Super slow cool

I fired a glaze load on Sunday. It was full of two combinations, Waterfall Brown over Oatmeal, and Waterfall Brown over Bright Sky Blue. Normally I follow the revised Roy & Hesselberth schedule, but on Sunday I just about feel asleep at 7:30 pm after working in the sun all day while watching a documentary on bill fish, and went to bed while the kiln was at 45% power. When I woke up ten hours later I finally remembered.

Ooooops. The kiln cooled from 1050 C to 800 C from about 6pm to 8 pm when I finally turned it off

The R&H matte glazes are such that they require slow cooling to turn matte. It's a generalization to say it's because of stability issues, but it is largely true. Unfortunately, it turns out that extreme slow cooling makes Oatmeal look quite boring. It's a completely uniform and dull oakish colour.

The glossy glazes on the other hand require slow cooling to reduce their glossiness a little. The slow cooling allows some crystals to grow which adds interest. If you extend that slow cooling it seems you might get a matte glaze. I'm very happy to report that this extremely slow cooling makes Bright Sky Blue a much more interesting glaze. It turns completely matte with creamy speckles in it; moreover it has a very interesting texture.

The pots in this firing are so beautiful that I'm going to use this schedule for this glaze from now on. Of course, this means that I have to glaze a full load with all the same glaze, but it will be worth it.