He used to be a plain old brass bug...
She's lovin' the new look...
They're the new kids on the block...
He's more than just copper now...
This is a different type of patina than the normally blue-green kind referred to as verdigris. It turns out salt is the key.
Here's how I did it:
-Solid brass or copper items (not plated base metals!)
-Large airtight plastic container with a smaller plastic bowl inside
-Plastic mesh - like a stitching canvas or screen
-Ammonia, clear or household without any added ingredients. about 1 cup.
-Plastic spray bottle with a small amount of salty vinegar water. The ratio isn't all that important as long as the salt is fully diluted.
Basically I placed the metal pieces on the mesh, on top of the bowl containing the ammonia, and sprayed lightly with the salt mixture. I closed the airtight container. I then wrapped it in a thick plastic bag since it wasn't all that airtight after all...
It can take like 48 hours to get a good color going and copper seems to take longer than brass. Once out I rinsed the pieces in water and let them air dry completely. They appeared much brighter after they had had time to dry. If it's not bright enough you can put them back in and spray on some more salty goodness.
The ammonia fuming method is basically the same used for creating a green verdigris patina but the added salt is what makes it turn blue.
-Ammonia is really strong and will clear out the worst congestion. If you're not congested you might want to prep all you stuff before hand and work on your stove-top with the fan on, windows open. You can actually set everything up and pour the ammonia at the last second through your pieces on the mesh.
-Items with small joints might totally be ruined if you do this. I'm not sure yet if it's just the ammonia, or the added corrosion caused by the salt, or just some low quality stampings, but some of them got really weak and any thin flexible joints basically broke off. Anything that was soldered on also broke off. I'm going to experiment using just ammonia to see what happens but it's best to use thick stampings with no thin dangly bits.
-Don't use items that have been plated, like brass or copper plated steel, or use anything that might contain it like a metal mesh or wire. If there's enough ambient heat it will copper plate your items - yeah I'm still trying to figure that out, but seriously, I plated some brass items in copper this way! It also stripped the copper from some other copper plated steel which could be cool if that's what you want. Chemistry...the more you know. Just avoid anything non-copper or non-brass.
-If it ends up looking really crappy and you want to start over just plop your stuff in pure white vinegar for a few hours. When they're back to their original color rinse off with water (or they will tarnish on exposure to the air).
Here are some links I compiled on the subject of aging metals including some Etsy threads:
How do you give brass a BLUE patina?