Craig Martell on mon 21 mar 05
Dan was wondering:
> Has anyone had any reason to bisque a glaze after firing it to a high fire?
Hello Dan:
Yes. The reason that I did this was that I was wondering what the hell
would happen.
I've refired shinos and tenmokus to cone 03 which is basically about 1988
F. If I go up fast the end point might be as much as 2010F. I watch the
senior cone and when it's down, I'm done unless I want to extend the time
and heat for max crystals.
The reoxidation of iron glazes makes for some very nice colors. Warmer
stuff mostly. Sometimes the tenmokus produce an acid yellow that makes me
grit my teeth but that's only if they are applied very thick. Thinner, you
will see warmer reds.
Crystals take time to form and it's an ongoing process. When I refire
celadons with a little magnesia in the glaze they really start to make nice
microcrystals. Crystals are an "ordered" phenomena and you have to hold
the temp around 2000 F for awhile so that the silicates and other ions can
reorder and form crystals. More time, more crystals. It's interesting to
experiment with this stuff.
regards, Craig Martell in Hopewell, Oregon
Pfeiffer, Dan R (Dan) on mon 21 mar 05
Has anyone had any reason to bisque a glaze after firing it to a high fire?
One of the advantages to not knowing what you are doing is that you can do
odd things and learn from it. Thinking that a ^5 heat would help smooth the
edges of drip fixes we put a oil spot in the next bisque firing. This did
not help with the bottom but did great things for the glaze! In quite a
number of places what was brown went to yellow and in general the glaze
looks much more interesting. My guess is that it works much like a slow
cooling, helps form glaze crystals. As our ^ 10 firing often end too late at
night to want to start a fire down cooling cycle, I was thinking maybe this
would be one more way to get a similar effect.
comments?
Dan & Laurel in Elkmont Al
Cindy in SD on mon 21 mar 05
Dear Dan,
I have a number of ^6 glazes that look very different after a re-firing
to bisque. Some glossy glazes which show no effects from a quite slow
cool down nevertheless respond with lovely microcrystals to a re-bisquing.
Have fun experimenting,
Cindy in SD
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