I like the look of copper, but this versatile metal takes a long time to oxidize and until it does, it stands out like a shiny new penny. So on a couple of recent projects, I developed my own technique for jump-starting the oxidation process and creating that aged patina that I like.
I mixed up a potion containing one quart of water, one ounce of muriatic acid, and one tablespoon of salt, then sprayed the solution on a few test pieces of copper, using a typical spray bottle. That technique sort of worked—but the patina wasn’t thick enough and took too many coats, and I had to spray the test pieces every day for nearly a week. And the technique definitely wouldn’t work well on the copper pipes that I wanted to insert in an entry gate (see “Craftsmanlike Gate,” Jul/Aug 2015)—the solution just ran right off the pipes.
I couldn’t soak the pipes in the solution, either, because the reaction requires evaporation and oxygen. So I set the pipes in a wooden crate with layers of sawdust, poured in the mixture, and let my experiment sit outside for about a week. The solution slowly evaporated, the sawdust dried out, and what was left was copper that looked like it had been around for years.
I did the same thing with the copper panels in my living-room cabinet doors. I stacked them in layers—soaking the sawdust between the layers in the acid solution—then set the box outside to dry. Worked like a charm.