[If the copper deposit on your work is a dull, pink, putty color, your current is too low. It the deposit is really dark, powdery and grainy, your current is too high. What you’re shooting for is the look of a nice, new copper coin.]
http://www.lampworketc.com/forums/sh...ad.php?t=13716
Also the size of your anode (edit) and the distance to the work will make a difference
http://www.lampworketc.com/forums/sh...copper+etching
ETA etching the same process reversed