[Clayart] glaze pops

[Pfeiffer Fire Arts]

All,


After a number of years of not having a lot of problems with pop's in the glaze it has got so bad as to put us out of business. I have been making small changes in our glaze to reduce the surface tension hoping this would help. It has not and the last firing was the worst of the lot. I am not sure there are 5 pieces that we can sell.
This firing had a slow rise from 1700 to 1900 and then a hour dwell at the top to cone 10 - 11. When slow about 2000 to give things time to heel. If anything the pops are bigger with our new glaze then the old one.

Our first glaze base glaze is:

Epk 			12
Petalite 		14
Wollastonite  	20
Silca             20
Custer         	33
Bentonite 		1

Our most recent attempt is to add a frit:

Epk 			6
Cal Epk		6
Petalite 		15
Wollastonite  	17
Silca             20
Custer         	29
Bentonite 		.5
Ferro 3134		6
Veegum		.5

While the calculated CEO is very close (8.60 and 8.61) to the same for both versions we had some shivering when it was thick on one piece.
Anyone want to guess what to do next.

Dan
PfeifferFirearts.com