I've discovered that when I'm heating Argentium sheet, flat on my silquar board (the boards that look like a bread or pizza stone), I not only get a very darkened piece (despite using a mapp gas torch), but that I also have trouble getting pieces up to fusing temperature. Yet, the same piece, when curved up off the board, heats up quickly, no oxides and fuses easily. I have no trouble using easy solder, but some trouble with hard. I'm going to ditch that board and try a hard charcoal block. However, I also noticed, on a supplier's website, annealing pans with pumice. Any pros/cons for using something like that for Argentium? I'm thinking that the pumice shouldn't leave a mark in the Argentium but could be wrong'
I like the silquar blocks for fusing wires together, or for making
granules with flat bottoms— but otherwise, they suck up too much
heat. My preference is a Solderite board, which is much more heat
reflective. (Ronda Coryell prefers charcoal.) Pumice would work, but
I would not use it for flat pieces of Argentium Silver, which have a
tendency to sag. Pumice would be fine for annealing formed pieces.
FYI-- the darkening on the back side of the AS when you use a flat
piece on a silquar/ceramic board, that is because the flat board
against the flat Argentium Silver did not allow enough oxygen to
reach the surface to combine with the germanium, to make germanium
oxide. The darkened surface comes off in pickle.