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firing cone 6 glaze on cone 8 clay

updated tue 25 apr 00


The Wrights on sun 23 apr 00


I've been away for a while, but now I'm back. I have the opportunity to do some
work at a near by studio, after not touching it for a year and a half (IT WAS
AGONY!!!!). It was so depressing to read about all of you doing what I loved to
and I couldn't do it, so I stopped my subscription for a while.

I have a collection of pieces that were made from cone 8 stoneware, but the stud
only fires cone 6 kilns and they only provide cone 6 glazes. I am new there so
don't want to push my luck asking for any special favors, so I was wondering if
could fire my cone 8 clay with a good coating of cone 6 glaze (food safe) and i
still be able to handle food and liquids. If not, I suppose they can all become
vases, "stuff" holders and "spider houses". (The latter is what I lovingly call
sculptural forms.)

I am sure that someone will be able to help me with this. I did check the archi
before I wrote and I didn't find any past discussion on this.

Thank you in advance for your help.


Cindy Strnad on mon 24 apr 00


You can do it, but it may not be vitrified. Fire a bar of your ^8 clay to
^6. Weigh it. Boil it for 30 minutes or so, shake it dry, and weigh it
again. Did it take on much water? (someone else will need to tell you how
much is too much) If it takes on too much water, it is not sufficiently
vitrified at ^6. The glaze will seal it if it's a good glaze with a good
fit, but the foot will be able to take on water and may mildew in a humid

Clay is not all that expensive. I know it's a pain, but maybe you would
consider buying some new clay. Might make things easier all around. You're
doing new glazes anyhow, so you might as well take the whole plunge at once.

Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730