Donna Kat on thu 29 nov 07
A bit back I reported a glaze having been mixed improperly and crawling
badly. I tried two fixes - each with 500 ml of the flawed glaze batch.
In one, since the glaze was low in silica to begin with, I simply added
silica to the glaze (bringing silica up to 2.5 in the unity measure). In
the first testing this worked. but further testing showed it still had a
tendency to crawl. In the second testing I followed the fix for MC6
licorice which for some had crawled. I mixed up an equal batch of glaze
modeled on Ron Roy's/John Hessleberth's formula which used calcinated EPK
with the my addition of added silica to improve the glaze (again working
on a 500 ml batch with a density of 1.4 = 337 gms of dry weight). This
has been tested and re-tested and knock on wood seems to have worked. The
glaze continues to be a matt black glaze but now has to me a more pleasant
buttery texture and has enough silica to potentially be a more functional
glaze.
I would like to thank John and Roy for their work which made this
possible.
Donna
//////Original Glaze with one of the ingredients mismeasured//
Rudy's Black,
Feldspar - Custer ,4920.00,
Kaolin - EPK ,1990.00,
Whiting ,1790.00,
Zinc Oxide ,800.00,
Flint ,500.00,
Cobalt Oxide ,130
Iron Oxide - Red ,670
////////////////Reformulated - mixed with equal volume of bad glaze
DK's Rudy's Black Fix,
Feldspar - Custer ,208.00,
Kaolin - Calcined ,77.00,
Whiting ,77.00,
Zinc Oxide ,34.00,
Flint ,104.00,
Cobalt Oxide ,6.50,
Iron Oxide - Red ,33.50,
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