stephani stephenson on wed 21 feb 07
I have always had a hesitancy with glass pools,
melted globs of glass in clay because of the
annealing issue. It is great fun and easy eye candy,
but outside of personal experimentation.....
bot , i have never trusted it.
glass needs to be annealed. otherwise...when it is
cooled too quickly and at the wrong rate...
it might look just fine, but the glass is under a
huge amount of stress and can 'check' at any time,
whether that is in five minutes, five months or five
years. blown glass that seems fine, when not annealed
properly can sit on a shelf for years, then when a
garbage truck rolls down the road, it can develop a
major ,spiral crack , etc....
in the glassblowing department they use to make these
things called 'Job's Tears" by dropping small globs
of molten glass into a bucket of water. the resulting
glass marbles looked fine . you could hold them in
your hand, but when subject to jolting, they
disintegrated.....
i don't know what the limits are when the glass is
over clay. if there is a point where the glass is thin
enough and interacting with the clay body enough so
that it will be crazed, but stable enough, bound
enough.
basically glazes are glass but we add materials such
as alumina to get them to fit the clay, stay on the
clay..... for good reason.
because of the annealing issue, the differentiation
in coefficient of expansion and contraction on
cooling, i remain leery about glass in clay,
especially when sold commercially.
Stephani Stephenson
____________________________________________________________________________________
Any questions? Get answers on any topic at www.Answers.yahoo.com. Try it now.
Marcia Selsor on wed 21 feb 07
Good point Stephani,
I had a student melt some glass, a lot of glass, in a ^9 pot.
He had about a inch of glass melted in the bottom of his pot. Within
a few days the whole things fractured.
-with a lot of umph!
Marcia Selsor
http://marciaselsor.com
| |
|
