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of cracking pots, and crackpot theories

updated tue 19 jan 10

 

lili krakowski on mon 18 jan 10


Anne Elisabeth Maurland (I cannot resist spelling out the beauty of that =
=3D
name)writes:

"Do you think it makes a difference, according to your theory, that I =3D
glaze the insides first (of the pots that are not plates), wait a few =3D
hours, and then glaze the outsides? That's how I do it."

Yes, and no. I do not think it makes any real difference except that, =3D
as I visualize it, the coating on the inside will drag any solubles into =
=3D
the potwall--which then dries, and maybe, just maybe when the outside it =
=3D
glazed the dryness of the walls allows the outside glaze to drag more =3D
solubles into the pot than if both sides were wet at once. NO idea. =3D
BUT things should not depend on such small "ifs" and "maybes"

To my great comfort Vince tells that " Shinos often go on quite =3D
thick...
soda ash carried into the claybody during
glazing...migrates to the outside of the pot during drying...
any residual soda ash left in the claybody can cause it
to over-vitrify and shrink more than normal, while the shino liner glaze
ends up containing very little soda ash, and thus will be slightly
underfired, shrinking less than normal. The effect is enough to cause
dunting during cooling or later on during use."

In other words the effect of Migrating Solubles is recognized.

As to the testing of a reliable old plate by the freezing/ scalding =3D
method, I really am not convinced of the efficacy of these shock =3D
treatments in the long run. In my limited experience--and, oy, is it =3D
limited--pots that fail do so over time. I have a theory about that =3D
too--doesn't she always?-- basically related to something called the =3D
Griffith Flaw Theory which Fraser discusses (briefly) in "Ceramic =3D
Faults". This is p85 of the book...He also speaks of failure of ceramic =3D
articles because "they cannot withstand over a longer period
of time a load they can safely withstand over a short period."

We have never discussed the GFT and as far as I know only Fraser =3D
does...Duh.

About glaze families...later




Lili Krakowski
Be of good courage