Slow Cooling

[Norm Stuart]

Gas kilns use hard fire-brick which cool far more slowly than the foam-core brick used in electric kilns. Many here have suggested this is one major difference in the "cone 10" look of a gas kiln.

Using our Cress E23 computerized kiln controller we slow the rate of cooling between 1,800F and 1,500F.

Over the past two years I have used three different cooling rates: 185F per hour, as suggested in "Mastering Cone 6 Glazes"; 100F per hour; and 50F per hour. We finally settled on 50F as the rate we preferred.

Some glazes become so crystallized and matte at 50F cooling I need to add 10% Ferro Frit 3268, or slightly more, to give them enough flux and silica to retain their look.

These are photos of Ron Roy's Sapphire cooled at 185F, 100F, and 50F.

[Norm Stuart]

Kathryn - All of the recipes for the glazes I use are available on George Lewter's Insight Live Users Group. Send George an email to join at this link, and he'll send you a log-in ID.

http://cone6pots.ning.com/group/insight-live-users-group

This is the website of Jayne Shatz, whose glaze this is.  -  http://www.jayneshatzpottery.com/

And this is the recipe in Insight Live

Kathryn Reedy said:

Hi,Norm,

I've searched to the end of the internet for this recipe (Shatz Blue Matte)with no luck! Can you share the recipe?

Thanks!


Norm Stuart said:

Another typical difference between slow-cooling at 185 F/hr and 50 F/hr with Jayne Schatz Blue Matte.