Reply by Tennessee

I’ve used two pieces of tempered layered glass for the last 30 years. Easy to tote around, flat, no problems. I keep 180 grit taped on one for sanding down small wooden items and plastic things, and the other has 400 on it for doing edge sharpening. I would think though, that granite should be true, but there is no law I know of that describes flatness requirements for things like sink cutouts. Still, I would not turn down a piece of granite.

-- Paul, Tennessee, http://www.tsunamiguitars.com