pam easley on sat 29 may 99
The color of the clay does not indicate the cone at which it matures.
You can safely bisque at your regular temp, 03,04 or whatever, and then
experiment from there. You may be able to tell by the sound of the glaze
fired piece, if it gives you a ping sound (probably at least close to
maturity) or thunks (still underfired) when you hit it with your
fingernail or a spoon. Be sure to put a plate or bowl under it when you
test glaze your first piece in case it melts when you get it up to cone
6 or so!
Good luck!
Pam, near Seattle
Fredrick Paget on sun 30 may 99
I have been digging local clay all over the county and have a system to
tell the maturing temperature of a sample.
I make a small test bar out of the test clay the same size as an Orton bar
cone and put it in the kiln sitter. Then I make a couple of cone packs with
a lot of cones in a series that go both sides of the possible maturing
temperature and put them on the shelf in front of the kiln sitter. That way
I know what cone the kiln was at when the kiln sitter shut it off. Add a
couple of test pieces on catch plates of hi fire clay if you want. I set
the computer to a higher cone than I think the clay will take and fire it
off. When that bar bends the clay is a cone above maturing temperature. The
kiln sitter shuts down and your cone pack tells you the cone reached.
Fred Paget
>----------------------------Original message----------------------------
>The color of the clay does not indicate the cone at which it matures.
>You can safely bisque at your regular temp, 03,04 or whatever, and then
>experiment from there. You may be able to tell by the sound of the glaze
>fired piece, if it gives you a ping sound (probably at least close to
>maturity) or thunks (still underfired) when you hit it with your
>fingernail or a spoon. Be sure to put a plate or bowl under it when you
>test glaze your first piece in case it melts when you get it up to cone
>6 or so!
>Good luck!
>Pam, near Seattle
From Fred Paget, Marin County, California, USA
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