My first experiment was to blue copper using ammonia. I got the idea from BeadStyle magazine.
I decided to try it on one of my copper byzantine link keychains. I carefully cleaned and polished the keyring to ensure the patina would cover the copper evenly.
I soaked the keychain for about two hours in a solution of salt water. Then I lightly patted it with a paper towel to remove the dripping salt water. I then suspended it on a bamboo skewer in a plastic container with about a half inch of ammonia in the bottom. I closed the top securely and let it sit for about two hours. Within ten minutes, the copper darkened and started to look really nasty. I was a bit concerned about whether it would turn blue or black.
After about and hour I started to see bits of blue developing. However, the majority of the copper was still a nasty blackish color. The water in the container also started to take on a blue cast.
After two hours, there was quite a bit of blue on the copper rings. As it dried, the blue lightened up to a beautiful rich turquoise color.
Important Notes: The copper must be cleaned and free of all chemicals. Do not use a commercial cleaner such as Never Dull or the patina will not stick. The patina is fragile and flakes off with handling. I rinsed the piece and allowed it dry several times. Some of the blue flaked off, revealing the lovely darkened brown beneath. I recommend sealing the finished piece with a matte sealer to preserve the patina and keep the weathered look. If you prefer, you may use a gloss sealer to give the finished piece a lot of shine. If you plan to incorporate the finished piece into a larger work, please note that the patina is a surface finish and will easily scratch off with tools, so be gentle and plan your work carefully.
My next patina experiment was to heat color copper. This is a particularly lovely technique that I have long admired. There is a great blog by the Etsy Metal Team explaining this process in much more detail. It is typically done with a torch on sheet copper. However, I use heavy gauge copper wire in my work and have a six year old little boy who helps me with my work. The use of a torch is simply not an option for me at this point. After much thought and an idea given by a fellow Etsian, I decided to try a heat coloring experiment using my electric oven.
I have a pair of earrings and a spiral neckwire that I wear quite a bit. I decided to use these pieces for my heat experiment. I set my oven on high broil, moved the rack to the highest level and made a little aluminum foil tray to place my earring component on. Making sure that the copper was directly beneath the heating element, I broiled my earring components for about 10 minutes, checking frequently to ensure the color didn't go beyond the pink/purple shade I was shooting for. As soon as I saw the color I wanted, I very carefully placed them on a piece of cardboard in my freezer to quickly cool them and lock in the color.
The neckwire was a bit trickier as it is shaped to sit smoothly around the neck. I wanted the color portion to be focused on the spiral, not on the curved sides. I ended up carefully positioning the neckwire through the wire of the oven rack so that the spiral portion was fairly flat under one of the heating elements. I broiled it for about 15 minutes as it was a bit thicker than the earring components. As soon as I saw that gorgeous pink/purple color, I carefully placed it in on the cardboard in my freezer and allowed it to cool for about two hours.
All in all, I am very pleased with my first attempts at heat coloring copper...especially as I was improvising with my tools and techniques.
Important Notes: As with the bluing technique, it is very important that your copper be clean and free of all chemical residue. I often use Never Dull to clean my copper pieces as it leaves a slight protective film. I did not get all of this off the first time I attempted to heat color my earrings and I ended up with a very unattractive mottled brown finish. I was able to clean it off, but the heat combined with the chemical left a pitted surface on the copper. If you do not achieve the color you want, you can buff the surface clean using emory cloth.
I lost a great deal of the pink/purple color as the copper cooled. I am not sure how to resolve that issue, but I am still researching and experimenting. Many people recommend using Rennaisance Wax to seal the pieces after heat coloring. I have not done this yet as I don't have any Ren Wax on hand at this moment.