![]() ![]() Absorption from that of a rigid sponge to an impervious surface that sheds water.Strength and hardness from the weakest chalk to four times greater than concrete. ![]() Setting time from 3 minutes to 20 hours.Expansion from close to zero to 3/16 inch per foot.Homogeneity with no grain, hard or soft spots.As a semi-moist powder pressed between dies.Worked in a plastic state by screeding, template forming or paddling.Mixed as a fluid slurry, it can be cast or sprayed.The general characteristics of plasters are: Each step is critical to achieving the desired end product. This is a very complex process with many variables affecting the outcome from the grinding and calcination process to the reintroduction of water. With the reintroduction of water to any plaster, a new interlocking structure of needle-like crystals forms. of plaster to make a workable slurry whereas gypsum cements require 22-45 lbs. The term "gypsum cement" refers to harder and higher strength plasters manufactured by using heat and pressure. ![]() The manufacturer controls the process to achieve different size and shape crystals which then results in different final characteristics. The calcination process is one of heating the finely ground material which removes the chemically-bound water which then results in a different independent crystallline structure. The gypsum is finely ground and the chemically-bound water is then removed through one of two calcination processes depending upon the type of plaster desired. Plasters and their harder brethren, gypsum cements, are manufactured from naturally occurring, high-purity gypsum deposits. ![]()
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