Carbomer is one of the most common thickeners in skincare. It has been used in cosmetics for decades, and you will find it in gels, lotions, creams and shampoos. Here is what it is, what it does in a formula, and what to know about its safety.
The scientific background of Carbomer
Carbomers are high molecular weight polymers of acrylic acid, cross linked into a network that swells in water. On an ingredient list they appear as “Carbomer”. Although they start from acrylic acid, the finished polymer is a different material from raw acrylic acid.
Aspect and consistency
Carbomer is supplied as a fluffy white powder. In a finished product it forms a clear to slightly hazy gel once it is dispersed in water and neutralized.
What does carbomer do in a formula?
Carbomer is a rheology modifier: it controls how thick a product is and how it flows. The powder is dispersed in water, where it swells. When a neutralizing agent raises the pH (typically to around 6-7), the polymer chains uncoil and the mixture thickens into a gel. This gives the product its texture and helps keep particles and oil droplets from separating.
Carbomer is not a true emulsifier. It supports the stability of an emulsion by increasing viscosity, but emulsions still need a separate emulsifier system.
Benefits of adding Carbomer
- Thickens water-based formulas: it can create clear gels at low concentrations, typically below 1%.
- Suspends particles and oil droplets: it keeps ingredients from settling or separating.
- Supports emulsion stability: by raising viscosity, alongside the emulsifier.
- Smooth texture: carbomer gels thin out when rubbed and thicken at rest, which gives an easy to spread feel.
How safe is Carbomer?
Expert safety reviews, such as the Cosmetic Ingredient Review (CIR) panel’s, have found carbomers safe as used in cosmetic products at typical concentrations. They are large polymers that are not readily absorbed through the skin, and irritation or sensitization is uncommon. Still, no ingredient is risk free, and anyone with very sensitive skin or a known allergy should patch test a new product.
Should you use Carbomer?
Chances are you already use it: carbomer appears in many gels, creams, lotions and shampoos, so it is hard to avoid. For most people it is a well tolerated, low irritation ingredient.
It does have limits. Carbomer gels are sensitive to salts and to low pH, so formulas with a high mineral content, such as products containing Dead Sea salt, need special handling.
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