I hesitated about making this post. Some people might find the topic somewhat unpleasant. However, it concerns a way to obtain a lovely color in your copper jewelry. If done properly, there is nothing unsanitary about it. Therefore, I decided to go ahead.
We all know how to apply a black patina to our copper jewelry (BlackMax works wonders, although there are other approaches). Baldwin’s Patina gives a lovely brown. Salt and ammonia produces a vivid green. But how about blue? Surely you have seen some copper architectural detail or a copper piece in a museum that has a vivid blue color. I’m going to tell you a way to get that color (caveat: I’m sure there are others, but this is the one I tried and it worked for me).
To start off, I made a pair of copper earrings, with an Andean design of a two headed condor. I’m not sure what the two-headed condor symbolized to the ancient people of the Andes. I would be curious to know if anyone can tell me. In any case, the earrings, fired and tumbled, appeared as follows:
There is already a touch of a green patina on one of them. That sometimes appears on copper jewelry, and I do not know how to predict or control it.
Now for the step that produces the vibrant color. Do you have a cat? Do you ever use the silica litter? If you do, and you haven’t changed the litter box in several days, a layer of ammonia-smelling grunge develops at the bottom. I don’t have to tell you what produced it. When you change the cat box, scoop some of this out and transfer it to a container. It would be best to not touch the used cat latter. You can either wear disposable gloves or simply be careful when you transfer the cat litter. I used a resealable plastic bag as a container, but any container to which you are not too attached will work.
Then, using a pair of long tweezers, I submerged the copper earrings in the used cat litter. I left them in place approximately 24 hours. I removed the earrings from the cat litter using the same long tweezers. The process had worked — the earrings were deep blue! The patina had grown to such an extent that it had closed off one of the openings in one earring. This was easily fixable by inserting a copper wire into the opening, removing the patina that had sealed the opening.
I then washed the earrings in running water until no trace of the ammonia smell remained (and washed the tweezers). Be sure not to scrub the copper, because the layer of patina is still somewhat fragile. Leaving the copper under a stream of running water for a few minutes is quite sufficient.
The patina covered the whole of the earrings, making the pattern invisible. I fixed this by gently rubbing with a fingernail sponge (available from any beauty supply store). This removed the patina from the condor, while letting the patina remain as a background. The patina did not want to come off the condors’ eyes. I removed this part of the patina with a metal burnisher.
To make the patina permanent, I sprayed the earrings with a fixative. I generally use the same metal fixative the players of brass instruments use to keep their instruments from tarnishing. However, any protective surface that can be applied with a spray (so you don’t remove any patina) will work.
The finished product, with a coin for scale, appears below.
The person for whom I made these loved the color. There was no trace of smell, and the client had no idea how I had colored the earrings (until I told her).
What if you want to try this and you don’t have a cat? Surely someone you know has one. Other species would probably work as well, but cats (due to their use of a litter box) are easy to deal with.
I encourage you to try applying this bright blue patina to your copper work. Don’t be squeamish about the source of the color. There is a bit of work involved, but the results are well worth it.