Apologies if this issue has been aired previously.
I melted 2 washers diameter 3/4" of new .3mm sterling sheet for granulation . One was a knobbly copper coloured oval with a slight patch of silver the other was a normal silver coloured ball. They stayed the same even after a time in the new/clean silver safety pickle pot.
Was this as someone suggested the result of heating in oxodising conditions? This does not seem chemically correct. I do melt and granulate fairly often and have never experienced this copper surface before. I use both charcoal and magnesite??? blocks.
I repeated the experiment with other off cuts from the same sheet and had the same mixed reults.Even filing the surface did not reveal shiny silver underneath.
Please can anyone tell me what is going on here.
Thank you