 Some
of the most frequently asked questions I get in classes and online are
about oxidizing metal with Liver-of-Sulfur.
Getting the patina process
down just right is an art in itself and something you can perfect over
time with much experimentation. To help you get consistent results,
write down what you've done so you can duplicate it in the future. Here
are some of my observations and answers to some of the more commonly
asked questions. I hope it takes some of the mystery and fear out of
using Liver-of-Sulfur.
What
is a patina?
A patina is a film that develops on the surface of metal over a period
of time. Due to exposure to open air and the natural process of
oxidation, an aged metal such as copper and bronze tends to develop a
patina. Ever notice the green color on copper roofs or weather vanes or
the lovely rich dark brown color of bronze statues in the park? Those
are patinas. The process by which a patina forms is called patination.
Because it can naturally take from days to years to occur, in wire
jewelry making we speed up the process so-to-speak and create the
patina we wish our jewelry to have. There are many types of patinas,
but today I'm discussing one of the more commonly used patinas,
Liver-of-Sulfur.
Always remember safety first!!!! Please be sure to wear protective eye
wear and gloves when handling chemicals or steel wool or whenever
appropriate. Use chemicals only in well ventilated areas or outdoors.
What
is Liver-of-Sulfur?
Liver-of-sulfur (LOS) is a very smelly, stinky :) sulfur product that
is a mixture of potassium sulfides. They are commonly used to turn
metals like copper and silver dark. It comes in the form of nuggets,
liquid and more recently, a new gel. I prefer the nugget form as it has
a long shelf life and is easy to use. I haven't tried it yet, but the
new gel form is supposed to last a long time and be easy to use.
You must store LOS in a cool dry place out of the sunlight. I have
found that keeping it in the container it arrives in, then placing that
in a zip lock-style bag and then that in a cookie jar etc. keeps it out
of harm's way and the local air supply free of the nasty sulfur smell.
It also keeps the items you don't want to oxidize safe from accidental
exposure.
Use tweezers or a plastic spoon to retrieve a nugget from the container
so that you don't contaminate the LOS with either wet fingers or the
oil from your fingers. A tiny bit of moisture in the LOS nugget form
will quickly ruin it. If it no longer smells...it's gone inert and is
no good. The fumes from the liver-of-sulfur you're working on can
oxidize the metal of the jewelry you're wearing, not just what's being
dipped, so be sure to remove all jewelry from your working area.
Application
Methods
The temperature of the LOS solution is very important in determining
the finished results you’ll get with the patina. A very hot
solution
of a pea-sized nugget dissolved in 1 cup of water will oxidize your
copper dark brown and your silver dark grey.
Fine silver takes longer to oxidize than Sterling. In a lukewarm to
cool solution, silver will stay yellowish to red for what seems like
forever! Temperature is the key here. You'll know you’ve got
it right when the silver immediately turns grey, not yellow.
By adding 1 teaspoon of ammonia to the solution, you’ll get a
very black patina. Too much ammonia, and you’ll get a
slightly reddish patina. I prefer the black look to the brownish color
LOS creates by itself.
By changing the temperature of not just the solution but the pieces to
be oxidized, you can create some lovely colors. The resulting yellows,
reds, golds, purples, etc. can be very beautiful, but they are not a
stable or permanent change. Left in the open air, over time copper
continues to oxidize and turns brown like a penny. To preserve the
patina, you must apply a protective coating. The only one I've found to
be effective for a long time and durable is Permalac sealant. Permalac
also prevents the metal from further oxidizing under the coating.
I’ve found that by tumbling my copper items first, then
adding the patina, letting them completely air-dry after putting them
in the LOS solution, and then re-tumbling, I get a very dark beautiful
finish. After removing from the tumbler I use a Sunshine Polishing
Cloth to buff, exposing the bright copper highlights on the raised
parts of my design and leaving a very dark patina on the rest. The
finished result is beautiful!
The copper earring pictured at the top right of the article shows the
black oxidized metal after 2 hours in the tumbler. The earring on the
left has been further finished with a polishing cloth. If you tumble
for a longer time, then the tumbling action starts to remove the
patina, creating a different look. I prefer the metal dark, but clean
and shiny. Experiment to get the color you like best.
With silver, I’ve found it best to remove as much of the
oxidation as I can using fine 0000 steel wool or a 3M pad while the
item is still wet because once it dries, it requires a lot of elbow
grease to remove. After buffing with the steel wool or 3M pad, rinse
and let tumble for several hours. This gives you a bright silver finish
with dark recessed areas.
To get a brushed antique finish, oxidize, tumble for 2-6 hours, then
buff with 0000 steel wool. Rinse and you’re done!
As to the LOS...if your solution is too cool, then the product will
build up on the metal causing an icky coating that will chip off.
It’s not actually bonded to the metal. A hotter solution will
help prevent that scaly build-up.
Contrary to some beliefs, you can oxidize items made with both silver
and copper...the copper does not prevent the silver from oxidizing.
However, the silver oxidizes more slowly than copper and by using a
much hotter mixture you'll even out the oxidizing time. If your copper
is getting black but the silver looks untouched or yellow, then your
mixture is not hot enough. If you leave your jewelry in waiting for the
silver to take, you’ll get that yucky build-up of oxidation
on the copper that flakes off. It’s messy and gives a poor
final product. Heating both metals before adding them to the solution
will help to keep your solution hot.
Important
Note
Keep in mind that when
putting a glass or gemstone item into a HOT liquid, you must first warm
them up. Do this by holding under a spray of hot water from your faucet
until the beads are warm or immerse in a bowl of warm water and
gradually add hotter water. You may then put them into the hot LOS
solution.
When the desired color is obtained, put the item into a solution of 1
teaspoon of baking soda to 1/2 cup water to stop further oxidation.
Then rinse with clean water.
You can spot oxidize by using a small paint brush or cotton swab and
apply the LOS only to the area you want it. Rinse and let it dry and
then buff the entire piece with 000 Extra Fine steel wool. Then, use a
polishing cloth. I prefer the Sunshine® brand. You may want to
buff with steel wool or dip in nail polish remover (acetone) before you
re-oxidize or add a lacquer coating in order to remove anything that
may be on the surface. Try wrapping your polishing cloth around a
pencil eraser and using that to buff the surface...it will help get
into the lower areas.
I recommend that you wear protective gloves when you use LOS to prevent
the chemical and SMELL from being absorbed into your hands. Also, the
gloves will prevent the black messy stuff and the steel wool fibers
from going into your skin. Also, use in a well ventilated area as
breathing concentrated fumes is not a good idea.
Have fun experimenting!
Do you have questions about Liver-of-Sulfur or other jewelry finishing
techniques? Ask
'em here!
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