Making Plaster Bats best plaster to use
Posted 03 October 2011 - 07:04 PM
There is #1 potter's plaster, which is used for making slip molds. It is more expensive than regular plaster of paris, which I can get for 8 bucks per 25# bag at Home Despot, but it will absorb more water and withstand repeated wetting. You can find it online, or ask at an art supply store. One good sized bat will use a lot of plaster. I've mostly made bats for wedging on, and they weigh about 20 pounds. Weigh one of the ones you use now to get an idea of how much plaster you will need.
Posted 03 October 2011 - 08:34 PM
If this is your first time using plaster and making plaster casts get a good book on how to make them. Try-
'Mold Making for Ceramics' by Donald E. Frith or do a library search for other books. Don't just dive in without some information on how to use the material.
Posted 04 October 2011 - 06:38 AM
can supply you with the correct information on measuring and mixing .
Posted 05 October 2011 - 06:10 PM
Read (per Lucille's post) about working with and mixing plaster before starting. Try to be gentle during the mixing so there are fewer air bubbles. Use a separator (liquid soap works well) on the Formica and the springform bands; let dry before pouring the plaster into the form. Tap the table or the Formica to make any air bubbles rise to the top. As the plaster cures, it gives off heat so when the surface solidifies release the latches because plaster expands as it cures and hardens.
You will probably have to do some clean-up on the bats (round the edges so they aren't easily broken)--I use a Stanley SurForm tool. I used my wheel and Giffin Grip to keep it round.
Most importantly: The clay you use around the base should either be kept in a sealed bucket clearly marked FOR PLASTER USE ONLY or tossed in the garbage. Thoroughly vacuum and wipe down your wheel and surrounding area to make sure you don't have plaster particles that could accidently get into your studio clay/work.
If you are making drying bats . . .that's a whole nother story.