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electric kiln mystery - long rr

updated tue 16 apr 02


Maid O'Mud on mon 15 apr 02

I've got a kiln problem I just can't crack. Can anyone help?

I've had the same kiln for about 15 years. It is rated ^10, and was =
fired to ^10 for many years.

I switched to ^6 clay and glazes about 1.5 years ago, and changed all my =
elements just prior to that time. They were all ITC coated by Tuckers. =
The elements fired wonderfully. Until the last 2 firings, the kiln has =
been totally even top to bottom.

In the last 2 firings, the top witness cones went down quite quickly as =
per normal (I've been doing the R&J technique of running up fairly =
quickly, then controlled cooling) but the bottom cones refused to budge. =
The first time, I gave up quite quickly, unloaded and my husband and I =
checked connections, elements etc. Connections are clean and tight. =
Elements are continuous and each passed the paper test easily. (ie =
laying paper in different spots around the elements to make sure they =
catch fire when the element is turned on.) Having checked everything we =
could, we re-loaded (with fresh ware) and tried again.

The bottom switch is attached to 2 hotter wires (done 10 years ago to =
even out the kiln). It fired quite hot. No cone packs were on the =
bottom shelf, but the glaze started to run a bit. The 2nd shelf has the =
bottom kiln pack (cone 5 down, cone 6 barely moved), and the next shelf =
is where the cone sitter goes. They were on the cool side...the kiln =
sitter didn't drop until the bottom cones dropped. The top shelf and a =
half were perfect with cone 6 at 3 o'clock. It took 25 hours and much =
fiddling of switches to get the kiln to this point.

Due to our long association and many firings with this kiln, our packing =
is rather consistant load to load. I can't think of anything we haven't =
checked. Do we need to purchase a meter of some kind to check if a =
certain element is "tired"?

ALSO, RR Saffire blue pitted extremely badly on some of the thinner =
pieces (Tucker mid-cal ^6). Could this be caused by a drawn out firing? =
Can I touch up the bad spots and re-fire these pieces?

Until I figure this out, I'll be using my "baby" kiln. It fires evenly =
(so far) but is only about 3.5 cube and cools way too fast. HELP!

Sam - Maid O'Mud Pottery
Melbourne, Ontario CANADA

"First, the clay told me what to do.
Then, I told the clay what to do.
Now, we co-operate."
sam 1994