I guess this phrase can be used both ways lol. Anyways, in all that discussion I didn't notice anyone mention that you have to make sure you scrub the copper with Acetone (nothing else works as well) an something abrasive like steel wool (but not steel wool). I use the green dish washing pads. I have tried using degreasers, lacquer thinner, rubbing alchohol...nothing else works as well as acetone. And wear clean nitrile gloves too. Fingerprints have a lot of oils in them.