Drywall

Drywall

Drywall Drywall is a Construction Material consisting of thin Panels of Gypsum Board. The Board is composed of a layer of Gypsum Rock Sandwiched between two layers of special Paper. Drywall makes for a much more efficient method of Construction than the common earlier technique of applying wet plaster to a Gypsum lath.

Raw Materials: The primary component of Drywall is the mineral Gypsum. It is a light-density Rock found in plentiful deposits worldwide. Each molecule of Gypsum (or Dihydrous Calcium Sulfate) is composed of two Molecules of Water (H 2 0) and one of Calcium Sulfate (CaSO 4 ). By weight the compound is 21% Water, but by volume it is nearly 50% Water.
Water present in Gypsum is in Crystalline form: the Material is Dry. Although ice, another form of Crystalline Water, becomes a liquid at room temperature, the Water bound in the Gypsum Molecules remains solid unless it is heated to 212°F (100°C), at which point it changes to a gaseous state and evaporates.

Pulverized Gypsum is used for variety of applications: Gypsum, in its pure form it is white, but impurities often give it colors like Gray, Brown, Pink, or Black. Pulverized Gypsum is used for a wide variety of applications. It is an ingredient in some brands of Toothpaste and is used as a filler in products such as Paint, Cosmetics, and Drugs. Automotive window glass is secured in a bed of Gypsum while it is being Polished. Gypsum is applied to farmland as a Fertilizer and Soil conditioner.
The Manufacturing Process: Fabrication of Drywall consists of placing the Gypsum core Material between two layers of Paper, Drying the product, and finishing it into Panels of Standard size.

Blending of additives: Depending on the variety of WallBoard being Produced, Certain additives are Blended with the Plaster of Paris that will form the core of the Drywall. Each additional Ingredient amounts to less than onehalf of one percent of the amount of Gypsum Powder. Starch is added to help the Paper facings adhere to the core, and Paper Pulp is added to increase the core tensile strength. Unexpanded Vermiculite is added when producing fire resistant grades of Gypsum Board; in some cases clay is also added.
Drywall Making the Sandwich: The Gypsum Slurry is poured onto a layer of Paper that is unrolling onto a long Board machine. Another layer of Paper unrolls on top of the Slurry. The Sandwich then passes through a system of Rollers that compact the Gypsum core to the proper thickness. The most common thicknesses are 0.37 inch (9.5 mm), 0.5 inch (12.7 mm), and 0.62 inch (15.7 mm).

Finishing the Edges: Automated assembly lines in Gypsum Board plants range from 300-800 feet (93-247 m) long. As the Drywall continues along the Conveyor belt, the Edges are formed. Various shapes of Edges are possible, depending on the final use of the Panel. Options include the traditional square Edge, a tongue and groove type, tapered and/or beveled Edges, and even rounded Edges. The face Paper is wrapped snugly around each Edge and sealed to the back Paper.
Cutting the Panels: By the time the Edges have been shaped, the plaster core has set sufficiently for a knife to slice the continuous strip into standard Panel sizes. The Board, generally 48 inches (1219 mm) or 54 inches (1572 mm) wide, is usually cut into Panels that are 8 feet (2400 mm) or 12 feet (3600 mm) long.

The Drying process: The Panels are transferred to a Conveyor line that feeds them through a long, Drying oven. At one plant, for example, the gas-fired oven is 470 feet (143 m) long. Panels enter the oven at 500°F (260°C) and are exposed to gradually decreasing levels of heat during the 35-40 minutes they travel through the system. Humidity and temperature are carefully controlled in the Dryer.
The finished product: After emerging from the Drying oven, the Dry wall Panels are visually inspected before being bundled into "lifts" of 30 or 40 Boards and transferred to the Warehouse to await shipment. Each Board is labeled with a UPC bar code that is used for Warehouse inventory, billing, and price scanning at the retail level.

Product Evolution: Since the invention of Gypsum Board at the turn of the century, there has been gradual progress in making it lighter in weight while improving its performance characteristics. In the late 1950s, standard Gypsum Board (not fire-rated) weighed 2 pounds per square foot (9.8 kg per sq m); the various kinds of standard Gypsum Board now average about 1.6 pounds per square foot (8 kg per sq m). This not only makes handling and installation easier, but decreases shipping costs as well.


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