Fine Silver Inclusions
LauraJo, I’m not sure, because I haven’t done that much fusing. But with the Hi-Temp wire I think you can scrub it off with a wire brush or maybe some fine steel wool. Also, from what I’ve read, silver will stain some glass and also leave a "residue" on your shelf and then will stain or leave marks on other glass that’s fired on that same shelf.
I don’t know for sure what wire will stay nice when fired. They may all have to be cleaned somewhat after firing. Sorry I can’t help you more.