I have a problem with one new glaze I want to use and I could use some advice on how to fix this problem. I bisquefired at 800, than wiped the plate, than poured the glaze in and emptied the plate right away. Looked perfectly even. I've let it dry, fired it at 1160 with a soak of 30 minutes. The maximum temperature of the glaze is 1170. When I got the plates out of the kiln, all of them had round empty circles with something in the middle that seem to be a grain of overfired glaze. Why is this happening? What am I missing?
I do not think it is crawling because I've diluted the glaze and the same thing happened. I've also used another type of clay and the result was the same. The glaze was sieved when I've mixed it water. It is a commercial glaze, I do not understand glaze chemistry although I wish I do.
Please let me know if someting similar happened to you and how did you solve the problem.