got through a few more sculptures today- 13 to be exact. next week we’ll finish them off and get them painted black so the kids can apply the metallic patinas. this week i let some of the kids mix their own plaster which they enjoyed. they were trying to understand the difference between “drying” and “setting up” and why the plaster heats up as it hardens ……
When mixed with water, calcium sulphate hemihydrate, CaSO4·21H2O, also known as Plaster of Paris, undergoes an exothermic hydration reaction :
CaSO4·21H2O + 23H2O → CaSO4·2H2O
So basically, the hydration process throws off energy in the form of heat.
I have spent many years mixing plaster in my mold shop when running my porcelain studio and it was fun to see the kids enjoy it so much- just look at the smile-
here they are getting ready to mix the next batch
a rinsing bucket so none of the plaster goes down the drain and clogs it up….ask me how i know.
sprinkle the plaster evenly over the surface of the water until little islands appear on top breaking the surface of the water.
they would have enjoyed just mixing plaster and nothing more!
overheard while working:
“i’ve never gotten dirty before!” (yikes!)
“oooh, i like the way it feels on my hands!”
“art is hard to talk about”
i swear, i’m gonna bring in a recorder soon and post some audio of what these kids say during art. it’s very revealing sometimes!