One reason why Gerstley Borate can make glaze difficult to use
This glaze slurry contains 30% Gerstley Borate. I poured it onto a plaster table and it can take five or ten minutes to dewater enough to form it in test balls. A typical glaze would dewater twenty times faster! Gerstley Borate is like bentonite, it voraciously hangs on to the water it has. This is the reason that many GB glazes take a long time to dry on bisque ware. Generally slow drying also means cracking, that in turn can lead to crawling.