John Rodgers on tue 11 mar 03
With all this discussion about what porcelain is or is not, and whether
it is really porcelain if it is fire at less than cone 10, has raised a
question for me.
I fire to cone 6 a slip casting body that is markets specifically as
"Porcelain". It fits all the descriptions I have ever read about for
porcelain. .. Parian white, translucent where thin, sonorous, fully
vitrifies and requires no glaze to make waterproof.
I also fire a throwing body identified as Cone 6 Grolleg Porcelain. It
vitrifies nicely, and meets all the above criteria but is opaque instead
of translucent where thin. Takes glazes beautifully.
I also fire a throwing body - Cone 5 B-mix, which I sometimes fire to
Cone 6. Either way works, depending on the glazes used. The B-mix is
parian white and very porcelain like in throwing, BUT, it has none of
the other porcelanious qualities. Fires to slightly off white.
The clay mentioned in the first two items is, so far as I am concerned,
true hard paste porcelain. The last one is not.