stearic acid, also called Octadecanoic Acid, one of the most common long-chain fatty acids, found in combined form in natural animal and vegetable fats. Commercial “stearic acid” is a mixture of approximately equal amounts of stearic and palmitic acids and small amounts of oleic acid. It is employed in the manufacture of candles, cosmetics, shaving soaps, lubricants, and pharmaceuticals.

In nature stearic acid occurs primarily as a mixed triglyceride, or fat, with other long-chain acids and as an ester of a fatty alcohol. It is much more abundant in animal fat than in vegetable fat; lard and tallow often contain up to 30 percent stearic acid.

Alkaline hydrolysis, or saponification, of fats yields soaps, which are the sodium or potassium salts of fatty acids; pure stearic acid is obtained with difficulty from such a mixture by crystallization, vacuum distillation, or chromatography of the acids or suitable derivatives. The pure acid undergoes chemical reactions typical of carboxylic acids. It is a colourless, waxy solid that is almost insoluble in water.

 Stearic Acid is mainly used in the production of detergents, soaps, and cosmetics such as shampoos and shaving cream products. Stearic acid is used along with castor oil for preparing softeners in textile sizing.

Being inexpensively available and chemically benign, stearic acid finds many niche applications It is used in the manufacture of candles, and as a hardener in candies when mixed with simple sugar and corn syrup. It is also used to produce dietary supplements.

In fireworks, stearic acid is often used to coat metal powders such as aluminum and iron. This prevents oxidation, allowing compositions to be stored for a longer period of time.

Stearic acid is a common lubricant during injection molding and pressing of ceramic powders. It is also used as a mold release for foam latex that is baked in stone molds.