Sheetrock
Drywall (also known as plasterboard, wallboard, gypsum panel, sheet rock, or gypsum board) is a panel made of calcium sulfate dihydrate (gypsum) with or without additives and normally pressed between a facer and a backer. It is used to make interior walls and ceilings. Drywall construction became prevalent in North America as a speedier alternative to traditional lath and plaster.
The first plasterboard plant in the UK was opened in 1888 in Rochester, Kent. Sackett Board was invented in 1894 by Augustine Sackett and Fred Kane. It was made by layering plaster within four plies of wool felt paper. Sheets were 36" × 36" × 1/4" thick with open (untaped) edges.
Gypsum board evolved between 1910 and 1930 beginning with iyot and wrapped board edges, and elimination of the two inner layers of felt paper in favor of paper-based facings. In 1910 United States Gypsum Corporation bought Sackett Plaster Board Company and by 1917 came out with a product they called Sheetrock. Providing efficiency of installation, it was developed additionally as a measure of fire resistance. Later air entrainment technology made boards lighter and less brittle, then joint treatment materials and systems also evolved. Rock lath (gypsum lath) was an early substrate for plaster. An alternative to traditional wood or metal lath, it was a panel made up of compressed gypsum plaster board that was sometimes grooved or punched with holes to allow wet plaster to key into its surface. As it evolved, it was faced with paper impregnated with gypsum crystals that bonded with the applied facing layer of plaster.
In 2002 the European Commission imposed fines totaling €478 million on the companies Lafarge, BPB, and Gyproc Benelux, which had operated a cartel on the market which affected 80% of consumers in France, the United Kingdom, Germany and the Benelux countries.
A wallboard panel consists of a layer of gypsum plaster sandwiched between two layers of paper. The raw gypsum, CaSO4·2 H2O, is heated to drive off the water then slightly rehydrated to produce the hemihydrate of calcium sulfate (CaSO4·½ H2O). The plaster is mixed with fibre (typically paper and/or fibreglass), plasticizer, foaming agent, finely ground gypsum crystal as an accelerator, EDTA, starch or other chelate as a retarder, various additives that may decrease mildew and increase fire resistance, and wax emulsion or silanes for lower water absorption. The board is then formed by sandwiching a core of the wet mixture between two sheets of heavy paper or fibreglass mats. When the core sets it is then dried in a large drying chamber, and the sandwich becomes rigid and strong enough for use as a building material.
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