Below the temperature at which PG changes phase from a solid to a liquid, I would think.Yeah, point taken though. I had that a little sideways. So the solids must be impurities that aren't soluble in PG, is what I'd guess if I were asked on a gameshow. But I'm not the one taking way more of a drug than I meant to if I'm wrong, so who cares what I'd guess on a game show really.