Calcium stearate is a

carboxylate In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, (or ). It is an ion with negative charge. Carboxylate salts are salts that have the general formula , where M is a metal and ''n'' is 1, 2,...; ''carboxylat ...

salt of

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

, classified as a calcium

soap Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are use ...

. The salt is a component of some lubricants, surfactants, as well as many foodstuffs. It is a white waxy powder.

Production and occurrence

Calcium stearate is produced by heating stearic acid and

calcium oxide Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term "''lime''" connotes calcium-containing inorganic ...

: :2 C₁₇H₃₅COOH + CaO → (C₁₇H₃₅COO)₂Ca + H₂O It is also the main component of

soap scum Soap scum or lime soap is the white solid composed of calcium stearate, magnesium stearate, and similar alkaline earth metal derivatives of fatty acids. These materials result from the addition of soap and other anionic surfactants to hard water. H ...

, a white solid that forms when soap is mixed with

hard water Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone, chalk or gypsum, which are largely made up of calcium and magnesium carbonates, bicarbo ...

. Unlike soaps containing sodium and potassium, calcium stearate is insoluble in water and does not lather well. Commercially it is sold as a 50% dispersion in water or as a spray dried powder. As a food additive it is known by the generic E number E470.

Applications

Calcium stearate is a waxy material with low solubility in water, unlike traditional sodium and potassium soaps. It is also easy and cheap to produce, and exhibits low toxicity. These attributes are the basis of many of its applications. Related applications exist for the magnesium stearate. *Calcium stearate is used as a flow agent and surface conditioner in some candies such as

Smarties Smarties are colour-varied sugar-coated chocolate confectionery. They have been manufactured since 1937, originally by H.I. Rowntree & Company in the United Kingdom, and now by Nestlé. Smarties are oblate spheroids with a minor axis of about ...

, jawbreakers and

Spree Spree may refer to: Geography * Spree (river), river in Germany Film and television * ''The Spree'', a 1998 American television film directed by Tommy Lee Wallace * ''Spree'' (film), a 2020 American film starring Joe Keery * "Spree" (''Numbers' ...

s. *It is a waterproofing agent for fabrics. *A lubricant in pencils and crayons. *A lubricant in the dry drawing method of wire production *The concrete industry uses calcium stearate for

efflorescence In chemistry, efflorescence (which means "to flower out" in French) is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves the dissolving of an internally held salt in water, or ...

control of cementitious products used in the production of concrete masonry units i.e. paver and block, as well as

waterproof Waterproofing is the process of making an object or structure waterproof or water-resistant so that it remains relatively unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in wet environme ...

ing. *In paper production, calcium stearate is used as a lubricant to provide good gloss, preventing dusting and fold cracking in paper and paperboard making. *In plastics, it can act as an acid scavenger or neutralizer at concentrations up to 1000ppm, a lubricant and a release agent. It may be used in

plastic colorant Plastic colorants are chemical compounds used to color plastic. Those compounds come in a form of dyes and pigments. The type of a colorant is chosen based on the type of a polymeric resin, that needs to be colored. Dyes are usually used with polyc ...

concentrates to improve pigment wetting. In rigid PVC, it can accelerate fusion, improve flow, and reduce die swell. *Applications in the personal care and

pharmaceutical industry The pharmaceutical industry discovers, develops, produces, and markets drugs or pharmaceutical drugs for use as medications to be administered to patients (or self-administered), with the aim to cure them, vaccinate them, or alleviate symptoms. ...

include tablet mold release, anti-tack agent, and gelling agent. *Calcium stearate is a component in some types of

defoamer A defoamer or an anti-foaming agent is a chemical additive that reduces and hinders the formation of foam in industrial process liquids. The terms anti-foam agent and defoamer are often used interchangeably. Strictly speaking, defoamers eliminate ...

s. * Anticaking agent for drugs etc.

References

{{Calcium compounds Calcium compounds Food additives Stearates