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cracked slit in a kiln shelf

updated tue 22 oct 02

 

barbara arner on sat 19 oct 02


I have a broken kiln shelf - well it's more of a crack about two inches from the edge. i just realized this after my firing and i dont know when it occurred - my quesiton is, can i still use it or will it spilt and shatter in my electric kiln? i went on the safe side and didnt use it but has anyone before? it is a rather large one i'd like to have for the next firing and i'm running out of time. any idea? thanks for answering this quick question.
-barbara

Philip Poburka on sat 19 oct 02


If you may have a Stilt situated beneath the (end of the)
crack, as supports both sides of it...and two more further
on where it may go if it were to lengthen itself...

As well as the other Stilts situated as one would have
them...

That's what I'd do...

Phil
Las Vegas

----- Original Message -----
From: "barbara arner"
To:
Sent: Saturday, October 19, 2002 5:28 PM
Subject: cracked slit in a kiln shelf


I have a broken kiln shelf - well it's more of a crack about
two inches from the edge. i just realized this after my
firing and i dont know when it occurred - my quesiton is,
can i still use it or will it spilt and shatter in my
electric kiln? i went on the safe side and didnt use it but
has anyone before? it is a rather large one i'd like to have
for the next firing and i'm running out of time. any idea?
thanks for answering this quick question.
-barbara

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Rikki Gill on sat 19 oct 02


Hi Barbara, What I have done, is to paint the crack with a little red iron
oxide, just to show you where it ended this time, since it isn't too long
yet, and continue to use it. You don't say how high you fire. Probably,
you are safe for at least one more firing, but just be sure to keep checking
on its length. Some cracks never seem to get any longer. Also, avoid
placing kiln posts right on the crack. Good luck,
Rikki in Berkeley
----- Original Message -----
From: "barbara arner"
To:
Sent: Saturday, October 19, 2002 5:28 PM
Subject: cracked slit in a kiln shelf


> I have a broken kiln shelf - well it's more of a crack about two inches
from the edge. i just realized this after my firing and i dont know when it
occurred - my quesiton is, can i still use it or will it spilt and shatter
in my electric kiln? i went on the safe side and didnt use it but has anyone
before? it is a rather large one i'd like to have for the next firing and
i'm running out of time. any idea? thanks for answering this quick question.
> -barbara
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>

Gail Dapogny on sun 20 oct 02


We have used cracked silicon carbide shelves for years, MANY years.. Don't
know about other materials. I try to support crack with stilt underneath,
but I know that sometimes it is put in unsupported. The cracks do not
appear to change or lengthen. It just keeps going and going and going...
---Gail


>I have a broken kiln shelf - well it's more of a crack about two inches
>from the edge. i just realized this after my firing and i dont know when
>it occurred - my quesiton is, can i still use it or will it spilt and
>shatter in my electric kiln? i went on the safe side and didnt use it but
>has anyone before? it is a rather large one i'd like to have for the next
>firing and i'm running out of time. any idea? thanks for answering this
>quick question.

Gail Dapogny
1154 Olden Road
Ann Arbor, MI 48103-3005
(734) 665-9816
gdapogny@umich.edu
http://www.silverhawk.com/ex99/dapogny (single historical photo - no longer
registered with Silverhawk)

David Hendley on sun 20 oct 02


A cracked kiln shelf can be used for years, no decades, with no
ill effects. Of course, there are no guarantees, and it could break
at any time, but this could also happen with an un-cracked kiln shelf.

The offending shelf will definitely not "shatter" in a spectacular
apocalyptic episode. If it breaks it will just crack more and quietly
fall apart. A two-inch long crack is so small as to be practically
insignificant. I think you would see the crack continue to grow
long before the crack becomes a break.
If you're still worried, just put an extra kiln post under the shelf,
bridging the crack.

Virtually 100% of my 25-year old silicon carbide shelves are cracked.
Many on two sides, with cracks up to 10 inches long.
Only had one break in the last 10 years.

David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com




----- Original Message -----
From: "barbara arner"
To:
Sent: Saturday, October 19, 2002 7:28 PM
Subject: cracked slit in a kiln shelf


> I have a broken kiln shelf - well it's more of a crack about two inches
from the edge. i just realized this after my firing and i dont know when it
occurred - my quesiton is, can i still use it or will it spilt and shatter
in my electric kiln? i went on the safe side and didnt use it but has anyone
before? it is a rather

Snail Scott on sun 20 oct 02


At 08:28 PM 10/19/02 -0400, you wrote:
>I have a broken kiln shelf...can i still use it or will it spilt and
shatter in my electric kiln?


It might last for years, or not. Treat it gently
by not putting large or heavy things in the
cracked region, and if possible put extra posts
below it, to support it if it does give way.
And use it as the top shelf in the stack, so
that there is no shelf above is that might be
affected if it gives way.

-Snail

Edouard Bastarache on sun 20 oct 02


Hello David,

what are the sizes of your silicon carbide shelves?


Later,



Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm


----- Original Message -----
From: David Hendley
To:
Sent: Sunday, October 20, 2002 12:15 PM
Subject: Re: cracked slit in a kiln shelf


> A cracked kiln shelf can be used for years, no decades, with no
> ill effects. Of course, there are no guarantees, and it could break
> at any time, but this could also happen with an un-cracked kiln shelf.
>
> The offending shelf will definitely not "shatter" in a spectacular
> apocalyptic episode. If it breaks it will just crack more and quietly
> fall apart. A two-inch long crack is so small as to be practically
> insignificant. I think you would see the crack continue to grow
> long before the crack becomes a break.
> If you're still worried, just put an extra kiln post under the shelf,
> bridging the crack.
>
> Virtually 100% of my 25-year old silicon carbide shelves are cracked.
> Many on two sides, with cracks up to 10 inches long.
> Only had one break in the last 10 years.
>
> David Hendley
> Maydelle, Texas
> hendley@tyler.net
> http://www.farmpots.com
>
>
>
>
> ----- Original Message -----
> From: "barbara arner"
> To:
> Sent: Saturday, October 19, 2002 7:28 PM
> Subject: cracked slit in a kiln shelf
>
>
> > I have a broken kiln shelf - well it's more of a crack about two inches
> from the edge. i just realized this after my firing and i dont know when
it
> occurred - my quesiton is, can i still use it or will it spilt and shatter
> in my electric kiln? i went on the safe side and didnt use it but has
anyone
> before? it is a rather
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.

william schran on sun 20 oct 02


Barbara - Where is the crack in the shelf? is it where you can line
up posts over and under? I have several smaller octagonal shelves
that are cracked and have been using them for many years. I just make
sure I position posts where the cracks are.
Bill

David Hendley on sun 20 oct 02


----- Original Message -----
> Hello David,
> what are the sizes of your silicon carbide shelves?
> Edouard Bastarache

They are 12 X 24 X 3/4 inches.
On some of them, one side of the crack is lower than the other
by a good 1/8 inch. Since they are heavily coated with kiln
wash for the wood kiln, that helps to even it up.
The gap between some of the cracks is close to 1/4 inch.
Again, I just put on lots of coats of kiln wash and it fills
the void.

David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com

Alan D. Scott on sun 20 oct 02


Barbara:

I had such a shelf. I continued using it as I didn't know better. With
each firing, the crack got bigger and bigger. I soon figured it out and
stopped using it. Some time later, I examined it. When I held it a certain
way (without applying any noticeable pressure), it broke.

My advice: throw it out and buy an new one. Don't risk your cherished pots
and glazes on it.

Alan

Alan D. Scott
The 3rd Cup Clayworks
Parker, AZ
N 34 8.525' W 114 17.635'
(North of Catherine & Alan at the Mexican border, South of Raku Karin in
Havasu)


-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of barbara arner
Sent: Saturday, October 19, 2002 5:28 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: cracked slit in a kiln shelf


I have a broken kiln shelf - well it's more of a crack about two inches from
the edge. i just realized this after my firing and i dont know when it
occurred - my quesiton is, can i still use it or will it spilt and shatter
in my electric kiln? i went on the safe side and didnt use it but has anyone
before? it is a rather large one i'd like to have for the next firing and
i'm running out of time. any idea? thanks for answering this quick question.
-barbara

____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org

You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/

Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.

Tommy Humphries on mon 21 oct 02


drill a 1/2" hole at the inner end of the crack to relieve the stress at
that point, and you will have no problem with the crack becoming any
longer.

Tommy


----- Original Message -----
From: "barbara arner"
To:
Sent: Saturday, October 19, 2002 7:28 PM
Subject: cracked slit in a kiln shelf


> I have a broken kiln shelf - well it's more of a crack about two inches
from the edge.