vince pitelka on sun 17 sep 00
> at 438 centigrade. Another explosion. This time back shelf. First
> time front shelf.
> Any ideas? Only other thing that may be significant is that the second
> shelf was one that survived the
> first firing. They had been outside. It had rained in past 10 days but
> had left them out to dry in sun during recent
> sunny days. My guess is moisture. If so, know what to do.
Fred -
I'd say moisture for sure. You may have seen my post a week or so ago
referring to explosions while re-firing previously glaze-fired wares which
have been in daily household use or have been left out in the weather. The
same thing seems to be happening here. I am not familiar with the structure
of Advancer kiln shelves, but apparently they have a miniscule amount of
porosity. That is actually the worst, regarding potential for explosion.
Water soaks into vitrified clay very slowly, and can only get out very
slowly. If heated quickly, the clay can explode with tremendous force. You
need to put your shelves in a warm kiln for a day or so - soaking at about
200 degrees F. And don't leave them out in the weather any more. Then they
should be OK to use.
Good luck -
- Vince
Vince Pitelka
Home - vpitelka@dekalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
http://www.craftcenter.tntech.edu/
Fred Cook on sun 17 sep 00
Glad to have a place to ask some advice.
Have been using Advancer kiln shelves in wood fired kiln. They have
performed great
over about 10 firings. Today, one exploded early in firing. I stopped
firing. Cleaned up the mess.
restacked the kiln, used another advancer. Started firing again this
evening.
at 438 centigrade. Another explosion. This time back shelf. First
time front shelf.
Any ideas? Only other thing that may be significant is that the second
shelf was one that survived the
first firing. They had been outside. It had rained in past 10 days but
had left them out to dry in sun during recent
sunny days. My guess is moisture. If so, know what to do.
If not, what could it be?
Fred Cook
Nils Lou on mon 18 sep 00
WATER
--now you know what to do...nl
On Sun, 17 Sep 2000, Fred Cook wrote:
> Glad to have a place to ask some advice.
> Have been using Advancer kiln shelves in wood fired kiln. They have
> performed great
> over about 10 firings. Today, one exploded early in firing. I stopped
> firing. Cleaned up the mess.
> restacked the kiln, used another advancer. Started firing again this
> evening.
> at 438 centigrade. Another explosion. This time back shelf. First
> time front shelf.
> Any ideas? Only other thing that may be significant is that the second
> shelf was one that survived the
> first firing. They had been outside. It had rained in past 10 days but
> had left them out to dry in sun during recent
> sunny days. My guess is moisture. If so, know what to do.
> If not, what could it be?
> Fred Cook
>
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Craig Martell on mon 18 sep 00
Hi:
I heard about one other incident of exploding Advancers. These shelves had
been stored outside too and had gotten wet. I think that's the common
point here. You need to keep these shelves out of the weather and dry.
I use Crystars and Advancers in a gas kiln and fire to cone 10R. I've
never had one pop and I've been using some of them for 10 years.
later, Craig Martell in Oregon
Steve Mills on mon 18 sep 00
> My guess is moisture. If so, know what to do.
>
>Fred Cook
>
Fire slower at the beginning. Wet kilns and shelves are an accident
waiting to happen
--
Steve Mills
Bath
UK
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