John Tilton on sat 2 nov 96
I've just unstacked a kiln with several large round porcelain covered
jars-------16 to 20 pounds each and sitting on ~ 4 inch bases, at least before
the firing. They have slumped horribly. In the process of destroying them I was
able to see that the clay was not " too " thin, between 1/4 and 5/16 inch. The
clay body was a commercial one, Miller 550 and the cone was a hard 10.
Does anyone have suggestions as to how to alter this body to allow these pots to
be made, or can someone suggest another clay body to use for large work?
Does molochite grog leave the clay speckled?
Thank you in advance.
John Tilton
Alachua,FL
PS. I will be exhibiting at the Philadelphia Craft Show next week----Thursday
thru Sunday---Nov 7-10. Please stop by if you are able to attend--space 502.
It's a nice show.
Tony Hansen on mon 4 nov 96
> I've just unstacked a kiln with several large round porcelain jars (15 lbs)
> They have slumped horribly.
I wonder if you are not expecting too much from your porcelain. Translucency
and fired stability are usually mutually exclusive.
Many manufacturers are making non-vitreous whiteware bodies now. These fire to
1-2% porosity but are more stable in the kiln and fire very white (IMCO
Geostone and Plainsman H570 are examples). How about firing to cone 8.
Molochite grog can be contaminated with iron specks. Even if it isn't it leaves
white specks on a grey-white body.
--
Tony Hansen, IMC
134 Upland Dr., Medicine Hat, Alta T1A 3N7 Canada
Phone:403-527-2826 FAX:527-7441 email: thansen@mlc.awinc.com
web: http://digitalfire.com/imc.html
COOPJ@aol.com on wed 6 nov 96
John,
I don't know which body you used but it sounds loke it was fluxed pretty
well.
One additive that can be used to help is about 3-5% Alumina oxide 200-325
mesh.
Try wedging some into your clay (remember moist clay is about 80% dry
material)
If this works Miller will mix you a special batch but will probably require
2000#.
Jim Cooper
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