DEFINITION. Gypsum (calcium sulphate dihydrate) is a naturally occurring mineral used in dentistry to fabricate models (Figure 12.1a), casts and dies (Figure 12.1b). Calcination is the process of heating the gypsum to dehydrate it (partially or completely) to form calcium sulphate hemihydrate.


Is Gypsum dangerous? Gypsum products are not classified as dangerous according to EU CLP Regulations. There are no long term adverse medical effects from ingestion of gypsum. If ingested, wash out the mouth and drink plenty of water. Plaster powders/dust potentially may irritate eyes or sensitive skin or irritate the respiratory system.

what are gypsum products?

Three types of gypsum products will be discussed: plaster, stone, and high-strength or improved stone.

What is another name for gypsum? Alabaster. Fine-grained, slightly colored. Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard/sidewalk chalk, and drywall.

why are gypsum products vibrated?

Use of Gypsum Products in Dentistry. – Gypsum products are supplied as fine powders that are mixed with water to form a fluid mass that can be poured and shaped and that subsequently hardens into a rigid, stable mass. – Gypsum products are used mainly for positive reproductions or replicas of oral structures.

How Gypsum is formed? It forms in lagoons where ocean waters high in calcium and sulfate content can slowly evaporate and be regularly replenished with new sources of water. The result is the accumulation of large beds of sedimentary gypsum. Gypsum is commonly associated with rock salt and sulfur deposits.

what are the types of gypsum?

The major types of Gypsum products that are available are, Type I — Impression Plaster. Type II — Dental Plaster. Type III — Dental Stone Type IV — Improved Dental Stone or Die stone or High Strength Stone. Type V — Dental Stone, High Strength, High Expansion.

Where does gypsum come from? Chemically, gypsum rock is calcium sulfate with two molecules of water. Gypsum rock is found throughout the world and deposits in North America run from Baja, Mexico, through Utah and from southwestern Texas to the Niagara River in New York State.

What is gypsum used for?

Gypsum uses include: manufacture of wallboard, cement, plaster of Paris, soil conditioning, a hardening retarder in portland cement. Varieties of gypsum known as "satin spar" and "alabaster" are used for a variety of ornamental purposes; however, their low hardness limits their durability.

How do you identify Gypsum? Gypsum is a very soft mineral that is easily identified by its hardness, cleavage, and solubility in water. Typically clear to white, gypsum may be colored reddish to brown or yellow if impurities are present.

Why gypsum is added in cement?

Gypsum is a mineral and is hydrated calcium sulfate in chemical form. Gypsum plays a very important role in controlling the rate of hardening of the cement. During the cement manufacturing process, upon the cooling of clinker, a small amount of gypsum is introduced during the final grinding process.

How is synthetic gypsum made?

Synthetic gypsum is one of the by products of “clean coal” technologies. Synthetic gypsum is formed through a process called flue gas desulfurization or FGD. A slurry of powdered limestone and water is sprayed in the flue gasses emitted from the boilers of a coal fire plant.

Is gypsum hygroscopic?

Except crystallization water, gypsum has hygroscopic moisture that is on the surface of gypsum rock and in its pores. Crystal gypsum in monoclinic system, crystals are plate-like, columnar, needle-shaped and fibrous.

How is gypsum made from limestone?

Gypsum is a naturally occurring stone, a metallic salt of calcium. It commonly forms as an evaporite from the dissolution of limestone by exposure to sulphuric acid from volcanic activity. Under certain conditions, continual cycles of dissolution and evaporation will agglomerate into a “primary” deposit of gypsum.

What does Gypsum do to soil?

Gypsum is calcium sulfate, a naturally occurring mineral. It has been touted as beneficial for breaking up compact soil, especially clay soil. It is useful in changing the soil structure of excessively heavy soils which have been impacted by heavy traffic, flooding, overcropping, or simply overly weatherized.

Is gypsum used in toothpaste?

Gypsum is used in toothpastes, shampoos, and hair products, mainly due to its binding and thickening properties. Calcium sulfate acts as a coagulator in making tofu. It is also used in baking, mainly as a dough conditioner.

What are the characteristics of gypsum?

PHYSICAL CHARACTERISTICS: Color is usually white, colorless or gray, but can also be shades of red, brown and yellow. Luster is vitreous to pearly especially on cleavage surfaces. Transparency crystals are transparent to translucent. Crystal System is monoclinic; 2/m.

How many types of gypsum boards are there?

Four Types of Gypsum Plaster Boards and their Thermophysical Properties Under Fire Condition Karim Ghazi Wakili. E. Hugi.

How long does gypsum take to dry?

It takes not just effort but also plenty of time, particularly when it comes to drying time for each coat of drywall mud. Drywall mud, also known as joint compound, needs to dry for 24 hours between each coat and before sanding, priming, and painting.