Whether gypsum plaster is moisture preserving?

Calcined gypsum is capable of reacting with water to form calcium sulfate dihydrate which is a fairly hard and rigid product and which is referred to herein as "Gypsum Plaster."

A number of plasters are used in plastering, among them gypsum plaster offers better advantages, in terms of smooth finish coat, strength, curing time, good insulation, shrinkage crack resistant, light weight and resistant to fire.

An example of a common gypsum product is gypsum board, which is widely used as a structural building panel. Speaking generally, gypsum board comprises a core made from an aqueous slurry of calcined gypsum which hydrates to form set gypsum. Typically, the board has a a paper sheet lining adhered to both of its faces. A characteristic of gypsum is that it has a tendency to absorb water. To illustrate, a gypsum core containing no water-resistant additives can absorb as much as 40 to 50 wt. % water when immersed therein at a temperature, of 70° F for about two hours. In applications where the gypsum product is exposed to water or high humidity, this characteristic is undesirable. The absorption of water by the gypsum tends to reduce the strength of the product to render the product vulnerable to microbiological growth, and to cause the facings to delaminate.

Recent invention relates to a method of making moisture resistant gypsum-based products, e.g., gypsum boards, reinforced gypsum composite boards, plasters, machinable materials, joint treatment materials, and acoustical tiles, by adding to the aqueous slurry used to make the gypsum-based product a small amount of a siloxane and a catalyst to enhance the curing of the siloxane. The method comprises mixing a siloxane emulsion with the gauging water used to prepare said gypsum-based article; mixing a dead burned magnesium oxide catalyst with calcined gypsum; mixing the silicone/water mixture with the gypsum/magnesium oxide mixture to form an aqueous slurry; and shaping the slurry into the desired shape and allowing said shaped slurry to set to form a set gypsum-based, water-resistant article.

One of the common causes of defects in buildings is the presence of water. Dampness can itself be a defect and it can be the cause of other defects. There is also epidemiological evidence from studies on indoor air quality as noted by the World Health Organization (WHO) to show that people living in damp or mold-ridden buildings are at an increased risk of respiratory disorders (WHO 2009).

In-general gypsum is moisture preserving, but when compared to cement plaster which is commonly used, gypsum plaster can give the same performance of cement plaster. Its advisable to use gypsum plaster (without any admixtures) for interior plastering of walls where there are no consistent presence of liquids. A running water body will not affect the gypsum plaster, stagnant water for more than 2 days can spoil the gypsum plaster.

Hence gypsum plaster is advisable for interior plastering of public, semi-public and selected private areas of a building, under expert guidance. This way one can save environment since gypsum plaster is an ecofriendly and also save the hard-earned money.

Gypsum by nature has a physical property of high cooling factor, because of the percentage of water and the chemical composition of the salt that is naturally occurring as a raw material. 

One of the best advantages of gypsum plaster, that impress a common man is, the touch and feel factor. One will be mesmerized to see the finish and feel the difference once he/she touches the gypsum plastered surface. The temperature of the surface will be cool enough that one will say, this is AWSOME!