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question re: copper reds

updated fri 31 jan 97


Erin Hayes on thu 23 jan 97

One of my advanced students has been digging through books and found the
book "Glazes for Special Effects" by Herbert Sanders. I have a question
about the section on Copper Reds, where Sanders syas that you should,
"Prepare only as much glaze as you are going to apply at the time," due
to what he calls recrystallization of the soluble materials in the
glaze. He says that glazes stored wet will not fire the same as
fresh-made glazes.

I have never heard this sort of statement before, andI am curious to hear
what you guys have to say about it. Is it something special about Copper
Reds? I never use a glaze right after it is mixed! I always thought it
needed time to hydrate completely...Hmmmmm.


Erin Hayes, Art and Humanities Instructor Office: (509) 574-4844
Yakima Valley Community College School E-mail:
PO Box 1647 Home E-Mail:
Yakima, WA 98907 "Clay is Good."

Rick Sherman on sat 25 jan 97

Erin: You ask about Herbert Sanders instructions in "Glazes for
Sepecial Effect" to use the copper red glazes immediately because
there will be a "re-crystallize " is allowed to set for a time. If
you look at the glaze formulas in the text, pp 59-64, you will find
all but two contain borax and/or calcined borax and only two do not
contain sodium silicate. These are soluable materials. When the
glazes sit, water evaporates and the water ratio is reduced and there
is a supersaturated solution of soluable material which sets up as
crystals. Some glazes do just fine sitting around. His needed to be
used immediately. Try some. I think the local ruduction ones are the
best - some created by Dwayne Bentzien for his MA thesis. RS