Sarah House on wed 30 jan 02
I was looking for some opinions about the article in PMI about kiln
controller programs. With all the talk about slow bisques i really wondered
about the second segment being 360 degrees per hour. I just wondered if my
kiln would be able do it. i've got a Scutt 1227 with middle age elements.
Any thoughts? I'm really thinking hypothetically, I've been reading all the
pros and cons of actually going that fast.
Sarah House
--
www.SKHPottery.com
PO Box 84
Little Switzerland, NC 28749
828-756-1191
Cindy Strnad on wed 30 jan 02
Hi, Sarah.
It doesn't matter if your kiln can fire that fast.
But you can do the second segment of the bisque
faster than the first--you don't have to. If you
have problems (pinholes, probably), that means
your bisque may have been too fast to burn out
organics. It could mean other things, too, but
that's one of the possible culprits. As long as
you're not having trouble, a fast bisque at the
end shouldn't make that much difference. Now, if
you've also included some glazed pots which you
want to grow crystals they missed on their way
down (iron reds that came out brown, for example)
from the last glaze firing, you'll want to slow
things down--maybe give the kiln a very slow rise
for the last 20=BA F or so, or else a controlled
cool.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
cindy@earthen-vessels-pottery.com
http://www.earthen-vessels-pottery.com
Frederich, Tim on thu 31 jan 02
Sarah,
When I suggested this program, the idea was to use a hold in the beginning
to dry the ware completely. After this you can fire rapidly until you come
to quartz inversion. I slow the program down approximately 50 degrees
before quartz inversion which is 1063 degrees F and 50 degrees after. I
think that this gives all of the ware a chance to even out as it passes
through this point.
Your kiln may not be able to go this fast, but some kilns can in this early
stage of the firing. This is the temperature that is built into the cone
fire programs in most controllers. Even Ron and John suggest a fast rate in
the schedule in their new book (page 143). I am of the opinion that this
fast rate in the second segment will not cause any harm under normal
conditions.
Best regards,
Tim
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