[Clayart] Slow/Fast Cooling

Eva Gallagher via Clayart clayart at lists.clayartworld.com
Fri Apr 24 09:37:26 EDT 2015

Hi  - our only problem with the slow cool was the fact that some glazes - 
mainly a transparent clear would blister in the firing. In group firings 
such as we have at the Guild it was always difficult to separate out those 
glazes from the SC ones. However I think it was probably over firing when 
holding  - as we were using the Steven Hill program which not only holds in 
slow cool down but also holds  at the top temperature range before the slow 
Eva Gallagher
Deep River, Ontario

----- Original Message ----- 
From: "John Hesselberth via Clayart" <clayart at lists.clayartworld.com>
To: "Clayart international pottery discussion forum" 
<clayart at lists.clayartworld.com>
Sent: Thursday, April 23, 2015 7:38 PM
Subject: [Clayart] Slow/Fast Cooling

>A oouple days ago the comment was made that all glazes benefit from slow 
>cooling and another person asked what about those that don’t form crystals 
>when they cool—why would they benefit? At least that is my recollection of 
>the messages—I can no longer find them in my email.
> My take is that I have never seen a glaze that didn’t form a few crystals. 
> Even a “transparent" glaze will have  a few. And when those crystals are 
> maximized by slow cooling the glaze will seem to have, by my observation, 
> more depth. It will not be as obvious a difference, but I think most would 
> choose that slow cooled glaze over a flat fast cooled one.
> Speaking of an obvious difference you can see some tiles cooled at various 
> rates for the glaze Ron and I called Variegated Slate Blue here:
> http://www.masteringglazes.com/mastering-cone-6-glazes/frequently-asked-questions.html 
> <http://www.masteringglazes.com/mastering-cone-6-glazes/frequently-asked-questions.html>
> Regards,
> John
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