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