I taught at the John C Campbell folk school this weekend. I had a fantastic time with a great class. Here is a copy of my handout from the class. I’m going to be teaching the class at the folk school again next June. I will post a link for the class when it becomes available. – Liz
Salt Water Etching Class notes- Liz EvansI learned the basics for this technique from the article: “D Battery + Saltwater = Cheap, Acid-Free Etching” by Ron Pascho published in the Art Jewelry November 2008 issue. It is a great article and I highly recommend reading it.
I moved from single D battery setup, described in the article, to a two battery holder with rechargeable batteries, and finally to a cellphone charger. The principle is the same. You need the following:
1. Power – Battery Holder + Batteries OR a charger. You need to have access to the anode (Red +) and cathode (Black -) wires.
2. Salt water – Super saturated solution (this works better if you make it up ahead of time.) I use Kosher Salt or Pickling Salt. You don’t want Iodized salt.
3. Copper plate to attach to the cathode (-) Black wire. This should be slightly larger than the piece you want to etch. This piece is reusable and only needs to be cleaned and well dried between uses.
4. Copper, Brass, bronze, or nickel silver piece that you want to etch. Attach to the anode (+) Red wire.
6. Copper wire, 18-gauge. To attach the pieces to the wires.
7. A Resist – Nail Polish, Paint, Pain Pens, Permanent Marker, PnP Paper, or tape.
8. A non-conductive rod to hold your anode and cathode in place over the solution. A wooden dowel or bamboo skewer.
9. A non-conductive container to hold the solution (plastic or glass work well).
10. Cleaner to remove the resist and to initially remove oils from the piece. Barkeeper’s Friend or Penny Bright.
A night or two before you want to etch mix up your saltwater solution. Start by pouring out about 2 cups of water from a gallon of distilled water into a pitcher for later. Mix in 2 cups of pickling salt into that gallon jug of distilled water. Put the lid on and shake well. Let it rest for a few minutes and then shake again. If all the salt dissolves add more and shake again. Keep adding salt and shaking the jug until it stops absorbing the salt. Let it sit overnight and then add more salt and shake in the morning until a fine layer of salt stays on the bottom.
You can attach the anode and cathode wires directly to the copper / to etch pieces but I bought some stranded insulated copper wire with alligator clips to make extenders that could be cleaned or easily fixed if they got eaten through or rusted out. You could also just twist the anode and cathode wires directly to copper wires.
I used to say to clean your piece first but now my recommendation is to go ahead and attach your copper wire to both your cathode piece and your etching piece.
Take a copper wire and tape it to the back of your to etch piece. Cover the entire back of your piece with duck-tape. , unless you want the back of your piece etched as well. In that case you will need to plan for a space at the top of your piece that you can drill a small hole in for the wire to go through. The cathode copper piece only needs the wire taped or soldered to it you don’t have to cover the whole back with tape.
The piece that is going to be etched must be cleaned. I used Barkeeper’s Friend and a green scrubby to get all the oil off the face of the piece. You have to clean them until the water sheets off the metal. If it the water pulls away from the sides it still has oil on it, so keep scrubbing until you get a nice even sheet of water on the metal when you rinse it. Dry it off with paper towels and then don’t touch the front of the piece if at all possible. The duck-tape should hold even through the wash, but check it to make sure that it is still secure with no gaps. The wire gives you a hand hold.
Decorating: If you are attaching your copper wire using a hole you leave the area around the hole bare, don’t cover it and don’t paint it. Paint the edges and your design on the front with a paint pen or other resist. Cover all surfaces you do NOT want recessed/etched. You could also use a sharpie marker but I find that it wears off about half way through the etching process.
I cut bamboo skewers in half to lay over the top of the glass jars. They help with securing the wires in the right areas of the jars. I put a ~ 2in piece of copper onto the exposed end of the cathode wire (- black wire). I then attach the anode wire (+ red wire) to the piece you want to etch. Use the bamboo pieces to help hang both pieces so that they are parallel with the side with the design facing the copper cathode. If you don’t have a dowel or skewer you can hang them off the sides of the jar. They work better the closer they are to each other without touching. Fill to cover the pieces with salt water. Put the D batteries into the holder or plug in the charger. (Some cell phone chargers are smart so they know when something is plugged in or they take a few minutes to build up a charge.)
If you are etching a bead or both sides of a piece you will want to hang cathode pieces on either side of your piece, effectively sandwiching your piece between them without touching it. You would then connect both cathode pieces to the same black wire from your power source.
You should see bubbles. Lots and lots of bubbles. If it is going well it will look kind of like an Alka-Seltzer going. The cathode piece will be the one fizzing. Which seems counter intuitive but is correct. Your etching piece will not fizz. The water will also start to turn really, really muddy orange. Let it bubble for an hour checking and wiping it the etch piece off every 15 min. I wiped off both the anode and cathode pieces. Check to see if you need to re-apply any resist. The larger your container the longer the etching will take.
Once the piece is etched you can peel off the duck-tape backing and scrub off the paint with a green scrubby, brillo pad, alcohol, or nail polish remover.
Let the water stand in the jars overnight. The precipitate all falls to the bottom. You can continue to use the same water until it stops fizzing.
So what is it actually doing? You are making a circuit. The power source attaches to your + anode and –cathode plates. The salt water then completes the circuit. The electrical current flows from one plate to the other through the solution. This electrical current strips electrons away from the anode plate. The electrons are only pulled away from the exposed portions of the anode resulting in a recessed design. Each atom becomes a water-soluble copper ion that either combines with a chloride ion in the solution to form cupric chloride (Copper II chloride, CuCl2) or it attaches to the cathode where it looks like a thin coating of metal. You will want to dispose of the copper salts appropriately.