Final answer:
The statement that plaster casts become rigid within a few minutes is false. It takes about 24 to 72 hours for plaster casts to fully dry and harden.
Step-by-step explanation:
The statement that plaster casts become rigid within a few minutes after they are put on is false. Plaster casts are made from a type of plaster bandage cloth that consists of a cotton bandage that has been combined with plaster of Paris, which is a white powder. When the bandage is soaked in water, the powder becomes a paste that eventually hardens.
However, it typically takes about 24 to 72 hours for a plaster cast to fully dry and become rigid. Immediately after application, the cast will be soft and moldable. Extra care should be taken during the initial hours after application to prevent the soft cast from being dented or damaged, as it has not yet reached its full strength.