Pam Cresswell on mon 10 jan 05
Humph. A month or so ago, I mixed a batch clear ^04 glaze, from a book.
Another potter and I used it immediately after mixing,
Fired the pieces, and all was well. Last week, I wanted to use the glaze
again, but it had gotten so thick, it was unusable. It looked like it had
coagulated like cold gravy!
I sieved it and added water to get it back to cream thickness. It took a lot
of water.
Then the same other potter and I used it again. In the first firing, with
just my pots, they shivered so badly, I had to use tongs to get them out if
the kiln, and put them strait into the trash.
The pots shattered in a spiral fashion, following the flow of the wheel
throwing. There were clear glass shards all over the kiln shelf that had to
be vacuumed away. I thought it was from a different glaze that that was also
on my pots, since the clear had worked fine before. So I fired my friend's
pots yesterday, and when I opened the kiln today, it was the same thing,
shiver shiver. His were slab built so there was no spiral shattering, but
through out the day we saw the pots shed glass and have an occasional dunt.
I popped the recipe into Glaze Master to look at it's expansion coefficient,
and compare it to other ^04 glazes. It is 69.48, but silly me, I have this
number, but I have no idea if that is a high or low number.
I also do not know why it worked fine before, but after slaking for a few
weeks it is so different!
Here is the recipe:
Odyssey ^04 clear base
Laguna borate 61.5
EPK 24.6
Flint 12.3
Lithium Carb 1.6
Pam
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