Mary Allen on wed 20 oct 04
Is it possible to refire already glazed stoneware that has been fired to =
Cone 6? If so, how would this best be accomplished? =20
We use an electric kiln at our local rec center and usually only use low =
fire, and are just now experimenting with stoneware and porcelain. We =
are trying to raise money to buy a computerized kiln that can fire to =
higher temperatures and doesn't allow for as much human error. =20
Thank you in advance. I apologize for such a simple question. I learn =
a lot reading all your expertise!!
Hugs and Prayers,
Mary in OH
Cynthia Bracker on thu 21 oct 04
You might also check the archives. This subject came up about 2 months
ago and there were a LOT of suggestions! IMHO, if you're set on
refiring, you will want to get some APT-II to add to the glaze. It will
help the glaze adhere to the already glazed piece.
Good luck!
Cindy Bracker
Mary Allen wrote:
>Is it possible to refire already glazed stoneware that has been fired to Cone 6? If so, how would this best be accomplished?
>
>
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Snail Scott on fri 22 oct 04
At 08:05 PM 10/20/2004 -0400, you wrote:
>Is it possible to refire already glazed stoneware that has been fired to
Cone 6?
Absolutely! I do it often. My own work is time-
consuming sculpture, so it's worth it to refire if
that will result in a better surface. What a waste
it would to lose a month's hard work to a substandard
surface, if refiring will cure it.
>...If so, how would this best be accomplished?
When refiring previously high-fired
clay, especially if it's been glazed in the
previous firing, let it dry very well - any
vitrified (or even semi-vitrified) coating can
trap moisture underneath which will have
difficulty escaping (like the condensation in
a cracked headlight). This is even more important
if the clay is still slightly absorbent, if the
work is reglazed before the second firing, or if
it is allowed to get wet otherwise. A badly-fitted
glaze with crazing creates more risk, but a dry-
footed piece can still absorb moisture unless the
clay is fully vitified. Quartz inversion is not
a big issue for ^6 ware, so general firing speed
need not be varied, except to make sure that it
candles long enough. Bisque is actually more
forgiving of being fired while damp than semi-
vitrified glazed clay. The clay may be stronger,
but the moisture has a harder time escaping, thus
the need for a little extra candling time. If
your clay is really vitrified, all this will be
irrelevant, but if the firings are likely to be
variable, play it safe.
It's really no big deal; just go ahead and fire.
The 'moisture-under-glaze' issue is not a common
source of trouble; merely one to be aware of.
Note that matte glazes will tend to get even more
so, and some gloss glazes may tend to lose their
gloss slightly ('devitrification').
-Snail Scott
-Snail Scott
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