Lili Krakowski on sat 24 jan 98
When I rejoined CLAYART just now there was a thread about soaking fired
glazes --i.e. pots or glaze tiles--in vinegar overnight. This was a test
for leaching of colorants. I am sorry because I missed some of that
thread. Would some kindly person tell me: how effective is this test?
Does it just check for extreme instability or would a teensy weensy bit of
manganese or cobalt leaching out of a dark bleu/black glaze also show up?
And is this regular 5% vinegar from the supermarket or acetic acid? Many
thanks in advance.
Lili Krakowski
Tony Hansen on tue 27 jan 98
>When I rejoined CLAYART just now there was a thread about soaking fired
>glazes --i.e. pots or glaze tiles--in vinegar overnight. This was a test
>for leaching of colorants. I am sorry because I missed some of that
>thread. Would some kindly person tell me: how effective is this test?
>Does it just check for extreme instability or would a teensy weensy bit of
>manganese or cobalt leaching out of a dark bleu/black glaze also show up?
This is just a test to catch extremely unstable glazes. It works best
for
brightly colored ones because slight changes are easily discernable.
Thus if you want to test a white or transparent glaze just put in 5%
cobalt and do the vinegar test on it.
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T o n y H a n s e n thansen@digitalfire.com
Get INSIGHT, Magic of Fire at http://digitalfire.com
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