stearates

Stearates are salts or esters of stearic acid (octadecanoic acid). The term covers metal stearates such as sodium stearate, potassium stearate, calcium stearate, and magnesium stearate, as well as esters of stearic acid with alcohols, including glyceryl stearate and cetyl stearate.

Chemically, stearates are formed by neutralizing stearic acid with bases or by esterifying stearic acid with alcohols. In industry, they are produced by saponifying fats or oils with alkali metals or by direct esterification of stearic acid or glycerides. They are typically waxy solids or pastes; water solubility varies, with many metal stearates being insoluble in water but dispersible as powders, while some soap forms like sodium stearate can emulsify oils in solution.

Applications are diverse. In soaps and detergents, sodium and potassium stearates act as surfactants and cleansing agents. As lubricants and processing aids, metal stearates (calcium, magnesium, zinc) are used in plastics, rubber, ceramics, and metalworking to reduce friction and prevent sticking. In pharmaceuticals and cosmetics, magnesium and zinc stearates serve as excipients and glidants, while glyceryl stearate and cetyl stearate function as emollients and thickening agents in creams and lotions. In the food industry, calcium stearate and magnesium stearate are used as anti-caking agents and flow aids in powdered products and supplements, where permitted by regulation.

Safety and regulation vary by specific compound and use, but stearates are generally regarded as low-toxicity substances when used as intended. Regulatory status should be consulted for each application, particularly in food and cosmetics.