SUSAN MASTERMAN on sun 3 aug 97
To those of you who mix your own high-fire white stoneware,
I mixed up an old clay recipe about a year ago. The clay threw very nicely and
what survived looked quite lovely out of the salt and wood firings. The problem
with this particular body is the high percentage of spiral cracking, especially
in a reduction kiln. I have had the clay slaking all this time and am ready to
alter the recipe so that I can hopefully minimize this problem. My question is
this, what should I add to the recipe and in what amounts.
Recipe:
47 goldart
32 ball clay
21 silica (200 mesh)
I think I adjusted the silica when I mixed up the present batch to 18% and added
3% more ball clay.
Any thoughts would be appreciated regarding both ingredients and a way to adjust
for the water content when considering specific amounts to add.
Thanks,
Susan Masterman
Ron Roy on tue 5 aug 97
Do I assume you are firing this to cone 10? You need to have some spar to
prevent cristobalite build up - 10% would be ideal but - this body would be
over fired if you did that. I would recommend a much lower percent of
GoldArt as well - My rule is - never have more than 1/3 of a body with any
one clay - I even think that is playing with fire unless you have evidence
that the clay is relatively stable.
Unfortunatley I don't have a body that I can post - I can advise if you
will supply the kinds of clay you have access to however. You must be
willing to test any suggestions however.
>----------------------------Original message----------------------------
>To those of you who mix your own high-fire white stoneware,
>
>I mixed up an old clay recipe about a year ago. The clay threw very nicely and
>what survived looked quite lovely out of the salt and wood firings. The
>problem
>with this particular body is the high percentage of spiral cracking, especially
>in a reduction kiln. I have had the clay slaking all this time and am ready to
>alter the recipe so that I can hopefully minimize this problem. My question is
>this, what should I add to the recipe and in what amounts.
>
>Recipe:
>47 goldart
>32 ball clay
>21 silica (200 mesh)
>
>I think I adjusted the silica when I mixed up the present batch to 18% and
>added
>3% more ball clay.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
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