Learned to appreciate the amazing beauty and versatility of copper. Have learned to etch copper using a particular ink (dye) and ferric chloride. Now need to know how to 'darken' the detail (negative) of the etching. At a recent art festival, we discovered, purchased from, and raved about an artist who worked primarily in copper. Her copper jewelry is amazing. I have been trying to get a similar look by stamping on copper, etching, and then trying to age it. I am not using the term patina per se as I know how to patina copper to produce many different blended and amazing colors (reds, greens, blues, yellows, etc). I need to blacken the negative of the etching so the image "pops", and I need to age the copper so it is not shining like a Greek polished brass mirror.