That most elusive of patinas comes to the forefront— complete with

all levels
reference
That most elusive of patinas comes to the forefront—
complete with some concrete advice on how
to capture it in all its glory.
by Linda Kaye-Moses
fascination with objects of antiquity has led artists—and art jewelers in
particular—to create finishes on their work that approximate the patinas
wrought naturally by aging. For artists working in metal, patination can be
artificially accomplished through the use of chemicals, heat, and sometimes paint.
Patination produces a twofold result: An array of color emerges, and the textural
treatment on the surface of the metal is intensified because of the contrast between
patinated and nonpatinated areas.
This article focuses on liver of sulfur—also known as potassium sulfide or
sulfurated potash—as a patination agent for sterling silver, fine or pure silver (in the
forms of rolled sheet and metal clay), and copper. Liver of sulfur has almost no effect
on brass or nickel silver, and gold is usually left unpatinated.
Patinating metal with liver of sulfur is merely a starting point to the wonderful
world of patinas. With a little time and experimentation, you will discover the best
way to achieve the patina you prefer on your jewelry—one that will personalize your
work and make it unique.
A
© 2015 Kalmbach Publishing Co. This material may not be reproduced in any form
Art Jewelry • January 2005
49
without permission from the
publisher. www.ArtJewelryMag.com
tips
to remember
When working with liver of
sulfur as a patina agent, keep in
mind the following pointers:
Metal objects to be patinated
should be highly polished before
application of the liver of sulfur.
A bright, reflective surface on
the metal will produce a more
striking patina.
■
After polishing, the surface of
the metal object must be
thoroughly cleaned and
degreased. Brush vigorously
with a soft bristle brush (such as
a toothbrush), hot water, and
liquid dishwashing detergent.
Then rinse and dry fully. Residue
on the object can affect the
patina, preventing it from
making contact with the metal.
■
Adding a heated metal object
to a liver of sulfur solution that
is also hot will produce a quick
and intense patina.
■
Brushing with soapy water
and a brass jeweler’s brush
after each rinsing during the dipand-rinse patination process will
produce a shiny and uniformly
dark patina.
■
The Lowdown on
Liver of Sulfur
After your object is patinated,
you may coat it with lacquer,
microcrystalline wax, or
beeswax. These materials
will help protect your
patina, but they often
subtly change the
color of your
patina and
need to be
removed and
reapplied every
few years.
■
You may find that
the patinas you apply
are long-lasting and never
need a protective coating.
■
50
Art Jewelry • January 2005
note
Liver of sulfur is a relatively safe
caution
chemical; of the patina
chemicals, it’s the most
As with all chemicals, exercise
harmless. However, since liver
caution when preparing and using
liver of sulfur. Keep your
of sulfur generates fumes,
workshop equipment and tools
make sure you are working in
separate from your kitchen
an area that is actively
facilities—and whatever you do,
don’t share containers and
ventilated. You must remove
utensils from one space to the
the fumes from the air around
next! Your liver and onions
you by positioning a fan that
shouldn’t have an
aftertaste of liver
will not draw the fumes past your
of sulfur.
nose, but will, instead, vent the
fumes away from you and to the
outside. This can be as simple as working at
a bench or table placed directly in front of a
window in which there is a fan actively pulling air to the outside. Be
responsible when using chemicals: Take care of yourself.
A solution of liver of sulfur produces a disagreeable smell similar to rotten
eggs. In fact, eggs give off sulfur fumes—and can produce a patina on metals!
(See “The Incredible Egg: It’s Not Just Edible,” opposite below left.) Wear rubber,
latex, or nitrile gloves when working with liver of sulfur, otherwise the smell of
the chemical will cling to your hands. Or use tweezers that aren’t reactive to
metals (such as bamboo, plastic, or stainless steel) instead of wearing gloves.
The liver of sulfur used in jewelrymaking comes packaged in two forms:
rocklike pieces and liquid solution. The latter is ready to use but expensive, and
if it’s not used quickly it deteriorates, which makes it impractical for many
artists. The rocklike version comes packaged in an airtight, opaque container;
the chunks range in size from pebbles to gravel to rocks. Although it requires a
little more preparatory work, it’s the most stable form and is discussed here.
Unpatinated metals, left to right:
sterling silver, copper, fine silver,
and silver clay.
Liver of Sulfur: Cooking 101
Process photos by Evan Soldinger.
To prepare the liver of sulfur for use, it first needs to be broken into small
pieces, above right. Wearing gloves or using tweezers, remove a piece from its
container and place it inside one heavy-duty plastic (freezer-type) bag nestled
inside another bag. Place the bags on an anvil or a bench block and use a
mallet or hammer to reduce the size of the chunk to pieces no larger than very
small peas. Since light and moisture cause liver of sulfur to deteriorate, slip
these pieces into a small, opaque, sealable container for storage until you are
ready to use them for patination. A black film canister works nicely.
When you are ready to use the liver of sulfur, dissolve a small piece in hot
tap water in a stainless-steel bowl or glass measuring cup (both are nonreactive).
Don’t use boiling water, which releases toxic fumes. The color of the solution
should be lighter in color than an egg yolk—kind of a yellow with a green
undertone, center right. A darker or more intense solution will produce a patina
faster, but the resulting sulfide layer is often fragile and may flake off. Use the
solution as soon as possible; the longer you wait, the less effective it becomes.
Warm premade solution for each use by putting it in a heatproof container
inside a pan of water on top of a stove (think heating up a baby bottle). If you
have a microwave dedicated to workshop use, just heat it in there.
You can store newly made solution in airtight and lightproof containers
such as opaque or dark brown medicine bottles. As long as the solution retains
a yellow color, it is still viable. If it has turned clear, with little flakes in the
bottom of the bottle, the solution has deteriorated beyond use. Fully
deteriorated liver of sulfur may be disposed of safely, but check with your
municipal sewer department for specific information.
The quantities of liver of sulfur used for a solution vary slightly depending
on the metal to which it will be applied. Check out "Patina Soup," page 52, for
specific details and techniques for the metal you wish to patinate.
further
reading
the
incredible egg
it’s not just edible
A tried-and-true, low-tech way to achieve a patina on silver
and copper is to use a hardboiled egg. While this process
isn’t as fast or controllable as using liver of sulfur, the
results can be most interesting. Because older eggs give off
more sulfur, use past-their-date eggs for best results.
1. Place your metal object and a peeled hard-boiled egg in a
jar and cover tightly.
2. Set in a warm environment, checking the intensity of the
patina from time to time. This may take up to several days.
Optionally, you can set the jar in the fridge to slow the egg’s
deterioration, but this will take longer to develop a patina.
3. When the color you want has been achieved, remove the
object and complete your patina as you would have done if
you had used liver of sulfur.
Here are two books to get you
started on metal patinas:
The Colouring, Bronzing and
Patination of Metals, by Richard
Hughes and Michael Rowe ($85;
Watson-Guptill Publications,
2004; ISBN: 0-8230-0762-6).
A book for the advanced
metalworker or those trying to
capture a specific patina.
■
■ Creative Metal Clay Jewelry,
by CeCe Wire ($27.95; Lark Books,
2003; ISBN: 1-57990-301-0).
Focusing primarily on projects
using metal clay, this book also
features some terrific tips on
how to achieve colored patinas
on the fired results.
PATINA SOUP
Presented on these two pages are four recipes for achieving liver of sulfur patinas,
including a dark patina on sterling and fine silver, a dark patina on copper, a dark patina
on metal clay, and a colored patina on sterling and fine silver and copper. Pieces to be
patinated are most often fully immersed in the solution, which is the method discussed
here. If you desire, you can brush the solution on specific areas of your pieces, using an
artist’s brush.
To Create a Dark Liver of
Sulfur Patina on Copper
On copper, use a weak solution and scrub
with a brass jeweler’s brush between each
dip to create a purplish gray. It’s especially
important that you remove all fingerprints
before darkening copper, otherwise the
patina pattern will be uneven.
1. Make up a hot liver of sulfur solution—
about 1 cup of hot tap water and a
To Create a Dark Liver of Sulfur Patina on
smaller than pea-size piece of liver of
Sterling Silver and Fine Silver
sulfur. The solution should be a clear
1. Make up a hot liver of sulfur solution—about 1 cup of hot tap water and a
light yellow.
pea-size piece of liver of sulfur.
2. Rinse your metal object in hot water so
2. Rinse your metal object in hot water, which will heat it so it accepts the
it accepts the patina better.
patina better.
3. Drop the object in the hot liver of sulfur
3. Drop the object in the hot liver of sulfur solution and remove it after several
solution and remove it almost
seconds with gloved hands. You may also use nonreactive tweezers, being
immediately with gloved hands. (You
careful not to scratch your object or to splash solution on your hands.
may also use nonreactive tweezers,
4. Rinse in hot running water, then reimmerse the object in the solution for
being careful not to scratch your object
another few seconds. Repeat the cycle until the patina is as dark as you wish.
or to splash solution on your hands.)
Though this method takes longer than simply letting the
Copper will darken much more quickly
piece soak in solution, following it lets you darken
than silver, so move with speed.
the metal gradually, giving you some control
4. Rinse in hot running water, then
over the patination process.
reimmerse the object in the solution for
5. Give a final rinse in hot water mixed with a
another second or two. Repeat if
on masking a patina
little dishwashing liquid; remove your
necessary until the patina is as dark
protective gloves.
as you wish. Copper darkens so
You may want to produce a
6. Use one of the two finish methods,
rapidly that it’s difficult to control,
piece that has both patinated and
unpatinated areas. To prevent
opposite, for completing the patina.
but this procedure prevents an
certain portions from darkening,
abrupt darkening of the metal.
mask them by lightly painting
5. Give a final rinse in hot
rubber cement on them. Allow the
rubber cement to dry and then
water mixed with a little
proceed with the appropriate
dishwashing liquid; remove your
patination process. After
protective gloves.
patinating and rinsing, peel
away the rubber cement
6. Use one of the two finish
and finish.
methods, opposite, for completing
the patina.
note
52
Art Jewelry • January 2005
To Create a Dark Liver of Sulfur Patina
on Fine Silver from Metal Clay
Fine silver that is produced using metal clay
requires a slightly different process, including a
burnishing step. If the surface isn’t burnished, it
can retain some of the liver of sulfur solution and
will therefore continue to darken (an attribute
that may actually be worked into a design).
1. Burnish by hand using a steel jeweler’s
burnisher or brushing vigorously with a brass
or steel jeweler’s brush and a few drops of liquid dishwashing detergent. If you have an
electric tumbler, you may also burnish your piece using steel shot, water, and a few
drops of liquid dishwashing detergent; tumble for a minimum of a half hour to a
maximum of an hour. Wash your piece after it is burnished.
2. Make up a hot liver of sulfur solution—about 1 cup of hot tap water and a much smaller
than pea-size piece of liver of sulfur. The solution should be a clear, very light yellow.
3. Rinse your metal object in hot water, which will heat it so it accepts the patina better.
4. Drop the object in the hot liver of sulfur solution and remove it after several seconds
with gloved hands or nonreactive tweezers, being careful not to scratch your object or
to splash solution on your hands.
5. Rinse in hot running water, then reimmerse the object in the solution for another few
seconds. Repeat this immersion/rinsing procedure until the patina is as dark as you
wish. This prevents an abrupt darkening of the metal and provides some control over
the patination process.
6. Give a final rinse in hot water mixed with a little dishwashing liquid. You may remove
the protective gloves now.
7. Use one of the two finish methods, right, for completing the patina.
To Create a Colored Liver of Sulfur Patina on
Sterling Silver, Fine Silver, Copper, or Metal Clay
You may have noticed that, when creating a dark patina, the patina goes through a
range of colors as it darkens—approximately gold to brown, rose to violet, then to blue
and black. Although patination is an inexact process, by controlling some aspects of it
you can create a metal object that glows with one or more of these colors.
1. Make up a cup of hot liver of sulfur solution. Use a pea-size piece of liver of sulfur
for sterling and fine silver, and a smaller piece for copper and metal-clay fine silver.
To produce a more vibrant rose or violet coloration, add a drop of household
ammonia to the liver of sulfur solution; add a bit more to enhance the blues. To
produce deeper brown tones, add a little baking soda to the solution.
2. Rinse your metal object in hot water so it accepts the patina better.
3. Drop the object in the hot liver of sulfur solution and remove it after several seconds
with gloved hands or use nonreactive tweezers.
4. Immediately rinse in cold running water, checking the color of the patina. Cold
rinsing will slow the patination process, giving you time to control the color. Repeat
this immersion in the hot solution and the quick cold-water rinsing until the patina
displays the colors you wish.
5. Give a final rinse in hot water mixed with a little dishwashing liquid.
6. Use one of the two finish methods, above right, for completing the patina.
Finish Methods
Make sure your piece is properly
clean by washing it one last time in
hot water mixed with dishwashing
liquid. You may also rinse with a few
drops of soapy household ammonia
in hot water, as this helps to
neutralize the liver of sulfur. Then
decide which level of patina you
would like on the piece.
High-Low Patina: To highlight and
emphasize a textured surface, use a
clean, 100% cotton cloth (old white
dress gloves are great for this
purpose). Wrap your index finger in
the cloth and dip it in oil (either oil
of wintergreen or a light kitchen oil)
and then a little fine-grade pumice
(from jeweler and woodworker
suppliers). Gently wipe the mixture
across the surface of your object,
removing the patina from the high
spots and leaving the patina in the
recesses. Wipe the surface with a
clean section of the cloth. Rinse your
piece in hot water and dishwashing
liquid to remove the oil and dry.
Overall Patina: To achieve an even,
all-over patina, add a drop of liquid
dishwashing detergent to the bristles
of a brass jeweler’s brush and
vigorously brush the surface of your
object, getting into the crevices.
Rinse and dry. Z
technique
metal
BEYOND PATINAS
Techniques
examples of how you can
use seven different media to enhance etched,
patinated copper.
See
To color the copper
portion of Ritual Shield
pendant, Pat Gullett first
patinated the copper,
then brushed thinned
green acrylic paint into
the recessed areas.
Once the paint was
dry, she used black
Prismacolor colored
pencil to highlight the
design and added
several coats of a clear
spray lacquer to seal
the pendant.
by Pat Gullett
P
atinas are chemical solutions that color metals,
Start by applying a chemical patina solution, which
such as copper, mimicking the natural colora-
acts like a base coat that allows other media to stick to
tion (also called a patina) caused by weathering
your metal. Then apply one or more media over the
and time. But what if you want to explore beyond the
patina base coat. For durability, protect your colors with
commercially standard patinas like the blue-green of
a clear sealant. The chart on pages 32 and 33 shows what
verdigris or liver of sulfur’s characteristic black? Instead of
combinations of seven media and three topcoats look
mixing chemicals and hoping you get the right color, dip
like over a green-verdigris-patina base coat. Use this
into your art supplies to create more predictable results.
chart as a starting point for your own experiments.
© 2015 Kalmbach Publishing Co. This material may not be reproduced in any form
without permission from the publisher. www.ArtJewelryMag.com
materials
Copper sheet (etched or textured
sheets show most depth of color)
■■ Commercial chemical patina
for copper
■■ Coloring media (choose one or more):
■■ Oil paints, paint thinner
■■ Acrylic paints
■■ Mica pigment powders
■■ Gold leaf, size (adhesive)
■■ Alcohol inks, alcohol-ink thinner
■■ Metallic wax finish, tissue
■■ Prismacolor colored pencils,
colorless blender pencil
■■ Clear protective topcoat, such as:
■■ High-gloss spray lacquer
■■ Microcrystalline Renaissance wax
■■ Matte acrylic spray
■■
tools & supplies
Scouring pad, sandpaper, or
sandblaster
■■ Rubbing alcohol
■■ Electric warming tray; or heat gun
and heat-proof surface
■■ Protective gloves: rubber or nitrile
■■ Paintbrushes
■■ Respirator
■■
See Suppliers, page 77
See Safety Basics, page 73
Prep your piece for patination
Before you patinate a piece of jewelry,
finish piercing, texturing, forming, and
soldering it; subjecting it to tools and
heat will likely harm the patina. Also,
keep in mind that patinas are somewhat
unpredictable, so a given technique will
have varying results each time you use it.
Prepare the surface of the metal. To
create a “tooth” that will grip the patina
base coat, use a scouring pad, sandpaper,
or a sandblaster to abrade the surface of
the metal. Doing this will also expose a
clean surface of metal to which the patina
can adhere. (Do not use greasy abrasives,
such as buffing compounds.)
as a Pyrex container) and warm the
metal with a heat gun. The heat will
speed up the chemical reaction when
you apply the patina.
Apply the patina base coat. Paint a thin
layer of patina over the warmed metal, and
allow it to air-dry. You can apply additional
layers to deepen the patina’s color. Allow
the patina to dry between applications.
Humidity and temperature levels
will affect the outcome of your patina.
To speed up the reaction time, use the
warming tray or heat gun. Allow the
metal to dry thoroughly — several hours
or overnight — before you experiment
with applying other media.
Clean the metal. In order for the patina
to coat your metal evenly, your metal must
be free of any dirt or oils. Rub the metal
with a lint-free cloth soaked in rubbing
alcohol to ensure a clean surface.
Warm the metal. Place
your metal piece on an
electric warming tray
(for warming food on a
buffet) to evenly heat
it. Or, you can place
your metal on a heatproof surface (such
etched
texture
Patinas and colors show up best on textured metals.
Etched metal sheets provide a great texture when you’re
experimenting with patinas, and they’re easy to make.
Check out “D Battery + Saltwater = Cheap, Acid-Free
Etching,” page 62, to learn about a cool etching technique you can use to create your own textures.
construction
of a riveted pendant
To make a piece of jewelry like Ritual
Shield pendant, begin with an etched
sheet of copper. Hydraulically form the
sheet into a dome, then saw it to shape.
Saw out a slightly larger sterling silver
backplate, texturize it, and solder a finding to the back (you could make a bail or
hooks, as shown on the pendant, or you
could use a brooch pin back, as in the
illustration). Then drill and rivet the copper
dome to the sterling backplate, using
brass balled-up wire rivets. For information on sawing, soldering, and riveting,
see Basics, page 71, or visit www.
artjewelrymag.com/howto.
www.A r t J e w e l r y M a g . c o m 31
1 Metal, 1 Patina,
Topcoats*
High-gloss spray lacquer
Microcrystalline wax
Matte acrylic spray
Patina alone
Product: Sophisticated
Finishes’ patina in green
verdigris color
Technique: Painted three
coats, allowing patina to
dry between coats
Patina + Oil paint
Coloring Media
Product: Light blue oil paint
Technique: Light coat
brushed into recesses
Note: Makes its
own sealed
Long
barrier on
drying
the metal
time
Patina + Acrylic paint
Product: Acrylic paint in
green, teal, blue
Technique: Paint thinned with
water, then mixed on metal
and dabbed into recesses
Note: Slight reaction with
patina while drying created
some lightened spots
Best
range of
colors
Patina + Colored mica
pigment powder
Product: Perfect Pearls in
magenta, purple
Technique: Each color mixed
with water to form paste,
then painted on metal
Most
sparkle
Patina + Gold leaf
Product: Imitation, variegated
gold leaf (22k gold would
also work)
Technique: Thin layer of metal
leaf “size” (adhesive) painted
on metal and allowed to
dry; once size was tacky,
leaf was applied and buffed
with soft brush
32
Ar t Jewelr y
■
November 20 0 8
Intensified
colors
Wax
application
removed
some leaf
24 Results
Topcoats*
High-gloss spray lacquer
Microcrystalline wax
Matte acrylic spray
Patina + Alcohol ink
Coloring Media
Product: Adirondak Ink in
three shades of brown
Technique: Ink applied, then
drops of alcohol-ink thinner
provided contrast
Note: Color faded after light
sanding, so additional ink
was applied
Greatest
depth of
color
Patina + Metallic wax finish
Product: Amaco Rub ‘n Buff
in coppery red
Technique: Used finger to
rub light coat onto raised
surfaces, then lightly buffed
with tissue for shine
Note: Waxy finish seals metal
Reduced
metallic
finish
Patina + Colored pencil
Product: Prismacolor
colored pencils
Technique: Multiple layers
built up in recesses and
blended with colorless
blender pencil
Note: Waxy finish can be
buffed to a light shine with
a soft cloth
Muted
colors
* Notes on the topcoats
Clear sprays:
Seven thin layers were sprayed
an hour apart to produce a
protective coating and create
desirable depth of color.
Microcrystalline wax:
One to two thin layers of microcrystalline wax were rubbed onto
the surface with a lint-free cloth
to protect the color and metal.
Notes on the experiment
• All samples of copper sheet were etched to the same depth.
• Each color medium was applied uniformly across each copper sheet.
• For greater contrast and to test durability, all copper samples were lightly
sanded (800–1500 grit) after color medium was dry and before any clear
topcoats were applied.
• Use caution, and spray any topcoats outside. If sprayed inside, ensure
adequate ventilation and wear a respirator.­­ www.A r t J e w e l r y M a g . c o m 33
TECHNIQUE
ALL LEVELS | PATINA
Experiment with a
Traditional Japanese
Trade in your default patina for one you make yourself
using easy-to-acquire household materials.
by Kazuhiko Ichikawa
© 2015 Kalmbach Publishing Co. This material may not be reproduced in any form
without permission from the publisher. www.ArtJewelryMag.com
cover story
materials
Fine or sterling silver piece,
fully fabricated and polished
■■ Vinegar, 100 cc (approx. 61/2 Tbsp.)
■■ Table salt, 6 g (approx. 11/4 tsp.)
■■ Copper sulfate, 6 g (approx 11/4 tsp.)
■■
tools & supplies
G
Torch with soldering/annealing setup
Pickle pot and pickle
■■ Glass container
■■ Nonmetal stirrer
■■ Toothbrush
■■ Baking soda
■■ Latex or nitrile gloves
■■ Container for hot water (optional)
■■ Abrasive papers (optional)
■■ Paste wax (optional)
in-hurubi is one of the easiest and safest traditional Japanese patinas
■■
■■
to use. Translated to English, gin means “silver” and hurubi (or furubi)
means “antique color.” With results ranging from light brown to dark
purple depending on the proportion of the ingredients, this patina works
best on fine silver. Although in Japan, ordinary liver of sulfur patina is also
commonly referred to as gin-hurubi, the recipe I share is for the traditional
gin-hurubi patina.
Before you begin. Complete all fabrication processes, including polishing, before
you apply the patina [1]. Solder doesn’t
readily accept the patina, so carefully
remove any excess solder.
NOTE: Gin hurubi is a patina for silver,
so most alloys containing silver (such as
sterling silver, shibuichi, and Argentium
sterling silver) will darken . The color
may vary on alloys due to uneven metal
composition, so to ensure an even result,
I use fine silver or create a layer of fine
silver on sterling silver.
Prepare the silver. (If you use fine silver,
you can skip this step.) Use a torch with a
soft, bushy flame to heat the sterling silver
[2]. The copper on the surface will oxidize
and turn dark. Quench your piece in water,
and place it in pickle to clean it. Rinse and
dry your piece.
1
Repeat this process 5–6 times, or until
the surface of the sterling silver doesn’t
darken anymore when heated. After you
remove your piece from the pickle the
final time, it will appear matte white.
NOTE: This process, commonly known
as “depletion gilding,” eliminates copper
from the surface of sterling silver, leaving
behind a thin layer of fine silver.
Clean the silver. Use a toothbrush with
a baking-soda-and-water paste to clean
and polish your piece [3]. This method is
gentle enough to clean the silver without
removing the fine-silver layer. Don’t use a
polishing motor to buff your piece: this is
too aggressive. Rinse the piece thoroughly.
NOTE: This process also degreases the
metal, an essential step when preparing
metal for any type of patina .
Find out where to buy supplies, page 79
See Safety Basics, page 75
BASICS & VIDEOS
Learn fundamental techniques
in these bonus tutorials:
•
Pickle Basics
•
Basics, page 73
Videos, www.artjewelrymag.com/videos
ONLINE EXTRAS
Compare liver of sulfur and
gin hurubi on fine silver, and see samples of gin hurubi on other silver alloys.
•
Learn how to prep your
metal before applying a patina.
• Sealants: When and How to Use them
www.artjewelrymag.com/reference
•
2
3
www.ArtJewelryMag.com
57
Mix the patina. Put on a pair of latex
or nitrile gloves, and pour 100 cc (approx.
61/2 Tbsp.) of white vinegar (I use Crops, one
of the cheapest vinegars in Japan) into a
small glass container. Carefully add 6 g
(approx. 11/4 tsp.) of salt and 6 g (approx.
11/4 tsp.) of copper sulfate to the vinegar.
patina
disposal
Although it’s very pretty, the gin-hurubi
solution contains copper ions (copper
atoms missing two electrons [Cu2+]), which
are an environmental toxin known
to poison fish and cause major problems
when it comes in contact with natural
waterways. Before discarding your spent
solution, check with your local government for regulations regarding the proper
disposal of copper ions.
One way to remove the copper ions is to
add aluminum foil to the solution. When
it is added to the salt, vinegar (acetic acid),
and copper sulfate, electrons can move
from the aluminum atoms to the copper
atoms. When this happens, the aluminum
is oxidized, dissolves into the acid, and
forms aluminum sulfate. The copper, having accepted two electrons, will form a
solid and sink to the bottom of the container. It can then be dried and recycled.
The reaction is exothermic, so be sure that
you don’t touch the container, as it can get
hot, and always work in a well-ventilated
space. Make sure that all of the copper has
been removed, so if your solution has a
bluish color, add more aluminum foil.
What about the resulting aluminum
sulfate? It’s is often used in the treatment
of waste water and will be removed by
waste-water treatment plants. — Dr. Chris
Babayco, Assistant Professor of Chemistry, Columbia College, Columbia, Mo.
58
Art Jewelry
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January 2014
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NOTE: Copper sulfate is used as a fungicide, root killer, algaecide, and herbicide.
The hydrated version (the most commonly
available, known as copper sulfate pentahydrate) is bright blue and granular, and
can be found at pool, aquarium, garden
suppliers, and hardware stores under a
variety of brand names. Make sure the kind
you buy is pure copper sulfate (or copper
sulfate pentahydrate) with no additives.
Use a nonmetal stirrer to stir the solution until the salt and copper sulfate fully
dissolve. The liquid will turn clear blue or
blue-green [4]. Use the end of a wooden
dowel to crush the copper sulfate in the
solution to speed up the process.
NOTE: I prefer a dark patina, and that’s
the recipe I give, but you can get lighter,
darker, brownish, and purplish tones by
adjusting the recipe. After you’ve tried
the patina following this recipe, alter the
proportions of the ingredients to create a
formula that produces your desired results.
Apply the patina. Place your clean piece
into the gin-hurubi solution [5]. Slightly
agitate your piece throughout the process
to make sure you don’t trap any bubbles
on or under it; bubbles will hinder the
reaction and your patina will be uneven.
Let your piece rest in the solution for
10–15 minutes or until it turns dark brown.
NOTE: Place the glass container into
another container full of hot water to
accelerate the process.
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Remove the piece from the solution,
and rinse and dry it thoroughly [6].
NOTE: If the patina turns out too brown,
expose it to the sun to make it darker. If it’s
very dark brown or black, there’s no need
to expose it to the sun, but be aware that
the color may become darker over time.
If the color isn’t as dark as you desire,
clean the piece with baking soda again,
and place it back into the solution. If it’s
too dark, polish it with baking soda to
reduce the patina.
If the patina is uneven, remove it with
abrasive papers or heat the piece with
a reducing flame. Repeat the “depletion
gilding” step before reapplying the patina; it’s impossible to remove the patina
without removing the fine-silver layer.
NOTE: Since it’s made with vinegar, gin
hurubi has a high resistance to acid, so
you can’t remove it by pickling. (This also
means you don’t have to worry about
accidentally splashing lemon juice or salad
dressing on your jewelry while wearing it.)
Finish your piece. For added protection,
as well as for aesthetic reasons, I always
apply a paste wax (I use Renaissance Wax)
to my finished pieces .
Store and dispose of the patina. Store the used solution in a container
with a tightly closed nonmetal lid. It can
be re-used until it no longer works well
(see “Patina Disposal,” left). ASK THE ARTIST: KAZUHIKO ICHIKAWA
What’s your favorite local source of inspiration?
”I know some antique jewelry shops and a traditional Japanese
metal works shop in Tokyo. I often visit them to have a chance to
get in touch with the sense and skills of artists from olden days.“
Contact: [email protected]
Process photos by Kazuhiko Ichikawa.
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Bracelet by Lillian Jones
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