I would call a local ceramic shop (the one that pours and sells molds) and use the type of plaster they use for your wedging table and bats. That is what I did and I was able to get a bag of 100 lbs. of plaster for $25's. If you get it at Home Depot or Lowes it will cost more.
In the book Handbuilt Ceramic by Kathy Triplett there is a Plaster and Water Ratio chart on page 147. For example 25 lbs of plaster will take about 18 lbs of water. This isn't how I mix my plaster and if you would like an explanation email back and I will go into more detail.
The way I made my bats was to pour plaster into rectangle plastic tubs after spraying WD 40 on the walls and bottom, the kind with the folding lids. My bats are about 12 inches by 18 inches and 2 1/2 inches thick. They can be heavy so I only get them out if all the students are learning to wedge and I need the extra plaster surface or I need to reclaim a lot of clay.
As far a "How do I translate cubic inches to pounds of
plaster or to pints of water?" I have no idea but I would just mix up more then I need and pour the rest into tubs or paper milk cartons for white cubes or oatmeal containers for cylinders, to use in still life or carving.
Hope this helps.
----- Original Message -----
From: Jeannie Hess
Sent: Saturday, August 23, 2003 8:44 AM
To: ArtsEdNet Talk
Subject: Plaster and plaster bats?
What type of plaster should I get to fill my clay wedging table? How do I
figure out how much to order? Where can I order this stuff? The local
I've been pouring over clay and pottery books at Borders, but the plaster
info is how to make molds.
The wedging table is almost ready. Also, I would like to make a big
rectangular bat so that I can reclaim my clay. I know how to make the
frame for the bat, but what kind of plaster do I use?