Jump to content


Photo
- - - - -

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


  • Please log in to reply
5 replies to this topic

#1 oly

oly

    Advanced Member

  • Members
  • PipPipPip
  • 46 posts
  • LocationKent, England

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

Biglou13

    Advanced beginner pottery, Advanced in other art

  • Members
  • PipPipPip
  • 1,042 posts
  • LocationNorth Florida

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!
  • oly likes this
Caution big brother is watching.
The beige is blinding!!!!!!
The middle of the road is boring

The true sign of intelligence is not knowledge but imagination.
-Albert Einstein

#3 TJR

TJR

    Advanced Member

  • Members
  • PipPipPip
  • 1,294 posts
  • LocationCanada

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?

Tom.


  • oly likes this

#4 sankayknow

sankayknow

    Newbie

  • Members
  • Pip
  • 1 posts

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.


  • oly likes this

#5 neilestrick

neilestrick

    Neil Estrick

  • Members
  • PipPipPip
  • 2,807 posts
  • LocationGrayslake, IL

Posted 19 August 2014 - 08:23 AM

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


  • oly likes this
Neil Estrick
Kiln Repair Tech
L&L Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com

#6 Brian Reed

Brian Reed

    Advanced Member

  • Members
  • PipPipPip
  • 209 posts
  • LocationWashington State

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. 


  • oly likes this
Brian Reed

Throwing down in Washington State

http://www.reedpottery.com

Northwest Clay Club




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users