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cooling/slip /oil spot

updated sun 8 nov 09

 

Bill Merrill on sat 7 nov 09


Since there has been discussions of glaze cooling , reduction at =3D
diffirent I thought I'd pass alon to you part of a letter I just =3D
received from Val Cushing. In a class he taught on clay and =3D
glazes, etc. I remember him tlling a stoty about a clay from a brick =3D
yard in Sandy Hook, Ny York...
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Part of a letter From Val Cuching to Bill Merrill 11/7/09
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"The story about the "oil spot" glaze was that Charles Harder=3D20
recognized that the Chinese oil spot and the Japanese oil spot was=3D20
actually "just" a straight earthenware slip glaze, like Albany, only=3D20
it produced rust or silver spots in the glossy black Tenmoku. He=3D20
discovered a test made by the NYSTATE geological survey guys ( it was=3D20
once located in the ceramic college )who were testing the clays in=3D20
every part of NYS and firing them at 04, 6 , 9 and 12 to see what=3D20
commercial potential they had. He noticed one that had the Oil Spot=3D20
characteristics ( rust or silver spots on glossy black ) and it was=3D20
from a red clay that the survey guys had taken form an abandoned brick=3D20
making company at Sandy Hook NY. Harder took some grads and the=3D20
school pick up truck and brought back some of that clay. I was a first=3D20
year grad. and we all were assigned to make a Chinese Glaze and make=3D20
pots to correspond to the ones the Chinese put each glaze type on . =3D20
But we all made tea bowls for the oil spot , sandy hook , slip glaze. =3D20
It was planned so that we unstacked all the pieces when the ...." Far=3D20
Eastern Ceramic Society " came to Alfred for their annual convention .=3D20
Harder had planned all this because the Far Eastern Ceramic Society=3D20
was made up primarily of art historians, museums curators , etc. and=3D20
they had considered most of the Chinese glazes to be big secrets ,=3D20
especially the oil spot. When we opened the kilns the group was all=3D20
there in the kiln room and when they saw the oil spot they were amazed=3D20
and applauded and were knocked out by the glaze. Then Harder gave a=3D20
paper to them explaining that the big mysterious oil spot glaze was=3D20
the simplest of all , and was nothing but a particular red clay fired=3D20
to cone 12 , up in oxidation to cone 9, then reduced to cone 12 and=3D20
then fast cooled to freeze in the rust and silver spots. We eventually=3D20
used up all the clay we had and never went back for more and then the=3D20
whole brick plant in Sandy Hook was bull dozed and developed into=3D20
housing units ....... and that was the end of the clay."

Val Cushing 11/7/09

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