Arnold Howard on wed 3 nov 04
A few days ago Logan mentioned that a kiln melted down because the Kiln
Sitter didn't shut off. I can imagine how distressing that must be, so I am
submitting Kiln Sitter pointers that will help prevent melt downs. These are
very basic, but sometimes it is easy to forget the basics. I'll also add
some Kiln Sitter maintenance tips in a separate post.
1) Warn others not to touch your kiln while it is firing. Bumping the Kiln
Sitter release claw can move the guide plate out of alignment, preventing
the actuating rod from dropping. This will over-fire the kiln. (The
actuating rod rests on top of the small cone in the Kiln Sitter. The release
claw is on the other end of that rod. The guide plate adjusts the release
claw from side to side and is held in place with two screws.)
2) Place only stable ware inside the kiln near the Kiln Sitter tube. If
someone bumps the kiln, an unstable stilted piece could fall against the
actuating rod, causing an over-fire.
3) Keep ceramic shelves at least one inch above or below the Kiln Sitter
tube. If jarred, a shelf that is even with the tube could press against the
actuating rod, causing an over-fire.
4) A piece of exploding greenware could lodge against the actuating rod,
causing an overfire. Make sure greenware is bone dry before firing.
5) Keep a record of your firings so that you will know how long a firing
should take. Then set the Limit Timer on the Kiln Sitter for 30 minutes to
an hour longer than the expected firing. (If your Kiln Sitter does not have
a knob, it doesn't have the Limit Timer.)
6) Learn to estimate the temperature inside the kiln by the color of light
around the lid. This will help you to know at a glance if the kiln is
over-firing.
7) Place witness cones on the shelf and position them so you can see them
through a peephole. If you ever suspect that the kiln is firing too long,
check the cones.
8) Never leave the Kiln Sitter unattended during firing. Though it shuts off
the kiln automatically, it still needs the operator's attention.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
arnoldhoward@att.net / www.paragonweb.com
Laurie Kneppel on wed 3 nov 04
On Nov 3, 2004, at 2:09 PM, Arnold Howard wrote:
>
> 4) A piece of exploding greenware could lodge against the actuating
> rod,
> causing an overfire. Make sure greenware is bone dry before firing.
This was a great primer on kiln sitters!
I had to note, though, that I had sort of the opposite thing happen
once.
A piece of exploding greenware hit the kiln sitter, dislodged the cone
and shut off the kiln.
There was good and bad from this event.
The good was I was able to salvage the sculpture I had worked weeks on,
re-wet it and rebuild it.
The bad was that I had to learn this lesson the hard way when I "should
have known better"! That the outside may be dry...
And I had mucho cleaning of clay dust, chips and shrapnel to do before
I could fire the kiln again.
Thankfully the only thing that was damaged was my pride!
Of course I nearly had a heart attack when I dared to open the kiln to
see why it mysteriously shut off so early!
Another lesson learned - don't start a firing when you have company
visiting and can't watch your manually fired kiln closely!
Laurie
Sacramento, CA
http://rockyraku.com
Potters Council, charter member
Sacramento Potters Group, member
Ron Roy on fri 5 nov 04
Good tips Arnold - just a bit more from me.
I had the experience once - explosing ware in a bisque firing - a piece of
clay was blow in under the rod - and preventing the rod from dropping.
One of the problems with sitters is no thermocouple - so judging where
you're at is not easy - they are also handy for soaking and slow cooling.
I think thermocuples, pyrometers and cones are basic requirments when
firing any kiln.
RR
>4) A piece of exploding greenware could lodge against the actuating rod,
>causing an overfire. Make sure greenware is bone dry before firing.
>
>
>
>5) Keep a record of your firings so that you will know how long a firing
>should take. Then set the Limit Timer on the Kiln Sitter for 30 minutes to
>an hour longer than the expected firing. (If your Kiln Sitter does not have
>a knob, it doesn't have the Limit Timer.)
>
>
>
>6) Learn to estimate the temperature inside the kiln by the color of light
>around the lid. This will help you to know at a glance if the kiln is
>over-firing.
>
>
>
>7) Place witness cones on the shelf and position them so you can see them
>through a peephole. If you ever suspect that the kiln is firing too long,
>check the cones.
>
>
>
>8) Never leave the Kiln Sitter unattended during firing. Though it shuts off
>the kiln automatically, it still needs the operator's attention.
>
>
>
>Sincerely,
>
>
>
>Arnold Howard
>
>Paragon Industries, L.P., Mesquite, Texas USA
>
>arnoldhoward@att.net / www.paragonweb.com
>
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Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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