I want to thank everyone for their responses. Very helpful. I actually have the Hamer book and the section on cracks is great. Years ago,I used the formula "Rhodes" celadon for my blue celadon glaze. This glaze has a lot of Cornwall stone, which I thought may be the problem. It started to craze in the manner I described, so I increased the silica, but the problem persisted. I was frustrated and chose to test other celadons, and found another beautiful one, which is the one I am now struggling with. This may be a silly question, but does the addition of bentonite lower the COE of the glaze? This glaze sinks to the bottom almost immediately when mixed, so I've been adding perhaps too much bentonite.
I'll be researching on Digitalfire per Hulk's links. Thanks so much for these.