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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 ...
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
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.
It is chiefly made of plaster of Paris (powdered gypsum), with a little cement, glycerin, and dextrin, mixed with water until it is about as thick as molasses. When staff is cast in molds, it can form any shape. To strengthen it, coarse cloth or bagging, or fibers of hemp or jute, are put into the molds before casting. It becomes hard enough in ...
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]
Acidic drain cleaners usually contain sulfuric acid at a high concentration which turns a piece of pH paper red and chars it instantly. Apart from grease and hair, an acidic drain cleaner containing sulfuric acid can be also used to dissolve tissue paper inside water pipes. Acidic drain cleaners usually contain sulfuric acid at high ...
Gypsum mortar, also called plaster of Paris, was used in the construction of many ancient structures. It is made from gypsum, which requires a lower firing temperature. It is therefore easier to make than lime mortar and sets up much faster, which may be a reason it was used as the typical mortar in ancient, brick arch and vault construction.
Depending on the setting time of the plaster. once the moisture of the plaster starts to be drawn by the board a second pass is made. this is called knocking down. it is much like applying paint with a roller in wrist action and purpose. to smooth out any lines and fill in any major voids that will make extra work once the plaster starts to ...