[Clayart] glaze pops

[Pfeiffer Fire Arts]

Yes and no. we have been using some of this batch before but this is the first time it was all the newest batch we have. The chips we got was were the clay was very thick. You could hear pinging when we opened the kiln. Two plates cracked in the center, very odd, others did fine except for the craters here and there.

My current guess after reading the mail is that we had lots of problems all at the same time. 
The bisque firing was not a high as I would like, 06 or so when it should be 04. I just did change the relays and elements and for some reason things are not firing even or to the right temp.

 A glaze fix with boron which seems to make things worse and while it seemed to be the same COE as the last batch we make Rod's calculations puts it lower. This could account for the shivering where thick. I also think we need new clay. We do sometimes see a chunk of white at the bottom of the pit but not that common. We will start getting a number of samples today and get started on test them as they come in. 
We will also keep looking for a more fluid glaze.

Lots of work.

Dan & Laurel

-----Original Message-----
From: Clayart [mailto:clayart-bounces at lists.clayartworld.com] On Behalf Of Paul Lewing
Sent: Monday, May 07, 2018 9:42 PM
To: Clayart international pottery discussion forum
Subject: Re: [Clayart] glaze pops



On May 7, 2018, at 5:27 PM, Bryan Johnson <bryj at cheqnet.net> wrote:

Are you using a new batch of clay?

I was wondering the same thing.  In my experience, shivering has been really rare.  Whenever I’ve had an episode of small chips popping off, it’s been an issue with contaminated clay, usually with flecks of plaster or gypsum.  If that’s the case, there’s usually a tiny chunk of white or ivory stuff at the bottom of each pit, and it doesn’t necessarily happen right away.
Paul Lewing
www.paullewingtile.com <http://www.paullewingtile.com/>
www.paullewingart.com <http://www.paullewingart.com/>
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