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Re: [teacherartexchange] Plaster Sculpture - -wet or dry???


From: Marvin Bartel (marvinpb_at_TeacherArtExchange)
Date: Fri Mar 28 2008 - 11:15:06 PDT

>With warm weather approaching and a class of middle schoolers with spring
>fever, I am thinking about doing some plaster sculpture. I think I will
>introduce "public art" and have the kids design a "site specific" plaster
>sculpture. I thought we could go outdoors to do most of the carving, thus eliminating
>much of the mess.
>Question - - - is best to allow the plaster to dry out before sculpting
>begins? Or should we keep the plaster damp by storing it in a baggie? I am
>thinking through the process and just wonder how long the plaster should dry, or
>if it should dry, after removing it from the form before carving begins.

If you keep plaster wet or soak it as working it will create less dust and may be a bit easier to carve. Good quality pure plaster may be quite hard for middle school children to carve once it has set, even if it is kept wet.

Other options include mixing it with other materials in various proportions to make it easier to carve. Mixing it with too much water also makes it less hard to carve, but easier to break. The general rule for making good plaster is to drop it into clear water without stirring until it now longer sinks and there is not water on top. No stirring until all the plaster is added. Stir until smooth. Bump or vibrate to get air bubble to come to top. Wash nothing down any drains, but discard all extra in trash and pour wash water outside because it sets up in drain pipes, gradually blocking them closed.

Other additives that can be mixed with plaster to give it color, texture, and less hardness are virtually limitless. They include things like Styrofoam beads, screed dirt, sand, potting vermiculate, temper paint, etc. Adding Portland cement makes plaster much harder and stronger.

I would probably have couple of trustworthy students try some experimental mixes before doing this with the whole class. When it is too hard they may make sculpture that still looks like the original block. When it is too soft it breaks too easily.

Our sculpture teacher has students carve blocks of Styrofoam and then coat them with a few coats of thick drywall texture stuff available from builders supply places. The Styrofoam gets everywhere when they are carving, but it is easy to carve with rasps. The finished coated pieces are quite durable and very light weight.

Marvin Bartel, Ed.D., Professor of Art Emeritus
Goshen College, 1700 South Main, Goshen IN 46526
studio phone: 574-533-0171
"Art is me when I am myself." ... a kindergarten girl when asked, "What is art?"
"You can't never know how to do it before you never did it before." ... a kindergarten boy working with clay for the first time.

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