Jonathan Kaplan on sun 6 jan 08
I just have to weigh in on this one.
I think we need to kind of stop the "cheap potter"
concept..............
While I haven't been on the list for a while, I might like to add
that the idea of "making plaster good" by re-calcining it is quite
frankly just a waste of time and really bad information. Plaster is a
very cheap material to buy. IMHO it would be futile if not really
counter productive to try and re-constitute already cast plaster.
There are two types of water that we find in plaster. There is the
naturally occurring water in the gypsum chemistry that is taken to
the point of almost calcining in rotary kilns (heat is required, an
endothermic reaction). This renders the gypsum ready for use in
ceramic or other applications. We add water, the reaction is taken to
completion, heat is liberated (exothermic) and the plaster hardens.
The adding of water is the second water, the physical water.
Once the gypsum has gone through its change of state and change of
chemistry (alpha gypsum, beta gypsum) it cannot be made whole again
by calcining.
I would certainly not entertain this endeavor in any of my mold
making applications. Plaster is a very precise material and why
anyone would spend the time to try and reclaim plaster is just not
sound logic, especially when you can buy a bag of Potter #1 for under
$10.00.
I guess if you have too much time on your hands, are all dressed-up
with no place to go, then sally forth.......
Respectfully
Jonathan
Jonathan Kaplan
Ceramic Artist/Ceramic Designer
Master Mold and Model-Maker
Plinth Gallery/Ceramic Design
3520 Brighton Blvd
Denver, CO 80216
www.plinthgallery.com
www.jonathankaplanceramics.com
www.ceramicdesigngroup.net
NEW BLOG!!
http://siramic.blogspot.com
303 909-5488 cell
303 295-0717 office
303 296-3581 fax
Bruce Girrell on mon 7 jan 08
Jonathan Kaplan wrote:
> you can buy a bag of Potter #1 for under $10.00.
and then pay 50 bucks to have it shipped
For durable molds like you need Jonathan, there is no question that
calcining is very poor economy. But when I need a couple of drape molds and
all I have is a 3 year old bag of PP #1, I'm in the calcining group.
Bruce Girrell
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