Glycol stearate is a combination of carbon, hydrogen and oxygen atoms. The substance is a product of stearic acid, a common fatty acid that is found in both plants and animals.
Typically, stearic acid and its derivatives, like glycol stearate, are produced by combining fats or oils that contain the acid, like cocoa butter and shea butter, with water at extremely high heat under intense pressure. Then, the resulting fatty substance is boiled in hot water to create steam. The steam travels through a distillation apparatus, where it condenses and releases stearic acid. Then, the acid is further processed into glycol stearate and other ingredients.
The primary use of glycol stearate is in skin and hair care products, and the substance may serve as an active ingredient or an additive in formulations. More than 600 products that are available on the market today contain glycol stearate, including everything from body lotions to professional hair relaxers and colorants. Sometimes the ingredient is listed on labels as ethylene glycol monostearate, octadecanoic acid or Emerest 2350.
To understand one of the primary ways that glycol stearate benefits the skin when used as an active ingredient, it's important to understand its structure. The hair is comprised of tiny, individual pieces of protein, and the outermost, visible layer of skin is dead tissue that is no longer performing cellular functions. Tiny spaces exist between the protein fibers of the tissue, and these can grow in size, giving the skin a rough, uneven texture.
Glycol stearate has the ability to smooth and soften the skin tissue when applied topically. Its fatty, thick texture allows it to fill in the tiny spaces that exist between the protein fibers. This makes glycol stearate what is known as an emollient. Especially beneficial for dry skin, glycol stearate is found in a wide variety of moisturizers, body lotions, body butters and even hair conditioners.
In addition to softening the skin and hair, glycol stearate also helps to cleanse it. When added to shampoos, body washes and facial cleansers, glycol stearate can function as a surfactant. This means that the ingredient helps to disrupt the natural shape of oil molecules, making them easy to wash away with water. Although it is sometimes found in bubble baths, glycol stearate does not create a foam or lather in products. As a result, manufacturers must add an additional ingredient to their formulas to produce the suds and bubbles that are expected from cleansers, shampoos and similar products.
When added to skin and hair care products in small amounts, glycol stearate can be used to make formulas less transparent to improve their visual appearance. The ingredient is also added to products to keep their liquid and oil ingredients well mixed, so that they remain more potent and effective.
The Cosmetic Ingredient Review Expert Panel has previously conducted reviews of the safety of glycol stearate, and with each review, has found that the ingredient is safe when used in skin and hair care products. Environment Canada, the leading Canadian cosmetics review panel, has also confirmed the overall safety of the ingredient. Glycol stearate is not known to have any toxic properties or to have a potential for mutagenic effects.
Studies from the Journal of the American College of Toxicology conducted during the 1980s did find that glycol stearate causes irritation on the skin in rabbits. Those with very sensitive skin or skin allergies may develop redness, itching or mild swelling from the use of glycol stearate; however in general, the ingredient is well tolerated in most people.
Sometimes, consumers confuse glycol stearate with glycol distearate, believing incorrectly that the names of these two ingredients can be used interchangeably. While glycol distearate is another ester of stearic acid, it has a different molecular structure and chemical composition. To further confuse the matter, glycol distearate does have some of the same benefits as glycol stearate and can be used as an opacifying agent in skin and hair care products.
Glycol distearate is also used to increase the thickness or viscosity of products. When added to moisturizers and conditioners, the ingredient functions as an occlusive rather than an emollient like glycol stearate. This means that glycol distearate prevents the evaporation of moisture from the skin and hair instead of lubricating and softening it.