Stearic Acid is useful as an ingredient in making candles, soaps, plastics, oil pastels and cosmetics, and for softening rubber. Stearic Acid is used to harden soaps, particularly those made with vegetable oil.
Stearic Acid is also used as a parting compound when making plaster castings from a plaster piece mold or waste mold and when making the mold from a shellacked clay original. In this use, powdered Stearic Acid is dissolved in water and the solution is brushed onto the surface to be parted after casting.
Esters of Stearic Acid with ethylene glycol, glycol stearate and glycol distearate are used to produce a pearly effect in shampoos, soaps, and other cosmetic products. They are added to the product in molten form and allowed to crystalize under controlled conditions.
In fireworks, Stearic Acid is often used to coat metal powders such as aluminium and iron. This prevents oxidation allowing compositions to be stored for longer.It is used along with simple sugar or corn syrup as a hardener in candies. Also it is where the common scent of crayons is derived.