William Brouillard on mon 31 aug 98
Date: Sat, 29 Aug 1998 08:43:08 EDT
From: James Norton
Subject: kiln heat distribution
----------------------------Original message----------------------------
I have a new Olympic kiln, 16 inch, two tier, cone 10, with a Dawson
kiln sitter. I glaze fire to cone 6 and use the kiln sitter to shut off
the current. (I know that this is not recommended.) The cone 6 in the
sitter deforms exactly as it should. In order to evaluate the heat
distribution in the kiln, I placed two cone plaques, using cones 4,5,
and 6, one in the MIDDLE of the lowest shelf, and one in the MIDDLE of
the upper shelf. While the cone 6 in the sitter was perfect, the two
cone plaques showed about cone 4. I glaze fire in about 15 hours,
advancing the heat stepwise. This two cone spread seems excessive to
me. Can anyone suggest how this can be minimized?
Jim Norton
jlnorton@execpc.com
James,
For your next firing place cone packs at the top, middle and bottom
of the kiln. The cone in the sitter will not react the same way to heat
as the cones at the top and bottom of your previous firing. The cone is
in a different position, (horizontal not vertical), and is under
pressure from the rod above it. Some types of cones are better for
placement in the sitter and you might want to try the square bars or the
triangular bar shapes. They may come closer to the cones in the cone-pak.
Try another firing with regular cone-paks at all three levels.
Your kiln may be firing evenly. The best indicator would be the fired
appearance of the glazes. If they look the same from top to bottom
the kiln should be close to even, top to bottom. My experience with
kiln sitters is that they are a safty device and not a good measure of
heat. They are simple mechanical devices and subject to many variables.
They can be adjusted by changing the height of the tab but they are for
back-up and emergency use. Fire by a visual cone or a group of visual
cones.
BB
--
william brouillard
1011 literary road
cleveland,oh.44113
ch151@cleveland.freenet.edu
Wagtime on wed 1 aug 01
Thankyou for the responses to my "Mentor" question. As a result, I am now
tempted to try firing at cone 10 electric. I understand this is the top
temperature of my kiln and wonder if this is wise. TIA Rita
Michele D'Amico on fri 5 nov 04
I have a small skutt kiln. I fire to cone 6 or 7 depending on the glaze
I'm using. I don't have a vent but I leave the kiln propped open and the
plugs out until about 1100 F. Lately when I fire on medium speed with a
short soak I'm finding my glazes are getting a 'muddy' look. Some are
glazes from MC6. My varigated slate blue which was a lovely blue is now a
cloudy gray. Floating blue is muddy gray. Last night I fired using a
friend's glaze that has been a bright lime green (like fiesta ware) in my
kiln in the past and it turned an ugly bilious mud color. Any ideas about
what's going wrong?
Michele D'Amico
damicom@cruzio.com
Arnold Howard on fri 5 nov 04
Michele, are you using witness cones on the shelf?
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
arnoldhoward@att.net / www.paragonweb.com
From: "Michele D'Amico"
>I have a small skutt kiln. I fire to cone 6 or 7 depending on the glaze
> I'm using. I don't have a vent but I leave the kiln propped open and the
> plugs out until about 1100 F. Lately when I fire on medium speed with a
> short soak I'm finding my glazes are getting a 'muddy' look. Some are
> glazes from MC6. My varigated slate blue which was a lovely blue is now a
> cloudy gray. Floating blue is muddy gray. Last night I fired using a
> friend's glaze that has been a bright lime green (like fiesta ware) in my
> kiln in the past and it turned an ugly bilious mud color. Any ideas about
> what's going wrong?
> Michele D'Amico
John Rodgers on fri 5 nov 04
Michael,
I use Chapelles Floating Blue extensively, not the MC6 as do you.
Floating Blue is in reality a varigated blue due to the rutile in it. I
fire it only to cone 5. Hands on experience has clearly demonstrated to
me DO NOT fire it hotter. For me, to fire it above cone five produces
runs all over and a shift to muddy green/gray.
Mind you, this is my experience, and the way I now get it to work for me
in my kilns.
I fire this glaze extremely slow, taking 12 hours to get to maturity in
my kiln. I never put the kiln on Hi Fire, I just bring it up to Hi and
then just let it slowly rise to maturity. I use Orton shelf cone 5 bent
to horizontal. No soak after cone bending. This works for me in my big
Paragon, Crusader and my small Duncan kiln.
Hope this helps.
Regards,
John Rodgers
Chelsea, AL
Michele D'Amico wrote:
>I have a small skutt kiln. I fire to cone 6 or 7 depending on the glaze
>I'm using. I don't have a vent but I leave the kiln propped open and the
>plugs out until about 1100 F. Lately when I fire on medium speed with a
>short soak I'm finding my glazes are getting a 'muddy' look. Some are
>glazes from MC6. My varigated slate blue which was a lovely blue is now a
>cloudy gray. Floating blue is muddy gray. Last night I fired using a
>friend's glaze that has been a bright lime green (like fiesta ware) in my
>kiln in the past and it turned an ugly bilious mud color. Any ideas about
>what's going wrong?
>Michele D'Amico
>damicom@cruzio.com
>
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