What Is Polyurethane-79?
Polyurethane-79 is a man-made copolymer created by linking hydrogenated polybutanediol, 1,6-hexamethylene diisocyanate, hydrogenated dilinoleyl alcohol and 1,4-butanediol, then finishing the chain with stearyl alcohol to give the molecule a smooth, waxy tail. The result is a flexible yet durable polymer that forms clear films and thickens formulas. Polyurethanes have been used in industrial coatings for decades, and during the 1990s formulators discovered that the same film-forming traits could improve the staying power of color cosmetics. Since then, specialized cosmetic grades like Polyurethane-79 have been refined to be skin friendly and easy to disperse in water or oil. The material is produced through a controlled step-growth reaction where the diisocyanate reacts with the diols under heat, followed by capping with stearyl alcohol to stabilize the ends and adjust solubility. You will most often find Polyurethane-79 in long-wear mascaras, eyeliners, brow gels, transfer-resistant foundations, hair styling creams, sunscreens and certain high-performance moisturizers that need a light, breathable film.
Polyurethane-79’s Cosmetic Benefits/Uses
When added to a formula Polyurethane-79 pulls double duty, improving both texture and performance
- Film forming: It creates an invisible flexible layer that locks pigments in place, boosts water and sweat resistance, reduces smudging and helps active ingredients stay on the skin or hair surface longer
- Viscosity controlling: The polymer thickens liquids just enough to keep them from running, giving mascaras rich body, helping foundations suspend color evenly and allowing creams to feel smooth rather than watery
Who Can Use Polyurethane-79
Because Polyurethane-79 is an inert, film-forming synthetic, it suits most skin types including normal, dry, oily and combination skins. People with very sensitive or eczema-prone skin can usually tolerate it but may want to watch for any tight or occlusive feel, as the light film it creates could aggravate pre-existing irritation if skin is already compromised.
The ingredient is fully synthetic and contains no animal-derived components, so it is considered suitable for vegans and vegetarians. As always, cruelty-free status depends on the brand’s overall testing policies rather than the polymer itself.
No specific warnings exist for pregnant or breastfeeding women regarding topical use of Polyurethane-79. Current safety data indicate it is not absorbed in significant amounts, yet this is not medical advice and anyone who is pregnant or nursing should confirm product choices with a healthcare professional.
Polyurethane-79 is not known to cause photosensitivity and will not increase sunburn risk. It is also odorless, dye-free and compatible with common actives such as vitamin C, niacinamide and sunscreens.
Potential Side Effects/Adverse Reactions
Responses to topical Polyurethane-79 differ from person to person. The points below describe potential, not expected, reactions; most users experience none of them when the ingredient is correctly formulated and used as directed.
- Mild skin irritation – occasional stinging or redness, usually in very sensitive skin
- Contact dermatitis – rare allergic rash in individuals already sensitized to polyurethanes or residual monomers
- Eye irritation – watering or burning if mascara or eyeliner containing the polymer accidentally enters the eye
- Temporary pore blockage – slight increase in clogged pores if heavy layers are not fully removed at night, more likely in acne-prone skin
If any of these reactions occur, stop using the product and seek advice from a qualified healthcare professional.
Comedogenic Rating
Rating: 1/5
Polyurethane-79 is a large, inert polymer that sits on the surface rather than sinking into pores, and it contains no inherently oily or waxy components that feed acne bacteria. Because it forms a breathable film and is usually used at low percentages, the chance of it clogging pores is minimal. The small risk comes from the physical barrier it creates, which can trap natural sebum if heavy makeup is not cleansed off thoroughly.
Overall it is considered suitable for most acne-prone or breakout-prone users, provided they remove products containing the polymer at the end of the day.
As with many film formers, how comedogenic a finished product feels depends more on the full formula and cleansing habits than on Polyurethane-79 itself.
Summary
Polyurethane-79 is mainly a film former and mild thickener that helps cosmetics stay put and feel silky. Its flexible polymer chain dries to an invisible layer that anchors pigments, boosts water and sweat resistance and keeps active ingredients on the skin surface, while its viscosity control stops liquids from running and gives creams a smooth, non-greasy glide.
The ingredient is a niche but growing favorite in long-wear mascaras, eyeliners, brow gels, transfer-resistant foundations and certain sunscreens. It is valued for durability and a light feel yet is not as widely known as older film formers like acrylates.
Current data show Polyurethane-79 is safe for topical use, causing few reactions and staying on the outer skin layers. As with any new cosmetic, perform a quick patch test when trying products that list this polymer, just to be sure your skin agrees with it.