Linda Mosley on tue 30 apr 02
Dear Glaze Gurus of Clayart,
Here's a query that I could not find answered in the
archives:
We found that an unopened bag of Cornwall Stone, which
was stored in an unheated shed that freezes in winter,
feels damp and has big lumps. There is no apparent
leak in the roof and it was not sitting on the floor,
so it seems to have absorbed moisture from the air.
If we bring the bag indoors and dry it out, is it
still usable in the usual proportions of our glaze
formulae?
- Linda
=====
Linda Mosley
lindamosley@yahoo.com
ceramic instructor, St. Louis Community College - FV
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Jon Pacini on wed 1 may 02
Greetings All----
Linda Wrote-----We found that an unopened bag of Cornwall Stone, which
was stored in an unheated shed that freezes in winter,
feels damp and has big lumps----
The last couple of shipments of Cornwall stone that we have received
have been so wet they are nearly 20 % water!!! However when dried out and
lumps broken down, it has worked just fine for our production formulas.
If you try to use the material wet, and we have been succseesful with
that also, you need to account for the % of water weight. To do that, weigh
out 100 grms of wet Cornwall Stone, dry thoroughly and reweigh. The amount
less it weighs is the % of water. You'll need to add that much more
Cornwall stone per 100 grms used in your formula.
By the way, (no pun intended), the explanation we received to our
inquirery regarding the wetness was that the material is wet ground and
bagged in the woven plastic bags 'as is'. It's a very curious situation.
I've been using Cornwall Stone off and on for 30 yrs and have never seen it
this wet before.
Jon Pacini
Clay Manager
Laguna Clay Co
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