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"soft-paste" - vs. "hard-paste" porcelains (long)

updated wed 21 jul 99

 

Assumption Abbey on tue 20 jul 99

Dear Readers:

I am seeking a (different) porcelain clay body and currently have
about 4 clay bodies in the test run. I consulted CERAMIC MONTHLY - (June,
July, August 1991) and found a full listing of porcelain clays suitable for
throwing and handbuilding. Soft pastes are nearly glass like and my
question is: What cone or temperature range do you consider a body to be
soft paste porcelain? Or what is the difference between 'soft' and 'hard'
paste porcelains in terms of (cone).

Has anyone tried these from the CM list- Can you recommend one?

David Leach Porcelain Body
(cone 10)

Flanagan Porcelain Bopy
(cone 10, reduction or Oxidation)

Porcelain body
(cone 10, reduciton or Oxidation)

Martin Porcelain Body
(cone 10, reduction or Oxidation)

Griffith Porcelain Body
(cone 8-10)

Utah Porcelain Body
(cone 9-10, RE, or OX)

Ferguson's Porcelain Body
(cone 10-11, RE, or OX)

Porcelain Body NS7
(cone 90

Harry Hall Porcelain Body
(cone 9, RE or OX)

Porcelain body
(cone 6-11 RE, or OX)

Peleg Porcelain Body
cone 6 RE, or OX)

Rothman Porcelain Body
(cone 3, reduction or OX)

Duca Porcelain Body
(cone 05, RE, or OX)

From Ceramic Monthly Technical Staff,- The very best, true porcelain-
like that used at Porsgrund in Norway-is quite nonplastic (unsuitable for
anything but casting).and fires at cone 15-well beyond the range of most
electric kilns (unless yours is fired with Globars or Silicon carbide
elements). There are recipes for good quality porcelain that can be fired
at cone 10 or below, well within the range of most electric kilns, though,
durability, however, is strongly tied to firing temperature/vitreousness.

Translucency can be improved with some of the lower-firing
'soft-paste' recipes; while not true porcelains, they are quite handsome
materials in their own right. Soft pastes are nearly glass because of
thigh flux content.

Can anyone recommend a good porcelain that is elastic, good throwing
qualities, very limited amount of cracking, and with good carving and
translucent qualities?



Llewellyn Kouba
ABBEY POTTERY
http://www.assumptionabbey.com/Pottery.html