Susan Dickson-Smith on tue 20 jul 04
For the last 6 months or so, I've had increasing trouble with bloating in my
Miller 65 (cone 6 white stoneware). I bisque to 06. I've been wondering if
that's too low, since I seem to be having some other troubles with body
faults (s-cracking appearing in glaze firing even on thin pots, etc). What
puzzles me is-- my Miller 50, cone 6 with flecks of iron, never ever bloats.
I read the recent bloating in stoneware thread--it raised lots of good
questions and made me wonder more about bisquing too low. 65 is listed by
one of my suppliers as a ^6-8 clay, whereas 50 is ^4-6. I've bisqued them
together (slowly, but heavily stacked) up to this point. Should I be
bisquing them separately and taking the 65 to a higher temp? Or are there
other things that I should try before resorting to segregation?
I'm a little hesitant to start bisquing everything to ^05 or above, partly
because I have a ton of ^06 cones and partly because I don't want to create
new problems (especially since the 50 is behaving). Any thoughts would be
appreciated.
william schran on wed 21 jul 04
Susan wrote:>For the last 6 months or so, I've had increasing trouble
with bloating in my
Miller 65 (cone 6 white stoneware). I bisque to 06. I've been wondering if
that's too low, since I seem to be having some other troubles with body
faults<
I wouldn't think increasing your bisque temp from cone 06 to cone 05
would make much difference.
Soaking for 20-30 minutes at cone 06 would be better.
I don't think the bisque temp would be the cause of bloating, if what
you're seeing is true bloating. If you have bloating the clay body is
being overfired or there may be some materials in the body causing
problems.
Be sure to use witness cones for your glaze firing to be certain
you're not overfiring and contact the clay manufacturer with the lot
number giving you problems to see if they've heard from others with
similar issues.
Bill
| |
|
