Drywall is made primarily of gypsum. Gypsum is a mineral usually found in massive beds that look like white sand, though impurities can cause beds to appear pink, yellow or gray. One of the most famous gypsum beds in the United States is the popular White Sands National Monument in New Mexico.
Despite being used to make drywall, there's a large amount of water in gypsum. The water is in crystalline form, which is why the individual molecules of gypsum are dry. These crystalline water molecules give finished drywall its fire-resistance. As drywall gets hot, the water crystals begin to destabilize and begin vaporizing as the water reaches its boiling point. The evaporating water crystals keep the drywall cool, protecting the structure behind it.
Once gypsum has been mined, it's transported to factories throughout the world. There, raw gypsum is mixed with several additives, including starch, paper pulp and an emulsifier (or thickening agent), then blended with water to form a thick paste. The gypsum paste is spread onto Manila paper in 3/8-inch to 3/4-inch-thick layers. Another sheet of Manila paper is then laid on top. The entire formation passes through ovens that heat the sheet at temperatures up to 500 degrees Fahrenheit. This dries the material out and prepares it for cutting. Typical sheets are 4x8 feet, though 4x10 feet and 4x12 feet sheets have become popular recently, as they allow for faster installation of taller walls.
Additional additives or types of paper are used when creating more specialized forms of drywall. For more on this, and information on finding the right type of drywall to suit your needs, read on to the next section.