My ancient Kerr 666 kiln recently had to have the pyrometer
replaced. The former owner had melted the front of it, making it
almost unreadable at anything hotter than 1000F. Ever since the new
pyrometer was installed by a local jewelry supply shop, it has not
provided consistent readings. I tried to fire some regular PMC, which
has to be held at 1650F for 2 hours. Before the pyrometer ever reached
1500F, the PMC had melted into little balls. Yesterday we had to cast
some sterling silver, and at the same setting that took the kiln to
the point that ruined the PMC, it never got hot enough to burn off
the ash from the investment. I turned it up to complete the burnout,
then turned it back down until the flasks were not glowing. When we
cast, every flask came out with heavy firescale on the silver.
Obviously it was still too hot.
My main question is, does this sound like the kiln itself needs
repair, or is this just a mis-calibrated pyrometer?
And if it needs repair, would it be better to just replace the poor
old thing? If so, what company makes a good affordable small (4-6
flask) burnout kiln? (I also have a large 220volt kiln, but no 220
power line at the moment).
Feathered Gems Jewelry