I love plaster and have used it for 3 different kids of art projects.
1 Plaster in a baggie as part of a prehistoric "rock" carving idea;
head's up on this:
I had intended the students to form a "rock" that might suggest an
animal or figure which they would later "carve details into. I had
pre-measured amounts so I knew exactly how much industrial plaster,
water and sand (or vermiculite if you wish) each student would need
to scoop into their baggie. I had materials arranged in an assembly
line, so the process of providing materials to a class of 34 grade
10's would proceed smoothly.
However, you must teach proper mixing. It is important to measure
accurately and mix the ingredients together well, smooshing the lumps
out of the dry ingredients before adding the water, which is contrary
to how you should mix plaster (you should add plaster to water, not
vv). I found that all but a few students overmixed, and instead of
forming a "stone", turned their mixtures to a rubble (these grade
tens were NOT sensitive at all to their ingredients - showed few
aesthetic brains). Make sure they understand that once they have
their water and plaster mixed, they are to immediately palm the
mixture & pack it into a shape. The transformation happens within 3
-4 minutes if they have properly measured their ingredients.
Once they knew what to do they were fine but they were bozos at first.
2 low relief carving making a portion of an egyptian tomb wall - well
received by students, and I prepared the plaster tablets by pre
forming them in a plastic lined cookie sheet, and cutting each sheet
of plaster into 6 - 8 rectangles when "just set". Make sure you pour
it about a half inch thick.
3 sculpture in the round for Art 11, casting the plaster in cardboard
milk containers. Our tools include 6" lengths of wire coat hanger
bent to the letter "P" shape with the tip ground to a chisel point,
hack saw blades snapped in two, pieces of smashed grinding stone for
rasping, and whatever else the students ca bring to school.