Friday, February 17, 2012

A Glaze for Sweet Life

Remember I said I have yet to choose a glaze for my currently-gestating line, Sweet Life? I have a candidate in mind, although it will need some tweaking: I have here Ingrid Bathe's Clear recipe. I don't think I am revealing secrets by publishing this recipe, since Ingrid hands it out at workshops. Here's the glaze in its original form:

custer feldspar 51%
whiting 9%
zinc ox 8%
strontium 21%
om4 10%
neodymuim 5%
This glaze is rather matte, and blue in the pools, as you can see in the image of Ingrid's plates. I am looking for something icy and with a bluish cast, but maybe not as blue as this. That is fortunate, as the ingredient which is contributing most of the hue is neodymium, which goes for around $60 a pound. So, scratch the neodymium.

Second, I will need to make some adjustments for the soda, per some sound advice I was given recently. So, let's increase the whiting to 15%; at least in one test. In the other I will add 6% dolomite instead. My expectation is that the additional-whiting test will be shinier, and the dolomite-variation test will retain the more matte surface.

And, because I need some source of boron, let's replace the missing neodymium with 5% gerstley borate in both tests. This will have the effect of making the glaze more fluid at the same time it helps protect against the soda vapor. (Which, by the way, quit hating on gerstley, all you gerstley-haters out there. I have had none of the problems of material irregularity that people are talking about...maybe it's a low-fire thing, and I wouldn't understand.)
These changes make our recipe:

custer feldspar 51%
whiting 15%
zinc ox 8%
strontium 21%
om4 10%
gerstly borate 5%

Or, alternatively:

custer feldspar 51%
whiting 9%
dolomite 6%
zinc ox 8%
strontium 21%
om4 10%
gerstley borate 5%
I know those batches don't add up to 100%; I will worry about re-balancing the percentages when I know which one I will be using.

Watch for result 2/26!
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