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controlling crackle size

updated sun 25 jul 99


Jeff Lawrence on fri 23 jul 99

Bruce Girrell was discussing crackle size...looking for the big island effect

Hi Bruce,

You've broached an interesting thread. I didn't pursue this directly, but
did perform the following tests as soon as I got Insight.

I spent a couple of hours concocting recipes for ^04 with Insight that had
coe values that ranged from 7.0 to 9.0 with step of .1. My goal was to
figure out what magic number would work on my slip recipe to eliminate
crazing without giving rise to the shivering problems I was having.
Unfortunately, I made all the tests within the limits for glossy glazes and
was unable to make the glossy glazes shiver even when the calculated coe
was way lower than guaranteed shivering mat glazes.

Pertinent to your topic, however, I definitely saw crazing decrease as I
moved down in calculated value from fine-mesh to large islands to
occasional stress cracks to craze-free.

You might try squeezing that coe down some more.

Or maybe the rate of cooling is the more germane factor? Please apprise the
list of what you come up with.

Best regards,

Jeff Lawrence Sun Dagger Design Rt. 3 Box 220 Espanola, NM 87532
vox 505-753-5913 fax 505-753-8074