Craig Martell on sat 6 dec 97
Hi:
In my post on the Wild Rose glaze shivering, I incorrectly stated that
lithium has "almost no coefficient of expansion". Lawrence and West in
"Ceramic Science for the Potter" state that lithium has an "abnormally low
coefficient of expansion", but nowhere, do they state that it is almost
zero. No one else says this either, unless we are talking about Eucryptite,
that has a NEGATIVE coefficient of expansion. Relax, nobody uses
Eucryptite! Actually, magnesium, boron, and possibly zinc, have lower
expansion rates than lithium.
My feeling now is that lithium causes shivering problems in glazes more than
the other low expansion oxides because it is such a light metal that
percentage weights in glazes contribute a lot of lithium on the molecular
level and this huge supply of lithium molecules really lowers the
coefficient of expansion in glazes.
Thanks to David Hewitt for pointing out the error and if I'm incorrect here
as well, lemme know.
gotta go to the library, Craig Martell-Oregon
| |
|
