Fraser on thu 26 feb 98
Just thought I would add something to the discussion on glaze boiling -
bubbles left in the glaze. When I was firing my pots to cone 6 in an
electric kiln this bubble problem was really bad. The advise I received
was
to slow down the bisque firing. As most of you know this is the advise
that
many experts and texts will give. I did this and yet my pots had just as
many bubbles. I then tried slowing down my glaze firing schedule and still
had no success. The only remedy I found was slowing down the temp drop
from
peak temp. When I 'stepped' the kiln temp down very slowly - say over 50
degrees - there was almost no bubbling.
Going from the theory that bubbles are trapped gases that originate in the
clay body, and that eliminating most or all of these gases in the clay
body
could solve the problem, I refired pots with bubbles. To my surprise there
were even more bubbles than after the previous firing! I have also talked
to several potters who fire very fast - bisque in 8 hours, and fire in
even
less- and have no bubbling problems.
Also since I have been experimenting with my fast fire kiln and firing to
cone 7/8 in 2 hours I have not once had a problem with bubbling.
Please understand - I am not taking issue with anyone here and I certainly
have no alternate theory to offer. I welcome any assistance.
The only cure I found was a slow drop in temp from the peak.
Fraser Forsythe
fraserf@golden.net
www.golden.net/~fraserf
Louis Katz on wed 4 mar 98
Just to drop an 'S" into the pinhole problem. These problems sound like
they originate with sulphur compounds. Firing slower does not
necessarily reduce problems caused by sulphur.
Louis
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