Monona Rossol on mon 16 mar 98
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Date: Sat, 14 Mar 1998 22:33:38 EST
From: pedresel@3-cities.com
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So what is your definition of "durable"?
The one discussion I found was in Zakin's Electric Kiln Ceramics:
"Utility and Durability
"Glazes vary greatly in durability. Look for glazes that resist
scratches and abraisions and are free from crazing, bubbling and flaking.
"For glazing utilitarian pieces, look for good durability and easy
cleaning. You may want to use shiny or satin shiny glazes because they are
easier to clean than glazes whose surfaces are mat or dry.
"Many glaze materials that encourage rich character and visual
textures also encourage soft, easily worn surfaces. The desire for a
beautiful surface must be balanced against the need for durability.
Ceramists who create nonutilitarian pieces tend to emphasize the look of the
glaze, while those who create utilitarian pieces or work meant for outdoor
sites will favor durable surfaces."
Not exactly a definition or anything that you can measure but sounds sensible.
-- Evan in W Richland WA where it is quite warm.
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Evan's entry demonstrates the huge gap between craft ceramics and
commercial pottery/china technology. The ASTM (American Society for Testing
and Materials) has tests for the following qualities of fired, glazed ceramic
whiteware:
crazing resistance--by autoclave treatment test, C 474
crazing resistance--by thermal shock test, C 554
flexural properties test--C 674
lead/cadmium release--regular ware: C 738, cookware: C 1034 & 1035
impact & chipping resistance--C 368
chemical resistance of glazed ceramic tile--C 650
There are also general ASTM tests for resistance to abrasives and scratching
that can be used for various materials.
The performance of glazes can be quantified. The ceramics industry
formulates its glazes for performance as well as visual appearance. We
obviously can't afford to do this.
Monona Rossol, industrial hygienist
Arts, Crafts and Theater Safety
181 Thompson St., # 23
New York NY 10012-2586 212/777-0062
http://www.caseweb.com/acts/
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