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pop outs/ coleman raku clay

updated sat 5 jun 99

 

Bryan Hannis on wed 2 jun 99

Hi

Does anyone know the answer on how to cure pop outs that occur on coleman
raku clay made by Clay Art Centre of Tacoma?? This is the second batch that
I've got from them and is the only clay that I can get in my area that will
with stand the stress of the type of firing that I do. So any ideas or help
would be greatly appreciated.

Bryan Hannis

Ron Roy on fri 4 jun 99

There is no cure for pop outs once they are in the clay - at least not for
unvitrified clay. I can see them once fired to vitrification as an attempt
to seal the calcium off from absorbing moisture but there will still be
some near the surface that will hydrate and pop.

The problem is in your clay suppliers production - they don't sieve their
fire clay through 30 mesh - which is the common way to avoid the problem.
Perhaps you should ask them to do this - a custom batch - perhaps they will
get the message.

Christie now sells a 40 mesh (or is it 50M) grind of their Hawthorn fire
clay - that will probably be OK - has anyone else found other clay with
lime in them?

RR

>----------------------------Original message----------------------------
>Hi
>
>Does anyone know the answer on how to cure pop outs that occur on coleman
>raku clay made by Clay Art Centre of Tacoma?? This is the second batch that
>I've got from them and is the only clay that I can get in my area that will
>with stand the stress of the type of firing that I do. So any ideas or help
>would be greatly appreciated.
>
>Bryan Hannis

Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849

Web page: http://digitalfire.com/education/people/ronroy.htm