Thanks for the info! Not what I really wanted to hear, but at least I didn't have to ruin anything from my precious horde by testing.
Chicago Art Glass has been back in production for a couple of years, unless they have closed again. You can buy their glass and tiles at Art Glass Plus.
Has anyone here played with Yough. stipple glass or CAG in the kiln? I know mottled glass loses its mottling, but I'm wondering about stipple glass and opaque CAG.
How does the color and character of the glass stand up to slumping? How about fusing (to itself, of course)?