I'm having an issue with one of my glazes cracking as it dries on the bisque. The problem is worse when it is put over another glaze. This of course leads to crawling on the fired ware. I've tried using Veegum T to toughen it up, but not to much effect. I have just inherited some CMC, but I don't know how to use it. Is that a possible solution to this problem? Or do I need to do something else?