Jody Lebrenz on mon 13 nov 00
I just completed the second of my first two saggar
firings and couldn't have had more opposite results.
The first came out wonderfully--lots of colors and
shades. The second firing came out almost completely
black. The only differences between the 2 firings
were that during the second firing, the saggar had
several cracks, and I packed the sawdust very tighlty
around the piece. I am thinking that possibly air got
into the saggar through the cracks and caused the
firing to turn the pot black. Does this make sense?
Any further suggestions would be greatly appreciated.
jody
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rickmahaffey on tue 14 nov 00
Jody Lebrenz,
Most likely the packing of the sawdust was the problem. Increased air
would make the colors lighter or make them go away completely, so
despite the cracks packing the sawdust tightly more than made up for the
cracks. I fill the cracks just before firing with regular kiln putty
and it seems to work as well as anything.
There is a critical balance between the volume of pot, air and
combustibles. When I out in too much of the combustibles my pots tend
more toward black and white. You should only change one variable at a
time.
The Temperature should be the same as you vary other elements and you
should keep careful notes.
I have been saggar firing since 1977 and have run into most of the
problems possible.
If you have specific questions please email me off the list.
Rick Mahaffey
Tacoma Community College
Tacoma Washington, USA
To see some pictures of some of my saggar fired work
http://www.tacoma.ctc.edu/
go to Faculty on the top
Then scroll down to Rick Mahaffey Art
Then select my work
Ron Collins on tue 14 nov 00
Dear Jody,
I have been doing a good bit of reduction luster saggar fires here in
Guatemala, and have a suggestion to try...do it on small test pieces and see
what happens
I don't know what kind of kiln you are using to fire, but I use my
crank-up Olympic gas kiln...here at high altitudes, I have run into some
problems, and what works for me might not for you but here is a suggestion
or two for better firing.....
first, I don't use clay saggars...I use enamel cooking pots with lids,
fired to 017 on my pyrometer..you get great reduction, the lid can stick and
no air gets in.open with a putty knife....after a few firings, it will open
easier...also, the first time the enamel on the bottom may melt, certainly
will with overfiring, but you can put some bisque tiles, etc, under the pot,
and not have kiln shelf damage..I can't tell you how many times I have fired
the same old enamel pots, and no problems, so much easier.....
Also, you might try not packing sawdust around the pots, I do better
with the pot on a bisque tile above the sawdust and chemicals..it seems to
me that only where there is NOT sawdust will you get results other than
black...I do lusters, and it's more tricky, but I think the same
idea...anyway, good luck...Melinda Collins
----- Original Message -----
From: Jody Lebrenz
To:
Sent: Monday, November 13, 2000 7:10 PM
Subject: Saggar Firing Help
> I just completed the second of my first two saggar
> firings and couldn't have had more opposite results.
> The first came out wonderfully--lots of colors and
> shades. The second firing came out almost completely
> black. The only differences between the 2 firings
> were that during the second firing, the saggar had
> several cracks, and I packed the sawdust very tighlty
> around the piece. I am thinking that possibly air got
> into the saggar through the cracks and caused the
> firing to turn the pot black. Does this make sense?
>
> Any further suggestions would be greatly appreciated.
>
> jody
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Calendar - Get organized for the holidays!
> http://calendar.yahoo.com/
>
>
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Linfield College on tue 14 nov 00
on 11/13/00 5:10 PM, Jody Lebrenz at jlebrenz@YAHOO.COM wrote:
> I just completed the second of my first two saggar
> firings and couldn't have had more opposite results.
> ....second firing came out almost completely
> black. ....I packed the sawdust very tighlty
> around the piece. I am thinking that possibly air got
> into the saggar through the cracks and caused the
> firing to turn the pot black. Does this make sense?......
>
It is much more likely that either the second firing was
not as hot, in which case the carbon did not burn out
of the clay; or, that the additional sawdust simply did
not all burn out, and as the temp cooled more carbon
got sucked into the clay because the sawdust was still
smoldering.
regards
Dannon Rhudy
Terpstra Karen K on wed 15 nov 00
Jody,
I'm guessing the sawdust acted as too much insulation and the work
didn't get hot enough to burn off the carbon. Cracks in the saggar is
usually a good thing. The material needs plenty of air to make it burn.
Try refiring, use less saw dust and pack loosely. Hay, straw, wood
chips, small pieces of junk wood etc. can be packed easily around work.
My favorite: any kind of used bedding from the horse stall. Mmmm... the
minerals in that stuff. A great way to recycle!
Karen Terpstra
Assistant Professor of Art/Ceramics
University of Wisconsin-La Crosse
1725 State Street
La Crosse, WI 54601
Date: Mon, 13 Nov 2000 17:10:13 -0800
From: Jody Lebrenz
Subject: Saggar Firing Help
I just completed the second of my first two saggar
firings and couldn't have had more opposite results.
The first came out wonderfully--lots of colors and
shades. The second firing came out almost completely
black. The only differences between the 2 firings
were that during the second firing, the saggar had
several cracks, and I packed the sawdust very tighlty
around the piece. I am thinking that possibly air got
into the saggar through the cracks and caused the
firing to turn the pot black. Does this make sense?
Any further suggestions would be greatly appreciated.
jody
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