Safer Silver Etching

I have been desperate to try out silver etching for a long time. I love working with etched copper and wanted to create the same effects on sterling. The only problem was the chemicals involved in the process. Usually silver is etched using Nitric acid, a highly toxic and corrosive liquid which emits harmful gases while eating away at the metal. As much as I love undertaking dangerous activities, the thoughts of messing around with strong acid worry me. So I’ve been looking for a safer alternative. 

My research started off looking in to different solutions for stripping the silver, I found ferric nitrate and silver nitrate. I have silver nitrate in my ever growing collection of raw materials for glaze mixing so I decided to go with that. Silver Nitrate is still a hazardous substance and should be treated with care. I wear a mask when mixing it and rubber gloves. Silver Nitrate won’t do any harm if it touches your skin as a diluted solution, it’s actually used for certain skin treatments, but it will stain your hands a lovely shade of brown, it won’t be apparent at first, but it’s light sensitive so the minute you go out in the sun, they will change colour… ask me how I know! It is also dangerous if you get it in your eyes. Always take proper safety precautions and use common sense!

To etch with silver nitrate you also need a power source and a few other bits and bobs which I will tell you about as we go along. The power source listed was a bench supply, I have one of those, but I wanted to try and see if the process worked the same as salt water etching, so I'm going battery powered!

So to start, I cut as close to a circle of silver as I could, and also cut a dreamcatcher design in vinyl to use as a resist. You can use all sorts of things to mask with, pnp paper, stop out fluid, and ironed on toner. But I haven’t had chance to test how they work yet, so I went with what I know! 

Here’s the silver ready to go with the areas I don’t want to be etched masked out. I also masked the back of the disc.

The silver piece needs to be suspended in the silver nitrate solution, so for this I used Aluminium wire wrapped around the edge so it was touching the silver and taped it on from the back.

The other supplies needed are a steel bowl, (I used a small water bowl from the pet shop) a D size battery and holder with terminals (not sure of the proper name for that!), a couple of crocodile clips attached to the positive and negative of the holder with copper wire, and a bamboo skewer.

100ml of water was put in to the bowl and I added 1 gram of silver nitrate. Always add dry ingredients to wet to save splashes! Stir with an old spoon until the crystals have dissolved, and the mix is ready to go. 

The bamboo skewer is placed across the bowl and the aluminium wire bent around it to suspend the silver so that it’s fully submerged, but not touching the metal of the bowl. 

The negative wire from the battery is clamped on to the metal bowl, and the positive is connected to the aluminium wire to complete the circuit. Once both crocodile clips are attached to the battery, the etching process will start. It’s not as fast a process as if you were using nitric acid. I left the silver in for about an hour to get a shallow etch, it could have probably done with twice that! 

If the etch is working you will see a grey fur appearing on the wire and the silver. You can see here how dirty the solution gets as it etches. To reuse it, you need to strain all the bits out and pour it into a bottle for storage. (I swapped the wire over before this picture for copper, as I wasn’t sure if it was working. I didn’t realise that the aluminium wire was coated, so after sanding it off, I switched back and it worked fine!)

I’ve been looking around for information to dispose of the solution and bits safely. When you’re finished with it, the solution can be neutralised using table salt. The advice given is to add salt until no more white precipitate is produced and then hand it over to your local hazardous waste disposal facility, the same as you would with ferric chloride used for copper. It has also been suggested that as it is silver, photography shops can help you get rid of it safely, as they send in their spent chemicals to companies that recover the silver.

So after the hour, I couldn’t wait any longer and took out the silver piece. 

This is how it looked when I first took it out. After a scrub with a scourer, I treated it with liver of sulphur to bring out the texture and sanded back lightly to reveal the pattern.

This attempt wasn’t deep enough to polish, when I tried it lifted all the patina off again, but I quite like it as a matt textured piece!

I can’t wait to try this out again and experiment, I can now do all the things I’ve tried in copper, but in Sterling silver!

Caroline

http://www.blueberribeads.co.uk