eden@sover.net on thu 6 aug 98
Just thought I'd post this again in case it might be useful.
>Date: Wed, 27 Sep 1995 23:29:35 -0400 (EDT)
>From: Eleanora Eden
>To: Ceramic Arts Discussion List
>Subject: plaster mold making >X-Status: >
>Hi All, >
>Seems it's time for me to repost Eleanora's EZ Breasy Plaster Casting
Method. Having no patience at all with the weighing of water I do it in
>the following manner: >
1. Judge volume of pour (if you keep a log of your pours it will help). > >
2. Volume of plaster desired = volume of dry plaster. Only FRESH #1
>pottery plaster should be used. Know your source. Ask how long the bags
>have been around. >
>3. Volume of water = 2/3 volume of dry plaster. >
>so. measure your water and pour it in a container large enough. Dump
>plaster in and mix for afew minutes. When it's thickened like cream it's
>ready. When it's thickened like pudding it's more than ready. >
>This is not to say that I don't think people should bother to learn more
>than this about plaster. But this works fine for me >and I make alot of
molds. > >
Eleanora
..............
Eleanora Eden 802 869-2003
Paradise Hill
Bellows Falls, VT 05101 eden@sover.net
"Never look down on anybody unless you're offering them a hand to help them
up."
Pete Hamill's mom
Lorca Beebe on fri 7 aug 98
No. 1 Plaster should be used only for slip casting, if you casting sculpture
for press molds its more economical to use casting plaster and its a little
long lasting, Plaster of Paris usually comes in small packages and I find it
to expensive.
There is a very technical way to calculate the amount of plaster and water,
basically by measuring the volume and area of the piece to be cast, the ratio
of water to plaster is crucial in creatin a mold for slip casting , and god
knows where I have that formula now, but I'm sure you can look it up in a book
somewhere...
Use a generous amount of Vaseline or mold release soap on the piece, check for
under cuts, if you look from a birds eye view the piece should appear flat.
Slowly pour the plaster into the water, keep doing this until you see
"islands" forming in the bucket, these are little mounds of plaster...tap the
bucket against the floor a couple of time to force air bubbles to come to the
surface, wait about 5 minutes, mix I use a jiffy mixer and rinse it right
away. splater a layer of plaster unto piece, if this is a funky sculptural
press mold, have some pieces of burlap cut up to dip in plaster an put on
second or third layer, if your container walls are strong you can pour the
whole thing at once, other wise the pour in layers like a lasagna, if the mold
is intendended for slip casting you can spray or brush on alcohol to pop all
the air bubbles.
For the second part use a spoon or quarter and dig in the side of the mold in
a circular motion creating a sorta dimple, this is the "key", make sure you
put on a generous amount of vaseline or mold release, and repeat process, if
this is a many part mold, then you can insert triangular aluminum keys on the
side to help separate mold later. Insert a tringular aluminum key ( dont make
a sharp point) and tap it gently with a mallet, do this all around seem until
mold separates. Clean up mold with a dry wall rasp or plane.
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