Cindy Strnad on mon 19 jun 00
Bic,
I doubt it's your kiln, since most of the pieces on each shelf were fine.
Sounds like a strange situation. Are you sure your glaze was well mixed?
Cindy Strnad
earthenv@gwtc.net
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
Beth Hamilton on mon 19 jun 00
I have a problem that I would like some feedback on. I have a paragon
Tru-fire (computer) kiln. I have fired it many times since it's acquisition
with no problems. This last glaze firing was to a cone 6 and had ware in it
with Virginia Cartwright's black, one out of Don Davis' book (Ruth's green),
etc. all tested and used glazes. The problem, several mugs on each shelf
(three) were underfired, even though the top and inside of one went to
gloss, the lower portion was rough, underfired - same glaze just half fired,
half not. There was no particular section for these pieces, and five total
pieces in this shape. I am presuming I can refire them to six and possibly
they will even out, but I need to know why. These pieces are mundane
anyway, but when I put something in with a little more work to them, I would
like to know that it is going to work. Would you suggest kiln problems,
perhaps only having a 12 hour turn-around on using the kiln, or that one of
the plugs fell out. Only differences I can find between this and any other
firing. Actually, I've had one of the plugs fall out before with no problem
also. Flash thought, I closed the lid in the dark and the post I used to
lift up the handle was over the hole in the top this morning. Could that
have caused a mis-reading by the pyrometer and basically they entire bunch
is underfired, but the obvious ones either more sensitive or more
underfired? Suggestions? Bic
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amy parker on tue 20 jun 00
Beth Hamilton says:
>The problem, several mugs on each shelf
>(three) were underfired, even though the top and inside of one went to
>gloss, the lower portion was rough, underfired - same glaze just half fired,
>half not. There was no particular section for these pieces, and five total
>pieces in this shape.
After firing my Olympic kiln with sitter 52 times, I had a similiar problem.
I use cone packs on each shelf (usually) and looking at them, I found that
maybe I had only reached about cone 5.5. I suspect that the thinner parts of
your mugs, the tops, reached maturity, and the bottoms did not. My problem
was that the thermocouple was worn out and not accurately sending the temp
to the controller. Take a close look at your themocoople and see if it
looks thinner than you remember it, and if flakes of it are in the bottom of
your kiln. About $40 and an hour on my part restored my kiln to perfection.
I refired the pieces and all went well.
Amy
amy parker Lithonia, GA
amyp@sd-software.com
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