Coloring on Oxidized Copper Question
I am trying to reproduce a handcrafted pendant made from oxidized copper. A beautiful picture was drawn on it with colored pencils, then sealed. So,I oxidized my own copper with liver of sulfate. Now that the copper is a nice black, I want to color on it with soft colored pencils. But, the black rubs off as I draw on it. How can I keep the blackened coat on the copper?