Mary White on tue 12 nov 02
Sorry, I searched the archives but most of the postings on this topic
seem to be about electric firing. Yesterday I did a glaze firing in
my 7 cu. ft. gas kiln for the first time. I had 3 cone packs, each
with a cone 9, 10, and 11: on the top shelf nothing bent, not at all;
in the middle all three were totally melted; on the bottom all three
were bent, cone 9 to the floor, the other two about the same, not
quite down to 90 degrees.
I had no shelf over the top layer of ware. Would putting another
shelf there help? My pyrometer was in the middle. I continued firing
after it reached 2380 F because the top cones weren't doing anything
but as a result the middle overfired.
Any suggestions?
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mary
on the wet west coast of British Columbia
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Dannon Rhudy on tue 12 nov 02
Mary said:
..........did a glaze firing in
> my 7 cu. ft. gas kiln for the first time.
My pyrometer was in the middle. I continued firing
> after it reached 2380 F because the top cones weren't doing anything
> but as a result the middle overfired........
You don't describe your kiln except to say that it is 7 cf. I assume
it is an updraft, but in any case: small kilns will tend to fire
unevenly unless fired slowly in the early part. Because the
compartment is so small, the part nearest the burners tends
to get hot fast and build heat relentlessly.
So, I suggest: make sure your shelves are staggered, so
that the flame and heat can get to all levels in the kiln. Try
to keep the early part of the firing slow, so that heat will
build evenly through the kiln. Keep your stack fairly loose
too, for the same reasons. Just take your time, and expect
to deal with a learning curve that suits both you and your
kiln. Since this was your first firing in the kiln, you have
much to learn. KEEP A LOG BOOK. Note things such
as when the kiln was started, weather (wind, rain, clear, whatever),
what times and how often you increased (or decreased)
the heat/turned the burner(s) up, etc. After a few firings
you will begin to note a pattern that works for your kiln
and situation.
Practice. And remember to listen to the kiln, too, and
note how it smells. These are all helpful hints about
what is going on inside. It may take a while, but you'll
get it sorted out.
regards
Dannon Rhudy
Mary White on tue 12 nov 02
Thanks, Dannon, I know I have a lot to learn. I used a couple of
octagonal shelves that came very close to the sides, only 1/2"-3/4"
away and I used them for the top two shelves of four. One got
slightly warped. I think this was my first mistake, they were holding
the heat in the middle. I won't use them in that kiln again. The
round shelves I bought with the kiln are much smaller but allow more
circulation.
I kept a pretty good record of what I did but it was very windy and I
didn't note that. I'll write it in.
After the strong wax-burning stage I didn't particularly notice how
it smelled! I will in future.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mary
on the wet west coast of British Columbia
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>You don't describe your kiln except to say that it is 7 cf. I assume
>it is an updraft, but in any case: small kilns will tend to fire
>unevenly unless fired slowly in the early part. Because the
>compartment is so small, the part nearest the burners tends
>to get hot fast and build heat relentlessly.
>
>So, I suggest: make sure your shelves are staggered, so
>that the flame and heat can get to all levels in the kiln. Try
>to keep the early part of the firing slow, so that heat will
>build evenly through the kiln. Keep your stack fairly loose
>too, for the same reasons. Just take your time, and expect
>to deal with a learning curve that suits both you and your
>kiln. Since this was your first firing in the kiln, you have
>much to learn. KEEP A LOG BOOK. Note things such
>as when the kiln was started, weather (wind, rain, clear, whatever),
>what times and how often you increased (or decreased)
>the heat/turned the burner(s) up, etc. After a few firings
>you will begin to note a pattern that works for your kiln
>and situation.
>
>Practice. And remember to listen to the kiln, too, and
>note how it smells. These are all helpful hints about
>what is going on inside. It may take a while, but you'll
>get it sorted out.
>
>regards
>
>Dannon Rhudy
>
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