Lesley Alexander on wed 3 apr 02
In the latest issue of Clay Times, Pete Pinell has an article on his
Strontium Matt Glaze 29. He also points out that volume testing eases
trying different added oxides... But I am puzzled as to how that works.
If you have a sample containing 4.4% iron oxide and another with 6.7%
titanium dioxide, and add together equal portions by volume, wouldn't
you get a glaze that is 2.2% iron oxide and 3.35% titanium dioxide? Or,
you could double the oxides in each of the original samples if you test
for just two oxides, or triple if you want to test for three... I wonder
if anyone knows his approach or would be interested in his clarifying
that in a future article.
Unfortunately my server doesn't reach his email so I can't ask him
directly. Lesley
Jennifer F Boyer on wed 3 apr 02
You're on the right track. You'd use a smaller amount of oxide
based on how many parts of glaze you were combining. Pete's
point was that volumetric measuring is easier than dry weighing
of ingredients when doing large numbers of tests of oxides in
one base glaze. I mix a batch of test glaze, then divide it
among several different cups in equal volume(CC's). It's easy
to figure out roughly how much weight in water it took to make
your batch. Then you can figure out how many grams of different
oxides you should add to each different cup, one oxide to each
cup to come up with a certain percent of oxide in that cup.. So
if you have 4 percent iron in one cup and 4 percent titanium in
another, if you measure out 10CC's of the iron mixture and
10CC's of the titanium mixture and mix together, you now have
the base glaze with 2 percent iron and 2 percent titanium. A
large animal syringe without the needle is a great tool for
measuring out small amount of glaze by volume. I recently did a
test like this with 6 different oxides, ending up with about 30
different combos of oxides...fun.
Jennifer
Lesley Alexander wrote:
>
> In the latest issue of Clay Times, Pete Pinell has an article on his
> Strontium Matt Glaze 29. He also points out that volume testing eases
> trying different added oxides... But I am puzzled as to how that works.
> If you have a sample containing 4.4% iron oxide and another with 6.7%
> titanium dioxide, and add together equal portions by volume, wouldn't
> you get a glaze that is 2.2% iron oxide and 3.35% titanium dioxide? Or,
> you could double the oxides in each of the original samples if you test
> for just two oxides, or triple if you want to test for three... I wonder
> if anyone knows his approach or would be interested in his clarifying
> that in a future article.
> Unfortunately my server doesn't reach his email so I can't ask him
> directly. Lesley
>
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Thistle Hill Pottery
95 Powder Horn Glen Rd
Montpelier, VT 05602 USA
802-223-8926
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