earlk on sun 23 jul 06
Since it was too hot to do much else,
(my gosh, it hit 90+ two days in a row)
I was reading about glass:
"When the bubbles are all larger than
pin heads, turn the temperature down
to 50-100 (28-56C) below your working
temperature to squeeze the bubbles out."
and
"The bubbles disappear into the glass. Magic!"
Hmmm? A way to reduce pinholing?
( http://www.cowtown.net/mikefirth/batch.htm )
No PhD in ceramics technology but you want to
know more about the structure of glass? Here's
an interesting and easy read that anyone who
understands a little about glass formers, fluxes
and such can learn from. And the glass flowers
they are talking about are fascinating too.
http://www.rps.psu.edu/sep99/glass.html
earlk...
bothell, wa, usa
Snail Scott on mon 24 jul 06
At 09:15 PM 7/23/2006 -0700, you wrote:
>I was reading about glass:
>
>"The bubbles disappear into the glass. Magic!"
>
>Hmmm? A way to reduce pinholing?
Glass, like glaze, often has bubbles within
it, but I don't think that these are what
cause pinholing. It's always seemed to me that
pinholing is caused by gases coming up from
the clay, not the gases trapped in the melt.
Another factor in pinholing is the inability
of that glaze to flow and cover the hole, and
without full-surround coverage of the gas
pocket, the reabsorption you refer to seems
unlikely to take place.
-Snail
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