I'm thumbing through Michael DeMeng's DUSTY DIABLOS and see this product he uses (p. 75) that's called mica (not the powder--I'm talking about the sheet variety). He uses it as a "window" (often treated with paint washes) in many of his pieces, and I love the mysterious quality it gives the images behind it.
Has anyone ever used this before? Positives and negatives? If you have used it, where's a place (store or on-line) to buy it?
I think I found what I'm looking for. It's a mica tile product from Art Quest.