This is a description of the electro-etch setup that I use for etching jewelry-size pieces of silver and copper for enameling. There are a lot of different ways to do this technique, so I hope you will feel free to adapt any ideas here and apply them to your own setup. This technique is really very simple and I hope you will be inspired to give it a try.

  While the chemicals and electrical equipment used in the process I describe are relatively benign, please familiarize yourself with proper chemical handling and electrical safety procedures before starting a project.

If you would like to understand the basic electro-etch process, here it is in the simplest (barely scientific) terms. The artwork (also called the anode) is positively charged by the rectifier (also called the power source) and another “thing” (called the cathode) is negatively charged by the rectifier. The anode and cathode are submerged in a liquid that completes the electro-etching circuit, the current is turned on, and little flakes of metal that are not protected by a resist travel in a straight line from the anode to the cathode. The resulting voids are the etched areas we seek. Different things can be the cathode and different things can make up the liquid. So if you are reading other descriptions of electro-etching, keep in mind that the basic process is the same.

I use a stainless steel pan as the cathode. The negative clip (Black) from the rectifier is attached directly to the pan. I put a wooden dowel wrapped in double-sided carpet tape across the top that will support the positive clip (Red) which will be attached to the artwork.

To prepare the liquid for etching silver, mix 750 ml distilled water with 15 grams of silver nitrate crystals. Use gloves because the silver nitrate will stain your skin. To prepare the liquid for etching copper, mix 750 ml distilled water with 75 grams of cupric sulfate crystals. I store the liquids in closed containers between etching sessions and I filter through a coffee filter before storing. The flakes of silver will freely come away from the stainless and can be retrieved from the dry coffee filter for scrap.

This pile of silver flake was retrieved after etching 4 or 5 small pieces.

The copper will plate the stainless and once it builds up a bit I have to peel it off to reveal the plain stainless again. As I notice the level of liquid getting lower I add distilled water and a very small amount of chemical to restore the bath. I don’t have the sense that an exact chemical balance is important.

I make a connector for attaching the artwork to the red clip from the power supply. The connector goes in the etching liquid and the clip stays dry. The connector looks something like a garden hoe, and I use scissors to cut it from 26 gauge copper. The hoe end is ½” x 1” and the handle is ¼” x 5”. I protect the lower end of the handle with plastic electrical tape. Before attaching the hoe to the art, I sand the copper to assure the electrical connection and then tape it to the center back, covering all of the exposed metal. I trim any tape overhang and then seal the metal edges with nail polish. I also put polish on the bend of the hoe where the handle tape stops at the bottom. These connectors usually last for 6 to 8 etchings.

On the left is a connector ready to be attached to artwork, and on the right the connector is
attached to the art with plastic electrical tape and the edges are covered with nail polish.

I attach the connector of the artwork (anode) to the positive red clip and position it so the face of the image is about a half inch from the bottom of the pan and parallel to it. If part of the artwork is closer to the cathode (the pan) it will etch faster, so I always check to see that the art is parallel to the pan bottom and bend the handle if I need to adjust it.

Now that I have the pan connected to the black clip and the art connected to the red clip and positioned parallel to the bottom of the pan, I am ready to adjust the power source.  I turn the bottom knob marked "voltage" all the way to the right and the upper knob marked "current" all the way to the left.  Now I turn on the power source and slowly turn the upper knob to the right until the digital readout is approximately 1.0 amps.  Immediately little flakes of metal begin falling off as the etching begins.  If you set etch at a too high setting, for example 1.5 amps, the edges will be ragged.   I set a timer for 10 minutes and every time it goes off I unhook the art and rinse it under the faucet. The sludge easily rinses off the unprotected areas and the resist is unaffected by the flow of the water. I also use an old brush to clear away the sludge on the bottom of the pan.  I reposition the art and etch another 10 minutes. I shut off the rectifier while rinsing the sludge.  Cleaning the sludge significantly decreases etching time.

While working with the system, be aware of the possibility of a short and do not let the red and black alligator clips touch each other.


I get a .4-.5mm etch on silver in about 40 minutes. I typically do pieces that are 11/2” x 2”. Copper takes about 50% longer. The etched edges are vertical (not undercut) and there is slightly deeper etching near the resist than in open spaces. The solution does not get weaker each time so etching time for a given design remains constant. I have used the same solution for years, never remaking a new batch.  It is very satisfying to work with this system because of the speed, detail, and relatively friendly chemicals.


Supplies

Stainless pans used for steam table inserts are available from restaurant suppliers.  Winco is an inexpensive brand.  A Google search will produce a number of options.  Note: If you want to etch copper and silver, you will need a separate  pan for each process.  “Sixth Size 4 inch depth" is the size shown in the photos and will accommodate most jewelry size art.  If you want to etch bangles, order "Third Size 4 inch depth."

Wooden dowel, double-sided heavy duty carpet tape, and plastic electrical tape can be purchased at your local hardware store.  Grainger has economical very large rolls of electrical tape.

26 gauge copper sheet can be purchased at RioGrande.com or your usual metal supplier.

Silver nitrate and cupric sulfate crystals can be ordered from ScienceCompany.com. There is no hazardous shipping charge.

I use and recommend this well-priced rectifier http://www.multimeterwarehouse.com/HY1803dLf.htm. To make the leads, buy alligator clips, 1/4" ring terminals and low voltage wire for car radios at a builders supply such as Home Depot.

I have attached artwork for cutting out "hoe" shaped connectors from copper for suspending art into the etching solution.

Hi Vera,

Great explanation. Thanks.

Here is a particularly informative article about electro-etching: http://www.nontoxicprint.com/electroetching.htm. Although the author is dealing directly with printmaking, he covers in detail health and safety issues and makes detailed comparisons with acid etching.

One piece of information that I learned was that if one were to run at very high voltage (around 10 volts) dangerous, potentially explosive gas could form. Keep the voltage at 1, 2 or 3 volts.

I recently sent scrap silver to the refiner and included 3 ounces of fine silver particles recovered from electro-etching. The refinery called me to say that they weighed the overall shipment an ounce less than I had weighed it, and mentioned in passing that since I had a fair amount of fine silver scrap they wouldn't impose the penalty charge for including "sweeps." Whoa! I quickly explained that the fine particles were not general studio trash but rather fine silver. Lesson learned: If you send in your particles, contain them and label them clearly with a full explanation...the refiners are used to charging extra for processing "sweeps" that contain all manor of other materials and they don't like them mixed in with the silver scrap.

Vera, I've done electro etching before, but not for silver.   In the past I've etched copper and used another sheet of copper for the cathode because I thought you had to use the same metal.  This is great that you can use stainless.  I've ordered the chemicals but don't have the containers, thought I'd try just using a piece of stainless for a cathode.  Is there any reason that won't work? 

Thanks for a great tutorial.

Mary

 

Technically, it should work.  You will have to figure out another way to set it up. 

I will say that the reason I like the stainless pans is that cleanup is so easy.  When I'm done etching I pour the silver nitrate liquid back into a plastic container by pouring through a sieve with a coffee filter.  I cover the plastic container.  I let the coffee filter and the stainless pan dry until the next etching session.

Then when I'm ready to etch again I pour the dry silver granules from the coffee filter into another storage container.  Then I take my little metal spatula for moving pieces of enamel and scrape the sides and bottom of the stainless pan to loosen the dried silver granules and pour them into the storage container.  Ready to go.  (By the way, if one were to allow the silver granules to build up and not clean them off, they would provide an insulating effect and etching would stop.) And, in case you're wondering, during this dry cleanup stage I don't get any staining of my fingers from the silver nitrate.

Hey Vera, Have you used Ferric Nitrate instead of Silver Nitrate for electro-etching? Or Nitric Acid?

Ummm, interesting question.  Electro-etching works because the electricity is passing through water enhanced with salt--ideally the chemical "salt" of the metal being etched.  Therefore silver nitrate for silver and cupric sulfate for copper.  You can also find directions for electro-etching copper with table salt (but that doesn't work on silver). 

So part of the answer is that one wouldn't electro-etch with ferric nitrate or nitric acid because they aren't the chemical "salt" of the metal being etched. 

Also, ferric nitrate and nitric acid etch metal without electricity, and adding electricity wouldn't make them etch more...or maybe would make nitric acid more hazardous...I have no idea!

But the other part of the answer is that the really desirable aspect of electro-etching is that you don't have to use the "nasty" chemicals.  Ferric nitrate is quite a mess to work with and dispose of since it gets weaker with use and has to be thrown out.  Nitric acid is dangerous.  Some people don't want to etch because they are worried about chemical exposure to themselves and the environment. 

The chemicals used in electro-etching are relatively benign and non-fuming, and they don't have to be disposed of because they don't wear out with use.  One can, with basic common sense and hygiene, do electro-etching with essentially no chemical exposure.  And no environmental impact.

And, I have to say, I'm not a scientist, so if I said something wrong here I hope somebody will jump in and correct me. 

Dear Vera,

I was very interested to read your excellent article on your electro-etching.

You may be interested to know that I use copper nitrate for electro-etching copper and use a formula to work out how much current to apply and for how long to etch to a prescribed depth.

Probably a rather pedantic approach ! but it works for me.

Regards,

 

Raymond Jackson

That's wonderful.  Please post.  There is so little information on electro-etching and it seems we are all finding our own way.  I love that you are so scientific in your approach.  I just turn it on an have "faith" that it will work.   And then I quit when it's "done." 

Also, I'm sure people would love to see pictures of your setup and learn of any little tricks up your sleeve.  So glad you joined the group!   vera