Type of Ingredient: Also known as octadecanoic acid is a fragrance ingredient, surfactant, and emulsifier.
Main Benefits: It has natural cleansing properties, capable of helping remove excess sebum (oil), dirt and bacteria from skin, hair and other surfaces.
Who Should Use It: It can be found in a variety of skin products such as soap and hair care products, shampoos, and household cleaners.
Ideal For These Concerns: Cleansing away dirt, unclogging pores and deeply moisturizing the skin.
How Often Can You Use It: You can use it twice a day.
What is stearic acid?
Stearic acid (SA) is a saturated long-chain fatty acid with an 18-carbon backbone, found in the fats of animals or plants. It is a major component of cocoa butter and shea butter. Stearic acid’s structure allows it to help improve the texture and consistency of other products. Stearic acid is a common ingredient found in many natural skincare and beauty products. However, because stearic acid is sometimes sourced from animals, it’s not always suitable for vegans or found in vegan cosmetics.
The Benefits of stearic acid
Stearic acid consists of a water-loving hydrophilic head and an oil-loving hydrophobic tail allowing it to function as a surfactant, emulsifier, and thickener when added to cosmetics and personal care products.
Surfactant is the short term for the surface-active agent. Surfactants are composites that lower the surface tension between two substances, such as two liquids or a liquid and a solid. Water molecules prefer their own company so they tend to stick together in drops, so to make water wash more efficiently, surfactants were created. They reduce surface tension so that water wets things more uniformly. Another job of surfactants is to degrease and emulsify oils and fats and dissolve soil, allowing them to be washed away. This is possible because while one end of the surfactant molecule is attracted to water, the other end is attracted to oil. Therefore, surfactants attract the oil, dirt, and other impurities that have accumulated on your skin during the day and wash them away. Due to these properties, stearic acid can be found in many different cleansers and body washes.
Stearic acid also acts as an emulsifier. When water and oil are mixed and vigorously shaken, a dispersion of oil droplets in water – and vice versa – is formed. When shaking stops, however, the two phases start to separate. To address this issue, an emulsifier can be added to the formula, which helps the droplets remain dispersed and produces a stable emulsion.
As an emulsifier, the hydrophilic head is directed to the aqueous phase and the hydrophobic tail to the oil phase.
Another property of stearic acid is its ability to function as a thickener or hardener. This is why stearic acid is added to things like soaps, candles, plastics, oil pastels, etc. It helps harden the product and also helps retain its shape.
The Food and Drug Administration (FDA) includes stearic acid on its list of direct food additives considered Generally Recognized As Safe (GRAS). The Cosmetic Ingredient Review (CIR) Expert Panel evaluated the scientific data concluded that stearic acid is safe for use in cosmetic products. According to the Cosmetics Info website, studies have shown that steric acid is non-photosensitizing (doesn’t make the skin prone to sunburns), not irritating to the eyes and non-carcinogenic. Risk is skin irritation is low.