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Base Of Pots 'chipped Edge' After Glaze Firing - Why?

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#1 oly


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Posted 18 August 2014 - 04:41 AM

The attached picture shows the chipping that has occurred to the bottom edge of pots as they have come out of glaze firing (c1240 degrees centigrade – cone 6-7). The edge was perfectly smooth when it went in the kiln.


Larger pots affected worse than small ones.


Clay has some grog in it.


There is a layer of bat wash on the kiln shelves.


Any help gratefully received!

Attached Files

#2 Biglou13


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Posted 18 August 2014 - 05:14 AM

Could be pluckng?
What kind of clay?
That's not a problem, a few passes with diamond pad and you're back to new.
Try putting some silica on shelf before next firing. See if it does it again?
Did all pots have this!
Caution big brother is watching.
The beige is blinding!!!!!!
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#3 TJR


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Posted 18 August 2014 - 08:56 AM

The term is "plucking". It happens with porcelain quite frequently. When waxing the feet of my porcelain bowls, I put a bit of alumina hydrate in the wax. Problem solved?


#4 sankayknow



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Posted 18 August 2014 - 02:29 PM

I had this happen recently.  My chips were much larger and could not be sanded out too look decent enough for selling.  I have never had it happen before.  I lost about 4 mugs to this.  The studio manager thought it might have been due to the kiln wash being too thin on the shelf, or at least needing to be redone.

#5 neilestrick


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Posted 19 August 2014 - 08:23 AM

You need a fresh coat of kiln wash on the shelves.

Neil Estrick
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Owner, Neil Estrick Gallery, LLC


#6 Brian Reed

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Posted 19 August 2014 - 03:37 PM


I do not use Kiln wash I simply brush a light dry coat of Alumina Oxide on my shelves and call it good.  No more chips on my large porcelain bowls.  I believe this happens during cooling where the pot cools at a different rate than the shelves while the pot has stuck slightly to the shelf. 

Brian Reed

Throwing down in Washington State


Northwest Clay Club

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