I'm having problem with microballoons that i baught from alumilite. Im using pressure with my casts, about 40 psi. When i make a cast with the new microballoons im getting 25% shrinkage. I didnt have this problem with my old microballoons, there was a small amount of shrinkage but i could live with it. So my question is does anybody now what brand of micro balloons wont crush under pressure?