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cone 5 vs cone 10 clay bodies

updated wed 16 oct 02


Jon Pacini on tue 15 oct 02

Greetings All---Cat wrote:
I have a question about using a Cone 10 clay body vs. a Cone 5 when
firing Cone 6 glazes.

I'm going to take a leap here and jump in as I have done some testing
with the ^10 version verses the ^5 version of B-mix and actually have some
Data on this. Which should just tickle RR to no end.

The ^10 version of B-mix when fired to ^5 has an absorption rate of
approx. 4.25%. At least in the kilns here in the Lab. If your glazes craze
on this porous of ware, it will leak. I would pressure cook a fired piece of
ware for 6 hrs and see if your glazes craze, even if they come out of the
kiln uncrazed. This is a test that should be done on any functional ware.
Even if the body has 1% absorption. The reason being, the clay and glaze may
not be as compatible as they appear and the pressure cooker will prove it
out. If you don't have a pressure cooker, boil the ware. This isn't as
accurate, but pressure cookers aren't as common in the kitchen as they once
were. And don't forget to check the water often, if it boils off, you'll
botch the test.

Going the other way ---^5 B-mix when fired to ^10 has an absorption rate
of approx. .5%. At this point it's reacting much more like a Porcelain than
a Stoneware. We do have a few customers that go this route, but once again I
would suggest you do extensive testing before you commit to production. As
you should with any clay body.

Jon Pacini
Clay Manager
Laguna Clay Co
Where the Halos will soon be World Champions