iandol on sun 21 apr 02
Dear Carol,
Am I reading your posting correctly. You say you are buying Ground =
Gypsum by the bag at $3:00 50 lbs
I think you are buying the raw mineral.
It has to be processed to convert it into Potters Plaster.
This involves having it heated to about 120 degrees Celsius to remove =
part of the water of crystallisation. This converts it into the =
Hemi-Hydrate. You do not remove all of the water which converts it into =
Anhydrite.
The only other time this may happen is if a parcel of Potters Plaster =
(or Plaster of Paris) has become stale due to exposure to the atmosphere =
so that water is adsorbed.
I would check it out and find out if it is "As Mined"
Hope this solves your problems.
Best regards,
Ivor.
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