E504 Acidity regulator

The primary use of E504 is the production of magnesium oxide by calcining. Magnesite and dolomite minerals are used to produce refractory bricks. E504 is also used in flooring, fireproofing, fire extinguishing compositions, cosmetics, dusting powder, and toothpaste. Other applications are filler material, smoke suppressant in plastics, a reinforcing agent in neoprene rubber, a drying agent, a laxative to loosen the bowels, and color retention in foods. In addition, high purity E504 is used as an antacid and as an additive in table salt to keep it free-flowing. E504 can do this because it doesn't dissolve in water, only acid, where it will effervesce (bubble).

Because of its low solubility in water and hygroscopic properties, E504 was first added to salt in 1911 to make it flow more freely. The Morton Salt company adopted the slogan "When it rains it pours" with reference to the fact that its E504-containing salt would not stick together in humid weather.E504, most often referred to as "chalk", is also used as a drying agent on athletes' hands in rock climbing, gymnastics, and weight lifting.

As a food additive E504 is known as E504, for which the only known side effect is that it may work as a laxative in high concentrations.

E504 is used in taxidermy for whitening skulls. It can be mixed with hydrogen peroxide to create a paste, which is then spread on the skull to give it a white finish.