That Is a preview of membership content, log in by way of an institution to examine entry. Entry this informative article Dec 28, 2018 #seven The flat surface doesn't have to be glass, in fact glass just isn't that hard. It might be nearly anything relatively hard and flat. Go http://louisbdmb979.trexgame.net/11-faux-pas-that-are-actually-okay-to-make-with-your-silicon-carbide-crystal