[Clayart] tony's metaphor tangent - cornwall stone vs custer mega-pinholes

Jeff Lawrence jefflawr at gmail.com
Thu Mar 6 00:45:08 EST 2014

A real-life vignette:
Kathleen: What do you suppose is happening with this glaze? It behaved
perfectly but now it's  pinholed on one side.
<Val Cushing's Blue Green
1380 Cornwall Stone
1020 Whiting
600 EPK
120 tin oxide
120 copper carbonate
Jeff <channeling Tony>: No idea, but it's a long swim for all that Cornwall
Stone. Let's make it with somethign  more local.
< Two spot-on oxide matches ensue from Glazemaster, one with G-200 and one
with custer - here's one:
298.3 custer feldspar
1053.9 whiting
772.3 epk
421.3 neph sy
454.2 silica
120 tin oxide
120 copper carbonate
<upon opening after the 10R firing  this morning >
Whoa! Both those tests are gaudy (and runny) turquoise lava glazes on flat
pieces and run off a test cup (Original was a mat turquoise).  Wuzzup with
<vignette mode off>
This shows why normal people like stuff that works no matter how long the
haul to get it, but me, I get sidetracked - why the frozen froth in the
tests when the oxide balance was so close? What's bubbling? I thought
whiting lost its CO3 well below  cone 10.
Theories, please!
tangentially yours,

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