Kat in the Hat on tue 12 mar 02
Gem:
It is interesting that you should say that at cone 6 there was even more
craters. I am assuming that the craters are infact craters, (you can =
see the=20
clay body) or is it possible they are blisters? the glaze is not being =
overfired? Anyhow what I found is first=20
to look at your glaze recipe, is there materials that produce alot of =
gas.=20
For example calcium carbonate has a L.O.I of almost 50%!. If so exchange =
for materials that produce less gas (wollastonite insteed of whitting) =
What kinds of coloring oxides are you using? Manganese can creat big =
problems in that way.
At some point while your glaze is being fired alot of gases are being =
released and sometimes that happens to be at exactly cone 5 or 6 =
(depending on glaze) Try=20
firing to cone 5 with a longer soak. or cone 7. (if you have that type =
of room to move) quick firings with rapid cool down seems to freeze =
bubbles into place not allowing any time for them to heal. Hmmmm the =
only other advice I can add is that your bisque firing may be to quick. =
Most gases release out of your clay body at the higher temperatures, so =
that should be taken slowly to. Well hope this helps you. =20
Kat
kat@digitalfire.com
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