Hi guys. I have a pot of Smooth Cast 305 and I opened it about 6 months back to pour a tiny amount to create a test part from a mold. It looks perfectly fine still when I opened it, does this stuff ever go off, or is it just the mold max really? I'd like to mix it with a fresh batch I'm ordering and would hate to waste a good 0.80kg of it. It wouldn't damage my mold or anything?