Pros : Easy to cut and shape, sands down well, holds up well after firing, and won't stick to the glass. I used this product to make a drop-out mold for use with a thick pot melt disk. It holds weight and leaves a clean surface. I was able to bevel the sides of the hole I cut in the board and sand them smooth for a nice finish. Quick and easy.
Cons : As expected, upon firing the board produces quite an odor. Ventilation is a must for safety.
Other Thoughts : This is a great product for making custom shapes without a lot of fuss.
Cons : This is the cheapest grade vermiculite I've ever seen, crumbles, dusty, guaranteed to wreck whatever you're working on . I bought it to confine casting pieces and found it a total waste. No matter how careful you are it will wind up in your piece.