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how do you patch a cracked kiln shelf?


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#1 docweathers

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Posted 01 December 2012 - 06:04 PM

One of my kiln shelves is developing a crack. is there any way to patch it?

Thanks Larry

Larry

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#2 weeble

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Posted 02 December 2012 - 03:00 AM

I'd like to hear an answer on that too, but I suspect its 'No'
Maryjane Carlson

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#3 bciskepottery

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Posted 02 December 2012 - 09:01 AM

Not sure it can be patched . . . kiln shelves will expand/contract during firing and any filler might crumble and fall into work. You might think about drilling a small hole at the end of the crack . . . that might help the crack from spreading further. A round hole at the end of the crack should eliminate the end point that will continue to grow with additional firings. Use an appropriate drill bit, wear a respirator (you shelf is made up of all the nasties you don't want to breath, and clean up the dust from the drilling with a wet mop, etc. Have not done this myself . . . no cracks is shelves so far.

#4 JBaymore

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Posted 02 December 2012 - 09:13 AM

The fast answer is "no, not really". But you likely can fire with the shelf for a good while if you take some precautions.

Think structurally about the loading when you use it. You likely can stilt the shelf so that the stilt spans the two sides of the crack (or use two stilts close together), then that supports the "intact" portions of the shelf. Load that shelf a bit more lightly than others.

And have a new shelf or two on order.

best,

................john
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Professor of Ceramics; New Hampshire Insitute of Art

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#5 TJR

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Posted 02 December 2012 - 10:29 AM

You could place at least one post under the crack if not two, as John said. Some shelves can last a long time with a crack. Do not place at the bottom of a bung, because, if it fails, you have lost an entire stack.
Think of the shelf as a "spare", and only use it when you run short. There is no real way to fix them, as they just keep cracking.Sometimes shelves crack if they are stacked unevenly, so take a look at your stacking.
TJR[tom]

#6 docweathers

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Posted 02 December 2012 - 01:00 PM

I will try boring a hole at the end of crack and only use it as a baffle at the top of my kiln.

Thanks for all the good advice.

Larry

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#7 Diana Ferreira

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Posted 02 December 2012 - 03:55 PM

I use alumina, and in order to prevent the dust from falling, I stack my shelves (over 20) on top of each other


With a 3 clay props between each shelve!!!

the props prevent damage to the bottom shelves, should any of the shelves have some unevenness on it's surface, and it also prevents the bottoms of the shelves picking up any alumina that could fall on glaze work in the kiln.
Diana
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#8 Idaho Potter

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Posted 02 December 2012 - 06:21 PM

Sort of on the same subject, can deep holes be patched on shelves? I've thought of using kiln patch--the stuff you use to repair soft bricks that have been elbowed--even tried it on one. Fired it (as you would a brick repair) and it had shrunk away from the edges. In fact, it filled the hole until fired and then didn't fit any more. Do you think it would be possible to repatch/refill the same hole and try firing again? Don't have the money to replace shelves right now.

Shirley






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