Arnold Howard on sun 30 may 99
Dai Scott described a kiln that fires two cones cooler in the bottom
section. (See end of this email.)
Suggestion:
Mass inside a kiln acts as a heat sync. Some electric kilns fire cooler
on the bottom because the massive brick bottom is a heat sync.
Before replacing elements, try loading lighter ware on the bottom. You
might also try raising the bottom shelf so that instead of being 1"
from the brick bottom, the shelf is perhaps 8". The shelf, too, is a
heat sync. Load more heavily in the center section.
I welcome comments on this idea.
Arnold Howard
Paragon
> Hi, Judy - I have an older Skutt, 23'' dia. 27"
> deep; have had increasingly
> inconsistent firings with it in the last few months,
> and finally did the
> large-cones-in-a-cone-pack thing (prior to this, I
> have been relying only on
> the kiln sitter with a bar cone to shut it off at
> ^6). To my amazement, I
> discovered that the bottom shelf (which is up on 1"
> posts) fired to ^5
> (barely), the middle shelf fired to ^7, and the top
> one to ^6. I can't
> believe there could be this much difference!
> We are going to do a complete change of elements
> (it's past time) and then
> I'll test it again. The kiln was packed quite well,
> with all full
> shelves---I wonder if there would have been less
> difference if I'd had
> staggered half-shelves in there? Anyway, at this
> rate, it's no wonder I
> can't get consistent glaze results in this kiln!
> Now I'm going to test my
> other one---hope it's better.
> Incidentally, my routine is all three switches on
> low for 1-2 hrs, all on
> medium for 1 hour, all on high and shut lid. The
> top peephole is always
> open. Any comments, anyone?
> Dai Scott - mystified in Kelowna, B.C.
>
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Linda Blossom on tue 1 jun 99
When I stack with the most narrow pieces in the bottom and getting
progressively taller as I go up I get even heat. It is the opposite of what
I find in my gas kiln. In gas, open areas draw heat (in my experience)
while in electric kilns open areas hold less heat. Since the top of the
electric tends to be hot, by having it as open as possible, I am able to
cool it down while the greater mass in the bottom holds onto the heat there
where it is usually cooler. But that is in my kilns and I realize that they
all seem to fire their own ways.
Linda Blossom
2366 Slaterville Rd
Ithaca, NY 14850
607-539-7912
blossom@twcny.rr.com
-----Original Message-----
From: Arnold Howard
To: CLAYART@LSV.UKY.EDU
Date: Sunday, May 30, 1999 11:39 AM
Subject: Uneven Heat Distribution
----------------------------Original message----------------------------
Dai Scott described a kiln that fires two cones cooler in the bottom
section. (See end of this email.)
Suggestion:
Mass inside a kiln acts as a heat sync. Some electric kilns fire cooler
on the bottom because the massive brick bottom is a heat sync.
Before replacing elements, try loading lighter ware on the bottom. You
might also try raising the bottom shelf so that instead of being 1"
from the brick bottom, the shelf is perhaps 8". The shelf, too, is a
heat sync. Load more heavily in the center section.
I welcome comments on this idea.
Arnold Howard
Paragon
> Hi, Judy - I have an older Skutt, 23'' dia. 27"
> deep; have had increasingly
> inconsistent firings with it in the last few months,
> and finally did the
> large-cones-in-a-cone-pack thing (prior to this, I
> have been relying only on
> the kiln sitter with a bar cone to shut it off at
> ^6). To my amazement, I
> discovered that the bottom shelf (which is up on 1"
> posts) fired to ^5
> (barely), the middle shelf fired to ^7, and the top
> one to ^6. I can't
> believe there could be this much difference!
> We are going to do a complete change of elements
> (it's past time) and then
> I'll test it again. The kiln was packed quite well,
> with all full
> shelves---I wonder if there would have been less
> difference if I'd had
> staggered half-shelves in there? Anyway, at this
> rate, it's no wonder I
> can't get consistent glaze results in this kiln!
> Now I'm going to test my
> other one---hope it's better.
> Incidentally, my routine is all three switches on
> low for 1-2 hrs, all on
> medium for 1 hour, all on high and shut lid. The
> top peephole is always
> open. Any comments, anyone?
> Dai Scott - mystified in Kelowna, B.C.
>
_________________________________________________________
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Get your free @yahoo.com address at http://mail.yahoo.com
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