My process is pretty simple, just takes time. Take your copper and clean all the dirt and oils off. I wear latex gloves when I do this so my skin doesn’t re-deposit oils. I use a scrubbing pad with a gentle scrub cleaner, and then baking powder with a half lemon. Do not use steel wool – it has oils in the metal fibers that will deposit back on the copper. A clean surface will take the chemical reaction to patina – oils will resist. *forgot to add- I take some sandpaper and rough up my surface. It will help the patina scales adhere better and will give more surface for the chemical interactions to work.* Once clean and the water sheets off, I start my process. You can leave the copper wet or let it dry – every time you do a patina, it will be different and every little variation in the environment can alter your results. This is the fun for me. For my box, I’m using a solution of white vinegar, ammonia, salt, and a little mustard. I let the solution wash over the sheet in a tray, then tilt to let the oxygen go to work. Maybe I’ll play around once or two – let some solution drip off my brush and wash off the green scale. A slow patina will last longer, so this isn’t a one hour process. For this batch, I let them sit for 24 to 36 hours. I could do longer, but I’ve decided this is the look I want for this project.
Once I’ve decided I’m done, I pick up the copper and with a soft scrub, I wash off the green scale. It’s soft, and when dry, would fall like powder. Under that is what I want.
I get some subtle color shifts as well as some of those blues and purples. Before I start riveting all my sheets together, I’ll give each a quick clear coat. All I’m doing is slowing down the oxidation process now. I’m just starting and stalling the process more on my own terms.