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Making Plaster Bats


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#1 bluedawg

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Posted 03 October 2011 - 06:56 PM

Is there a certain type of plaster that is best to use for making plaster bats? Is there an artists grade plaster?

#2 BeckyH

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Posted 03 October 2011 - 07:04 PM

Is there a certain type of plaster that is best to use for making plaster bats? Is there an artists grade plaster?

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.

#3 Lucille Oka

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Posted 03 October 2011 - 08:34 PM

Check with your ceramic supplier for available plaster choices. There are many different types of plaster for a variety jobs. If you want to really find out about plaster go to-http://www.usg.com/i...l/ceramics.html You can spend a lot of time on the site but you will learn a lot. Pay attention to how to mix and how to dry the plaster casts.
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.


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#4 Marcia Selsor

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Posted 04 October 2011 - 06:38 AM

#1 Pottery plaster is rated as one of the softer of most casting plasters. Hydrocal is much harder and more expensive. You will need to order it from a ceramic supply. You need to determine what you want in your bats.
U.S Gypsum
can supply you with the correct information on measuring and mixing .
http://www.usg.com/i...l/ceramics.html

Marcia

#5 Idaho Potter

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Posted 05 October 2011 - 06:10 PM

Way back in 1985 I made plaster throwing bats with industrial plaster and I use them even today. I used springform cake pans (NOT the bottoms, only the sides) for forming the bats--. Using a Formica sink cut-out for a base, the springform rings (latches closed) become your cottle "boards" once you have put a perimeter of clay around the bottom to seal against leaks. Make sure the table you are working on is level--very level.

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.




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