[Clayart] bisque temps and glaze

David Hendley via Clayart clayart at lists.clayartworld.com
Fri Feb 27 19:30:12 EST 2015

You cannot really bisque at any temperature you want.
My experience is that for small items that my be true, but once you
start firing platters or bowls that are over about 16" diameter
the bisque temperature becomes more critical.
Big bowls that are "soft bisqued" have a much greater chance
of cracking during bisque-fire cool down. This is because the
rim cools faster than the foot (especially true if fired in an
electric kiln only a little bigger in diameter than the bowl
because the area close to the kiln wall cools much faster).

I used to bisque fire "by eye" and not worry about it. When
I started having trouble with large diameter pieces cracking
I put a cone 06 in the kiln setter and that took care of the
problem. I think it is only natural to under-fire if you think you
can fire by atmospheric color only!

David Hendley
david at farmpots.com

----- Original Message ----- 

> there are a few concepts that don't get taught.
> one...you can have any bisque temp you want.
> it is up to you.
> cone 011 will give you very sponge like bisque..glaze
> will suck in fast.
> 06 is really hot, and makes the ware tight.
> takes longer to get the same amount of glaze
> sticking to the pot.
> just simple logic.
> we had soft bisque in japan,  then it was
> critical to knowing how long it was in the bucket.
> we had a sweep second clock.  we timed the
> insertion into the glaze.
> like 6 seconds, inside the same.
> some glazes took 10 seconds.  but, you knew the timing for each
> glaze.
> so.

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