Potassium Cetyl Sulfate
Type of Ingredient: Emulsifier or surfactant for oil/water emulsions
Main Benefits: Helps to boost SPF protection and is used in sunscreens and other cosmetics formulations.
Who Should Use It: This ingredient can be used by makeup users and can be found in water-resistant SPF products
Ideal For These Concerns: Boosting SPF protection and increasing the water-resistance of the formula.
How Often Can You Use It: Can be used daily
What is potassium cetyl sulfate?
Potassium Cetyl Phosphate is a surfactant and an emulsifying agent used as a detergent and cleansing agent. It is used in a variety of beauty products and cosmetics, including shampoos, facial cleansers, exfoliants, sunscreens, moisturizers, and makeup removers. It provides a boost for UV filters and is therefore often used in sun screen products that claim water-resistance and higher SPF protection.
The Benefits of potassium cetyl sulfate
Potassium Cetyl Phosphate is the potassium salt of a complex mixture of esters of phosphoric acid and Cetyl Alcohol, multi-functioning fatty alcohol. According to the FDA’s Voluntary Cosmetic Registration Program (VCRP) data from 2014, potassium cetyl phosphate is reported to be used in 375 formulations, the majority of which are leave-on formulations.
The primary function of potassium cetyl phosphate is as a surfactant. Surfactants are valuable cosmetic ingredients because they are compatible with both water and oil. In a formula, surfactants create structures with lipophilic portions aligning with lipids and hydrophilic portions aligning with water. This property makes surfactants ideal for cleansing and foaming formulations. For example, while rinsing with water can remove some dirt, oily deposits tend to stick to the more lipophilic surfaces of the hair and skin. After the topical application of a surfactant, the lipophilic portion will emulsify these oily deposits while the hydrophilic portion allows them to be removed from the surface of skin or hair where the rinse water washes them away.
Surfactants also function as moistening agents by lowering the surface tension between two substances, such as two liquids or a liquid and a solid. This allows surfactants to spread more easily on the surface. This property makes potassium cetyl phosphate a useful ingredient in creams and lotions.
Another function of potassium cetyl phosphate is as an emulsifier. An emulsifier is needed for products that contain both water and oil elements. Mixing water and oil creates a distribution of oil droplets in water (and vice versa). However, these two can separate if the product is left to settle. To address this problem, an emulsifier like potassium cetyl phosphate can be added to the formula. Emulsifiers also improve the consistency of a product, which facilitates an even distribution of topical skincare benefits.
The Cosmetic Ingredient Review (CIR) Expert Panel reviewed the safety of 28 alkyl phosphate ingredients, including potassium cetyl phosphate, as used in cosmetic formulas. The Panel concluded that these ingredients are safe in the present practices of use and concentration in cosmetics when formulated to be non-irritating.
But despite the approval by the CIR Expert Panel, many medical experts consider cetyl alcohol (a component of potassium cetyl phosphate) to be irritating for those with sensitive skin. Synthetic fatty alcohols like cetyl alcohol are used to alter the lipid bilayer of the epidermis and cause allergic dermal reactions. With this information, those with sensitive skin or skin conditions like eczema, rosacea, or psoriasis should perform a patch test with any product containing potassium cetyl phosphate.
Cosmetic Ingredient Review, “Safety Assessment of Alkyl Phosphates as Used in Cosmetics”, 2014, Truth In Aging, “Potassium Cetyl Phosphate”
American Oil Chemists’ Society, “An introduction to cosmetic technology”, 2015.