A trip through Seattle a few weeks ago yielded an expensive stop at Seattle Fabrics (neoprene, boat cover material) and a much cheaper stop at the Boeing outlet store, where they had a roll of satin weave glass cloth. It was pretty cheap by the pound and I bought a lot of it. I'm sure that the project list will expand to accomodate it, but I'd like to know just what it is that I have. I can easily weigh a fixed amount to get that information, but can anyone tell me how to tell the difference between s-glass and e-glass?