Bill Merrill on sun 16 aug 09
Can't remember if I sent this out or not
________________________________
Jeremy
=3D20
For every 80 cubic inches of finished plaster you need ..(.example 8" x =3D
10" x 1" =3D3D 80 cubic inches )
1 quart of water and 2 3/4 pounds of plaster. If you want a harder =3D
denser plaster mix use 3 pounds of plaster for every quart of water. I =3D
use # 1 potters plaster.
=3D20
Put your water in your mixing bucket. Use lukewarm water. Cold water =3D
retards the setting time, hot water is not reccommended as there is no =3D
working time. Add the plaster by sifting the plaster into the water =3D
with your hand until the plaster is absorbed into the water. DO NOT =3D
STIR for several minutes. Give the plaster a chance to absorb the =3D
water. Stir the plaster by adjatating your hand undder the surface of =3D
the mix. The plaster will become throughly mixed this way. The =3D
stirring will start the mix to go through it's chemical change. Tap the =3D
bucket up and down to get rid of air bubbles, they will come to the =3D
surface. Drag your finger across the mix. If the mix peaks a little =3D
without settling down totally , this is a good time to pour. Pouring =3D
too thin will allow the plaster/water mix to potentially to run out of =3D
seams in your mold. Don't forget to put a mold release on the walls of =3D
your form so the plaster will release. If building a flat angled mold I =
=3D
use Melamine, a product that has a formica like surface on one side. =3D
The plaster comes off easily.When the plaster starts going through the =3D
heating stage of setting up, wait a few minutes and release The screws, =3D
rubberbands whatever is holding the form together. Thyis will keep the =3D
pold from developing any cracks at joints due to expansion of plaster =3D
when going through the hardening stage. During the heat stage the =3D
plaster is weak and the mold shoul not be taken off for at least 20 =3D
minutes,
=3D20
Make a batch large enough to make 1 pour. I have several 30" by 30" x =3D
3" wedging areas.
=3D20
30" x 30" x 3" =3D3D 2700 2700 divided by 80 =3D3D33.75 quarts of water.=
=3D
2.75 lbs plaster X 33.75 Qts ofwater + 92.8 pounds of plaster.
=3D20
If you have not poured plaster before this amount is not advise without =
=3D
help. Make a 4" x 4" x 4" open cube. use mold release and figure your =
=3D
plaster and water amounts. Pour the form. When the plaster use =3D
something like a metal straight edge to take off any extra paster. =3D20
=3D20
If making a wedging table, use Melamine so the bottom of the mold is =3D
perfectly smooth. =3D20
=3D20
Bill
Bill Merrill on fri 15 jan 10
I'm not listing much on Clayart anymore, but I sent this to a friend of
mine and saw that there might a few people that would benefit from
forwarding what I wrote about making a good wedging surface. =3D20
=3D20
For every 80 cubic inches of finished plaster you need ..(.example 8" x
10" x 1" =3D3D 80 cubic inches )
1 quart of water and 2 3/4 pounds of plaster. If you want a harder
denser plaster mix use 3 pounds of plaster for every quart of water. I
use # 1 potters plaster.
=3D20
Put your water in your mixing bucket. Use lukewarm water. Cold water
retards the setting time, hot water is not reccommended as there is no
working time. Add the plaster by sifting the plaster into the water
with your hand until the plaster is absorbed into the water. DO NOT
STIR for several minutes. Give the plaster a chance to absorb the
water. Stir the plaster by adjatating your hand undder the surface of
the mix. Plaster will not set up until you start stirring the mix. The
plaster will become throughly mixed this way. The stirring will start
the mix to go through it's chemical change. Tap the bucket up and down
to get rid of air bubbles, they will come to the surface. Drag your
finger across the mix. If the mix peaks a little without settling down
totally , this is a good time to pour. Pouring too thin will allow the
plaster/water mix to potentially to run out of seams in your mold.
Don't forget to put a mold release on the walls of your form so the
plaster will release. If building a flat angled mold I use Melamine, a
product that has a formica like surface on one side. The plaster comes
off easily.When the plaster starts going through the heating stage of
setting up, wait a few minutes and release The screws, rubberbands
whatever is holding the form together. This will keep the pold from
developing any cracks at joints due to expansion of plaster when going
through the hardening stage. During the heat stage the plaster is weak
and the mold shoul not be taken off for at least 20 minutes, If the form
is put together with screws loosen them when the plaster starts going
through the heating process.
=3D20
Make a batch large enough to make 1 pour. I have several 30" by 30" x
3" wedging areas.
=3D20
30" x 30" x 3" =3D3D 2700 2700 divided by 80 =3D3D33.75 quarts of water.
2.75 lbs plaster X 33.75 Qts ofwater + 92.8 pounds of plaster.
=3D20
If you have not poured plaster before this amount is not advisable
without help. Make a 4" x 4" x 4" open cube. use mold release and
figure your plaster and water amounts. Pour the form. When the plaster
is stiffer use something like a metal straight edge to take off any
extra plaster from the top, which is really the bottom as the melamine
will give a glass like surface to the plaster.
=3D20
If making a wedging table, use Melamine so the bottom of the mold is
perfectly smooth. This is then used as the top for wedging. =3D20
=3D20
Bill
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