That’s what I used to patina some of my copper pieces recently. I dipped the metal in vinegar and placed it on a little rack inside a plastic container. I then sprinkled the vinegar-damp pieces with large-crystal sea salt. A shallow layer of ammonia covers the bottom of the container. The rack allows the pieces to sit above the ammonia to be exposed to the fumes.
The color started to show up within the first hour. I let the pieces sit for 24 hours.
I took them out, rinsed off the salt and let them dry. I sprayed the pieces with lacquer, rubbed them with preservation wax and then started to use them in some new earring designs.
In its final stage the patina ended up more green than blue.
I love seeing my own patina’d pieces mixed with other metals, but it’s one of those techniques I often put off. It’s as though I don’t want to have to go through the extra waiting time to develop the patina, then seal it, then wax it. My procrastination only serves to delay my gratification further. Oy! I really am my own worst enemy.