As glazes and underglazes age, the binder can break down causing peeling, crawling and cracking. By adding gum solution one tablespoon per pint at a time, you can slow the drying time of the glaze making it brush easier and diminish cracking and peeling issues. Continue to add gum solution a little at a time until the problem is resolved. You may need to add additonal water as well to regain the right consistency for brushing (CMC based).
Dry glazes are formulated as dipping glazes and need gum solution to make them brushable. Once the glaze has been made, add ½ cup of gum solution per gallon of glaze.