dayton j grant on wed 24 apr 02
I know 'exactly' what could happen if someone overfires a kiln made of
IFB's.
allright....to make a short story long ....I was trying out a new kiln
design (powerdraft) and I was warned not to take my eyes of it for even a
minute ,and ,well thats about all it took ,I looked in the peephole and
it was at cone 9(in a series of cones including ^1,^5,^9,^10,^11,^12
and^14) I walked about twenty feet away where I could still hear the dull
roar of the burners and see the bright white 'diamond color' light coming
out of the burner ports and a few cracks (It looked like an 'alien' or
something 'unbeleivable' was in the box) I had never seen that color
light before and I was just staring at it thinking "Wow ,this is 'far
out',man",when I wondered if I heard a funny sound ,and ,'shazam!'a peice
of the arch against the back wall fell into the kiln with a weird roar
and a menacing blast of flame, a beam of this super bright light went
straight up into the sky for a couple of seconds like it was 'alive' and
it was 'escaping' or 'making a break for it',and within a couple of
seconds the light changed back to a normal yellow white, so I ran over
and shut off the gas, and since there was a big hole in the top of the
kiln the temp dropped right away but the heat was unbearable within five
feet of the kiln and half of the leaves on a tree ten feet away were
instantly wilted and crispy,It continued to make scary sounds all night
but nothing else happened ,oh and I lost all of the shelves ,the pots and
most of the bricks,IFB's are great up to a point but when you pass that
point they boil, shrink and distort like styrofoam ,(I 'know' because I
tried to 'cut' some with an acetylene cutting torch but I couldnt get
them to 'melt' in a straight line, they just shrink in a random pattern
when overheated ) and I just love talkin about stuff like that,anyways
...'whatever'...<;0 )
Jeff Lawrence on wed 24 apr 02
Hello Clayart,
I've got a bunch of pots I overfired but I got inspired about what
to do. I put them all in the freezer to Un-Fire (Registered Process;
PatentsnPending). Hey, we were going to toss those leftovers in a
year or two anyway!
Here's a question, though: can I over-un-fire them? If I leave them in
too long will they revert completely to dry clay? granite?
Even more important, if there is manganese in the claybody, how will it
affect the gimlets I make with the frozen wodka I couldn't bear to
throw out?
getting concerned in the southwest usa ...
Jeff
Earl Brunner on wed 24 apr 02
Dayton, I'm curious, what were these specific IFB's rated to? Another
thought I
had as I read it was whether or not the arch failure was related to
overfiring or
not. Depending on how the arch was built a single brick that didn't fit
well,
especially if there were straights in the arch could cause arch failure.
This
might be the case especially at high temperature when things have expanded.
You didn't provide a lot of details, some of what you said suggested that
the brick
actually melted. There are some IFB's that are rated to 2300 F. which cone
10
potters often try to use to save money (there is a significant change in
price for
the higher refractory bricks, ar at least their used to be). Those lower
temperature brick will generally work OK at cone ten, (I think there is a
certain
margin for error built in) but even in normal firings, they will show the
progressive damage from extended heat work over time.
dayton j grant wrote:
> I know 'exactly' what could happen if someone overfires a kiln made of
> IFB's.
> allright....to make a short story long ....I was trying out a new kiln
> design (powerdraft) and I was warned not to take my eyes of it for even a
> minute ,--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
vince pitelka on wed 24 apr 02
Just after I arrived at the Craft Center eight years ago, I replaced the old
decrepit downdraft with a new 45-cubic-footer with a hinged door. We spared
no efforts in building that kiln, and it was a beauty. The next year I had
a new student arrive in a whirlwind of energy and creativity. He looked
like he might be one of the great ones. Through most of the fall semester
this student was an integral part of a really wonderful studio dynamic, with
lots of very productive group firings. But at the end of the fall semester
something started to go sour. I subsequently found out that he had done the
same thing in a half dozen different schools in succession - sort of
self-fulfilling failure. As his behavior started to deteriorate I tried to
talk to him about it, but he was surly and silent.
Early in spring semester he fired a load of his own work in the new
downdraft, and around noon he finished body reduction, cranked up the
power-burners way more than necessary, and went back to his housing unit and
went to sleep with no alarm clock. It was a quiet day with few people
around, with no one there to recognize that something was amiss. I was out
of town that weekend.
Finally he woke up, and with a sh-t-eating grin said to his roomate "Oops, I
think I might have just melted a gas kiln." He headed over to ceramics, saw
the white light coming from the spy ports, and shut down the kiln.
When I returned the next day he came up to me and said, with the same
sh-t-eating grin on his face, "Your not gonna like what I did to your kiln."
I asked him what he was talking about, and he just told me to go look at the
downdraft kiln. He was still smiling. I went in and looked in the kiln and
my heart sank. The dozen or so 1" high-alumina shelves were all slumped,
and the only thing holding them up was the pots themselves. He had been
using a claybody which was still completely immature at cone ten, and I had
been trying to get him to change it, but he refused. That's what kept the
shelves from just tumbling down to the floor of the kiln. Worst of all, the
surface of the IFB interior looked like cottage cheese, all bumpy and
curdled. Gaps had opened between some of the arch bricks, and a number of
them were hanging down slightly, looking very precarious.
He never appologized, never was willing to talk about it or take
responsibility for his actions. Things got worse through the semester, as
he ran roughshod over all of his studio mates. They all quit talking to
him. At the end of the semester I delivered a written evaluation to him and
to the Director of the Craft Center. I still knew that he was capable of
great things, so I told him to go away for the summer, and if he could come
back in the fallm pay for the ruined shelves, and return to his former
persona, as a productive, contributing part of the studio dynamic, then he
would be welcome. The next day all of his stuff was gone from the studio
and I heard second hand that he had been telling everyone that I had kicked
him out of the program. Hmmmmm. Self-fulfilling failure.
But you know what? I injected patching mortar in the gaps between the arch
bricks (which is easy to do), and that kiln has not changed a bit in the
intervening six and a half years. He probably fired it to 2800F or so, and
the hotface of the insulation bricks suffered, but the walls are 9" of
insulation brick, so it didn't affect the insulating capabilities or the
outside of the kiln at all. It still fires like a dream.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Earl Brunner on thu 25 apr 02
Jeff, you got WAY to much free time (or freezer space).
I'm in the south west, I just had a great idea! Lets average the
temperatures
through out the year, then it would never REALLY be 120 degrees in
July........
Jeff Lawrence wrote:
> Hello Clayart,
>
> I've got a bunch of pots I overfired but I got inspired about what
> to do. I put them all in the freezer to Un-Fire (Registered Process;
> PatentsnPending). Hey, we were going to toss those leftovers in a
> year or two anyway!
>
> Here's a question, though: can I over-un-fire them? If I leave them in
> too long will they revert completely to dry clay? granite?
>
> Even more important, if there is manganese in the claybody, how will it
> affect the gimlets I make with the frozen wodka I couldn't bear to
> throw out?
>
> getting concerned in the southwest usa ...
> Jeff
>
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
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