I bought a bag of shot at a show for cheap that was all white when I opened it. I poured it into a small bucket of water, let it soak good then agitated it a lot until the white stuff abraded off then poured it onto a cookie sheet I no longer use for cooking and let it dry in the sun for a few days. Wasn't sure at the time if the white stuff was arsenic or lead oxide, but perusing my references just now I see that there are no real lead oxides listed but there is an arsenic oxide, arsenolite As2O3, that occurs as white bloom or crust, so that may be what you see on shot. I wasn't aware that shot contained arsenic though, so other options are a hydrated antimony oxide - stibiconite. Shot likely contains tin but there are no tin oxides listed and I don't think Sn is easily oxidized. Bismuth also occurs as an oxide - bismite, but it's yellowish to greyish-green. There aren't any zinc oxide minerals that don't contain elements that I doubt would be found in bird shot, such as chrome and manganese, but then I'd not think there was arsenic in shot either, so what do I know?? I know I was afraid of that white dust the poofed out of that bag of old shot and wasn't about to breathe it. I wore latex gloves while dealing with the bag and tossed them when I was done. As for the issue of lead vapors coming off a melting pot, the vapor pressure of lead at the 700deg or so that we mold at is so low as to be inconsequential. I know we all get told that it's a huge issue, but according to the metallurgists tables it's not near as bad as we might think. Look it up. It's extremely low, almost zero. Regardless, I always cast my bullets outside on a sunny day with a crosswind. I would guess that the zinc fumes generated when you flux(if your flux contains Zn)the melt might be a much bigger issue than any lead vapors. Wheel weights are another issue, are very impure and can contain everything from Mercury to gold to zinc to you name it. I'd love to hear from our experienced metal guys on this.
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