Practice question · Select all that apply
Why is plaster sifted into water and left to stand before mixing? Select every true statement about the procedure.
Hints
- Three describe correct procedure and its reason; one is a convenient belief.
- Water content determines the strength of the set plaster.
Show the answer
- A. Plaster is sifted into water rather than water poured onto plaster
- B. Adding extra water produces a weaker, more porous set
- C. It is left to slake for a couple of minutes before mixing
Why
The fourth is the tempting mistake. Extra water does not buy working time for free, it produces plaster that is weaker and more porous, which for a mould means a face that degrades faster and a shell that breaks in handling.
Practise Moulds II: Materials and Procedure
The app has 5 more questions on this lesson, and keeps your place in the course. Sculpture I is free to start.
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