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ron/john glaze testing

updated tue 19 nov 02

 

Dewitt on mon 18 nov 02


I glazed fired a number of test pieces with some of Ron/John's glazes this
weekend with generally good results.

The test pieces were made from Armadillo's Cinco Blanco (white stoneware)
and Buffalo Wallow (light brown stoneware) cone 5-6 clays. I didn't see
any of the slumping or bloating that Wanda reported with these clays, but
then only firing glaze mice and 2.5 inch test cups. Not having either a
computerized kiln or a thermocouple, I followed the suggestion in the book
and turned the kiln to medium after cone 6 went down, leaving it there for
4 hours before turning it off. All the glazes looked better on Buffalo
Wallow except for Waterfall Brown which had more color and movement on
Cinco Blanco. Waxwing Brown looked overfired, dry and starting to bubble
on Cinco Blanco, but was fine on Buffalo Wallow.

The biggest surprise was Licorice. It came out with a tea dust effect,
especially where thinner. (I have a pic if anybody wants to see it.) Not
the solid black I was expecting, but I like it. I'm guessing that a faster
cooling would yield a more pure black.

Raw Sienna was another surprise - it came out almost bean pot brown and
flowed away from the rim. However, I had mixed up a version with 1/2 the
iron of Raw Sienna. It came out a nice light honey color with a heavy
frosting of lighter crystals - sort of a fossilized Bone.

I overdipped some of the glazes with a 1/2 inch or so of others. Some were
interesting, others atrocious. Many, such as Licorice over Clear Powder
Blue, showed lots of movement with swirls of the top glaze color flowing
down to the bottom of the base glaze. Several combinations looked like
they might tend to run off a pot.

deg

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Dewitt Gimblet
Austin, Tx
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