Alisa Liskin Clausen on wed 9 nov 05
>1. Glaze name: Alligator Black (see CM Sept 05 pp 69).
>
>7.6% Barium Carb
>18.5 Gerstely borate
>6.5 Talc
>2.1 Whiting
>41.3 Custer
>24.0 Silica
>add
>6.8 copper carb.
>8.7 zinc oxide
>86.9 Zircopax
>
>My question is the last item in the mix--86.9 Zircopax--seems way high.
Can
>that be correct?
The glaze called Alligator Green, in CM Sept 2005 is credited to Jayne
Shatz.
When I tested this glaze, I also looked twice at the amount of Zircopax, at
86.9.
After seeing the texture of the glaze, a crawl, I assumed that it could not
be 8.69 as that would not be enough to get this a crawl.
However, 86.7 Zircopax would make a baby eel's skin crawl.
The test shows a very high and textured crawl, similar to the photo in CM.
What defines a glaze is up to the definer. We have a wonderful source of
food safe and stable glazes in Mastering Cone 6 glazes.
John Hesselberth wrote:
Even if the Zircopax amount is a typo and it really is in the more normal
range
of 5-15% this surface treatment would only be suitable on decorative
or sculptural work. It has way too little alumina and way too much
copper to be durable enough to use of functional work.
That percentage is normal for opacifying a glaze, but I will bet the
Zircopax's highly refractory characteristic is why it is being included in
this glaze recipe. Again, even high for that effect. I personally define
a glaze as a material or materials that are fused or melted. After that,
there is a lot to discuss about what glaze fits what parameters and how it
is intended to be used.
I think this particular glaze is sort of a silly glaze because adding that
much Zircopax to any mixture will most likely get it crawl. It is overkill
in that respect. How Jayne came up with that percent, I wonder if there
were line blends? I will bet dollars to donuts that a lot less will do it.
It is an expensive way to achieve a surface that can be achieved, for
instance, by adding 50% Magnesium to almost any glaze.
As far as reading what is printed in CM, it is as printed, 86.9 percent
Zircopax.
After that we can make a lot of tests to get this effect, if desired, with a
lot less expense, and if you want to, no Barium, no Gerstely Borate and half
the Copper.
Best regards from Alisa in Denmark
I will post my glaze tests soon, have some other work to see to.
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