[Clayart] glaze pops

[Vince Pitelka]

Hi Dan - 
Can you be more clear about what you are referring to as glaze pops?  I am familiar with lime pops, which are usually the fault of the claybody (limestone contamination) or plaster contamination.  I am not familiar with "glaze pops." 
- Vince

Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka at dtccom.net  
sites.tntech.edu/wpitelka/

On Mon, May 7, 2018 at 1:03 PM, Pfeiffer Fire Arts <firearts at ardmore.net>
wrote:

> All,
>
>
> After a number of years of not having a lot of problems with pop's in 
> the glaze it has got so bad as to put us out of business. I have been 
> making small changes in our glaze to reduce the surface tension hoping 
> this would help. It has not and the last firing was the worst of the 
> lot. I am not sure there are 5 pieces that we can sell.
> This firing had a slow rise from 1700 to 1900 and then a hour dwell at 
> the top to cone 10 - 11. When slow about 2000 to give things time to 
> heel. If anything the pops are bigger with our new glaze then the old one.
>
> Our first glaze base glaze is:
>
> Epk                     12
> Petalite                14
> Wollastonite    20
> Silca             20
> Custer          33
> Bentonite               1
>
> Our most recent attempt is to add a frit:
>
> Epk                     6
> Cal Epk         6
> Petalite                15
> Wollastonite    17
> Silca             20
> Custer          29
> Bentonite               .5
> Ferro 3134              6
> Veegum          .5
>
> While the calculated CEO is very close (8.60 and 8.61) to the same for 
> both versions we had some shivering when it was thick on one piece.
> Anyone want to guess what to do next.
>
> Dan
> PfeifferFirearts.com
>
>
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