History of drywall production

What is Drywall?  It is also known as plasterboard, wallboard, gypsum panel, sheet rock or gypsum board.  It is a type of panel made from calcium sulfate dihydrate (gypsum) and can include additives which is then pressed between sheets of thick paper.  It became more time effective to install than lath and plaster.  One of the great things about using drywall is that is very effective in a variety of situations.  It is a very effective sound barrier, can be installed and repaired at a lower cost than lath and plaster and can be used as an effective fire barrier. 
 
The first plaster board manufacturing plant was opened in Rochester, Kent, in 1888.  Another product was introduced in 1894 called the Sackett board.  It was made with plaster and multiple plies of wood felt paper.  In the early 1900’s the United States Gypsum Corporation bought the Sackett Plaster Board Company and introduced a product called Sheetrock in 1917. This product was applauded for its ease of installation.
 
(CaSO4•2H2O) is the chemical formula for gypsum.  As you can see it is 50% water by volume.  So, when Sheet rock panels are exposed to fire and high heat typically found in a home fire, heat is then absorbed as a portion of the combined water is converted to steam.  This process of calcination helps keep the opposite side of the gypsum panels cooler, as long as there is still any water left in the panel and the panel is still intact and not breached.  Alberta Fire Code can allow double drywall to be used in attic spaces as a fire barrier.