Dave Finkelnburg on wed 14 feb 01
It sounds like you are simply underestimating how much kaolin you need
in this glaze.
Typical hardwood ash (per Wolff via Tichane's "Ash Glazes) is about 70%
flux. If you calculate a Seger formula for 50:50 hardwood ash and Redart,
you get something with approximately .1 alumina, .7 silica. I would suggest
you do a line blend, or better a Currie grid tile, with 10 to 50% kaolin. I
don't know how far you want to go in stiffening up this glaze, but this
could get you in the ballpark in one firing of test tiles. Then you could
focus on a much smaller variation and run another set of tests.
Your glaze, as is, may be better suited to layering or thin application
than as a glaze by itself, given the high flux, low amount of glass former
I hope this is helpful.
Dave Finkelnburg in frosty Idaho
From: aaron tester
>i AM HAVING A PROBLEM WITH A GLAZE!
>The glaze is a 50/50 mixed wood ash (hardwood) adn Cedar Heights Red Art,
>and it is running like mad...I have been adding Fla. Kaolin in incriments
>about 2% at a time, but it is still running.