Here are some copper pendants before being oxidized.
I mix up my liver of sulfur solution in a plastic or ceramic dish, just enough to cover my metal pieces. The metal pieces should be clean and oil free for the best even coverage. The hotter the water, the better the blackening, although I only use water as hot as what comes out of the tap. At least once while the pieces are in the solution, I take them out and scrub them with a little soap, pumice and an old toothbrush.
Copper usually blackens easily. Sometimes I have to repeat the scrubbing and oxidizing several times to get a good consistent surface on bronze or silver. Most of the time I brush back the surfaces to the original color, except in the deeper crevices. I use the liver of sulfur as more of an “antiquing” or a way to highlight the textures in the surfaces. Here you can see a scotchbrite wheel that I use to brush the surfaces and how it’s started to show the golden tones of the brass vines on the leaf.
Here are the 4 copper pendants finished and ready to seal.
In these silver pieces, I’ve left very little of the blackening, just enough to bring out the texture on the silver pebbles.
Another patina that I’ve used in the past is ammonia fuming, to get a greenish patina on bronze and copper. When I use the ammonia fuming technique, I often oxidize the surfaces first with liver of sulfur first. Then I suspend the clean piece over a small amount of ammonia in a sealed container for 12 to 18 hours. After it achieves the level of blue or green that I want, or as close as it will go, I then burnish back to the original metal highlights and seal it with some sort of low-gloss acrylic spray.