Repeat to hammer along the fold about two more times, or until a fin shape forms along the folded edge of the metal [Picture 4]. Don’t overwork the metal, or it may split.
After you’ve finished your last pass, anneal, pickle, rinse, and dry the copper.
Unfold the copper. Use your fingers [Picture 5] or flatnose pliers to unfold the metal. If necessary, place the fold over the edge of the bench block, and use the rawhide hammer to gently open the fold. You’ve just created this crazy ridge that sticks out of the sheet metal.
Anneal the unfolded metal, and pickle, rinse, and dry the copper.