by Virginia Vivier.
(Esprit Mystique Jewelry)
Acid Etching Brass and Copper Jewelry
Part 3a: Ferric Chloride Acid Bath
So far in this 4-part series of articles, we’ve covered two different ways of preparing your brass or copper piece for etching in the acid bath:
Here in Part 3 we’ll cover how to etch your prepared piece of brass or copper in the Ferric Chloride acid bath.
Ferric Chloride is not a dangerous acid, like Nitric acid or Hydrochloric acid. All it does is make metal rust.
You can safely neutralize it with baking soda and pour it down the drain, or in the ground.
But it does leave dark stains on your hands if you touch it, so use rubber gloves when working with it.
And of course, keep children and pets out of the area at all times.
I forgot to cover a small container of Ferric Chloride that I re-use for etching in my workshop.
I found that (over time) a pegboard stocked full of tools, screw drivers, wire cutters, scissors, and other metals containing iron, mysteriously rusted much faster than normal. (I live in Tucson, AZ where we have a very dry climate and rust is rarely a problem.)
So, keep the container of Ferric Chloride covered, or store it away from tools. If left uncovered for more than an hour or two, it may evaporate into the air and attack tools containing iron left in the same room.
This is my very own personal unscientific theory. So take this advice FWIW.
Where to buy Ferric Chloride:
Ferric Chloride is used by copper circuit board designers.
Radio Shack used to carry Ferric Chloride in pints. But they no longer carry it in Tucson, AZ.
I buy it, by the gallon, from a chemical supplier here in Tucson.
If you order it from an out-of-state supplier, they will add substantial HAZMAT shipping charges, so it is best to find a local chemical supplier.
Many electronic specialty stores carry Ferric Chloride. I have purchased it in crystal form, which works fine too, but I can’t remember the ratio of crystals to water.
So if you buy it in crystal form, ask your supplier what quantity to mix with water to make a solution that will etch brass or copper quickly.
This bottle of liquid Ferric Chloride (below) is what I am using now. It works great, full strength, straight out of the bottle:
I store the brown glass gallon bottle in a cool, dark place, as sunlight will weaken it. You can cover it with a black plastic garbage bag, but make sure you mark it so no one bumps into it accidentally.
I have had this bottle for over a year and it hasn’t lost any strength.
Make sure your Ferric Chloride bottle has a plastic cap.
Never use metal caps on Ferric Chloride containers.
I only use about 3 cups at a time, and keep reusing it until it takes longer and longer to achieve the same etch results.
Then I throw it out, and start over with a fresh batch.
When I use a fresh batch, it will deep etch my copper and brass quickly, in about 30 minutes, so it is good to set a timer and check the etching progress often.
After you have used the same batch about 10 times, it will take about 30 minutes longer to achieve the same depth of etch, depending on how many pieces of metal are in the acid bath.
I read an article about adding a teaspoon of powdered Ester C to 3 cups of Ferric Chloride to maintain its strength, and it seems to be working. You can buy powdered Ester C at any drug store:
ester c for ferric chloride used in etching metal jewelry
Also be sure to see the new page, Acid Etching Metal Jewelry – UPDATE before beginning your etching project!
Questions or comments on Part 3a? Please ask!
Thank you . . .
For the helpful tips on where to get these items – and the caution about avoiding the HAZMAT shipping fee!
I could do this
I am scared of chemicals and have always felt they are dangerous, but after reading your information and tips I feel I really could do this. Thank you for explaining it so clearly and for giving ideas for spending less money on them.