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Cement mortar can be chiselled away with a hammer and chisel gradually. Plaster is easily removed through mechanical methods such as chiselling and chipping away with sharp implements. Saws, drills, and other mechanical methods can be used to remove the bulk of protruding materials; however, scratches, chips, and breaks can occur. [4]: p.77–78
The word gypsum is derived from the Greek word γύψος (gypsos), "plaster". [9] Because the quarries of the Montmartre district of Paris have long furnished burnt gypsum (calcined gypsum) used for various purposes, this dehydrated gypsum became known as plaster of Paris. Upon adding water, after a few dozen minutes, plaster of Paris becomes ...
A gypsum block is made of gypsum plaster and water. The manufacturing process [1] is automated at production plants where raw gypsum (CaSO 4 ·2H 2 O) is ground and dried, then heated to remove three-quarters of the bound water and thus transformed into calcium sulfate hemihydrate (CaSO 4 ·½H 2 O), also known as gypsum plaster, stucco, calcined gypsum or plaster of Paris.
With judicious heating, gypsum converts to the partially dehydrated mineral called bassanite or plaster of Paris. This material has the formula CaSO 4 ·( n H 2 O), where 0.5 ≤ n ≤ 0.8. [ 8 ] Temperatures between 100 and 150 °C (212–302 °F) are required to drive off the water within its structure.
Stucco plaster reliefs, such as this work at the Château de Fontainebleau, were hugely influential in Northern Mannerism. A plaster low-relief decorative frieze is above it. Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. [1]
The plaster sets, usually in about 15 minutes, and the pattern is removed. The mold is then baked, between 120 °C (248 °F) and 260 °C (500 °F), to remove any excess water. The dried mold is then assembled, preheated, and the metal poured. Finally, after the metal has solidified, the plaster is broken from the cast part.
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He noted that gypsum plaster (plaster of Paris) was moulded around the patient's leg to cause immobilization. If the cast became loose due to atrophy or a reduction in swelling, then additional gypsum plaster was added to fill the space. Adapting the use of plaster of Paris for use in hospitals, however, took some time.