I have casted my own sheet anodes from some zinc pellets (99.99 %pure) and started up my bath today. I was doing everything as i always do cleaning, rinsing pickling and so on. I plated one batch, beautiful results. Started up a second one, went inside the house for some coffee and returned to the plating tank after 15 minutes. I looked in the tank and thought, hmm… thats strange, the electolyte seems to have a blueish coulor to it. With a closer inspecton i noticed some blue powder like stuff on the side of the tank (waterline). I took out the parts i was plating and discovered that they had black spots on them.
What the heck has happened?! I belive its a copper contamination, but how?? Could copper have leeched in to the anodes when i casted them? I didnt use any copper i the casting process…..