Pam Cresswell on tue 22 nov 05
My most recent firing went oddly. I have a small dinosaur kiln (paragon
a-88) that I dearly love, and I fire it almost every weekend, with pretty
good result. This last firing, I was including a tall goblet that a friend
made, I think it is about 10 inches high. I also had a pretty large bowl of
mine that had to be fired. I put the big bowl on the bottom shelf, then the
goblet on the next shelf. Since I had mugs and tea bowls and rice bowls, I
used a combination of half shelves and broken shelves, and sort of made
scaffolding all around the goblet. The goblet was basically in a cavity from
its base to the top of the kiln. The rest of the space was packed pretty
full, if oddly. As usual I put the thermocouple through the bottom peep, and
a cone pack opposite the top peep. It is such a small kiln, and I have fired
it so many times, I do not usually bother to put a cone pack elsewhere,
because the variation in temp is small from top to bottom. As per my usual
habit, I warmed up the kiln overnight, then turned it up early the next
morning. I keep track of the temperature rise via an inexpensive pyrometer.
It is, just like the Axner catalog stated, not accurate, but consistent.
When it reads 1170 C or so, ^6 is usually falling. That is almost always the
case. This kiln is also very predictable time wise, if I turn the knobs to
"High" at 7:30 am, ^6 is doing a head stand about 1:30 pm. Well, this
firing, when the pyro got to 1145 or so, the kiln seemed to stall. It barely
rose at all for 2 hours, and never reached my usual milestone of 1170. About
2 hours behind schedule, 3PM, cone six finally touched his head to the
floor. It was about an hour from when it first stated dropping, till it was
done, and normally it is 15-20 minutes. The pyro read 1155. I wrote off the
odd readings, and slow firing as being due to the odd packing of the kiln. I
fire by the cones, not the pyro anyway.
So, yesterday when I opened the kiln, it was a real mixed bag. The bowl in
the bottom was good, and the mugs and rice bowls were good, but the tea
bowls and the goblet had blistered. The tea bowls were in the center of the
kiln, and had a commercial clear that is usually very forgiving. The goblet
was glazed in Little Alex's Porter, which has always been the best behaved
glaze in my pallet. Did the part of the kiln around the goblet not get hot
enough because of the odd way the kiln was packed?
I will refire it to see if I can smooth out those blisters, but I
will have the same issue of it being tall and thin without any other tall
thin things to go with it. Maybe I should put a half size hard brick ( did I
hear them called soaps?) next to it this time? Any ideas?
Pam
In sunny KC, where I stayed in bed till noon today, and did not go to the
guild, let someone else do bisque, I am tired
Arnold Howard on tue 22 nov 05
Pam, I think one of your elements failed near the end of the firing.
Paragon's website contains diagnostics information on the A-88B:
http://www.paragonweb.com/catalog.cfm?type=manuals
Select "Ohmmeter Instructions for Testing A-Series Kilns" from the list of
manuals.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
----- Original Message -----
From: "Pam Cresswell"
> My most recent firing went oddly. I have a small dinosaur kiln (paragon
> a-88) that I dearly love, and I fire it almost every weekend, with pretty
> good result.
This kiln is also very predictable time wise, if I turn the knobs to
> "High" at 7:30 am, ^6 is doing a head stand about 1:30 pm. Well, this
> firing, when the pyro got to 1145 or so, the kiln seemed to stall. It
> barely
> rose at all for 2 hours, and never reached my usual milestone of 1170.
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