What Is Polyurethane-13?
Polyurethane-13 is a man-made polymer created by reacting small building blocks called polyols and diisocyanates. In this case the polyols include trimethylolpropane, dimethylol propionic acid, hexanediol and a polyester diol derived from adipic acid while the diisocyanate component is isocyanato methylethylbenzene. When these ingredients link together they form flexible chains that dry into a thin invisible film on the skin or hair.
The earliest polyurethanes were invented in the 1930s for industrial coatings. As cosmetic chemists searched for lightweight ingredients that could give products longer wear they turned to these same film-forming polymers. Over time the recipe was tweaked to meet safety standards for personal care and Polyurethane-13 became a popular choice because it provides durable hold without feeling stiff or sticky.
Manufacturing starts with carefully measured amounts of the polyols dissolved in a solvent. The diisocyanate is added under controlled temperature and moisture-free conditions so the reactive groups can join together. After reaching the desired molecular weight the mixture is neutralized filtered and blended into a liquid dispersion that can be mixed into finished cosmetics.
You will most often see Polyurethane-13 in products that need staying power such as long-wear foundations, eyeliners, mascaras, eyebrow gels, liquid lipsticks, sunscreens, hair styling sprays and some sheet masks.
Polyurethane-13’s Cosmetic Benefits/Uses
In beauty formulas Polyurethane-13 serves one key purpose that brings several user-friendly perks.
As a film forming agent it dries into a flexible layer that locks pigments and active ingredients in place. This helps makeup resist smudging and fading through heat, sweat and natural skin oils. In sunscreens or skin treatments the film can improve water resistance so protection lasts longer between applications. On hair the same property provides light hold and frizz control while still allowing natural movement.
Who Can Use Polyurethane-13
Because it forms an airy flexible film rather than a heavy occlusive layer Polyurethane-13 is generally well tolerated by normal, dry, oily and combination skin. Sensitive or eczema-prone skin can also use it, though those groups should monitor for any redness since the polymer itself offers little soothing benefit. The ingredient is noncomedogenic so acne-prone users usually have no added risk of breakouts.
Polyurethane-13 is fully synthetic and contains no raw materials sourced from animals. That makes it suitable for vegans and vegetarians as long as the rest of the formula also meets their ethical preferences.
Current safety assessments show no reproductive toxicity, so Polyurethane-13 is not known to pose special concerns for pregnancy or breastfeeding. This is not medical advice and anyone who is pregnant or nursing should confirm product choices with a healthcare professional.
The polymer does not absorb UV light or make skin more vulnerable to the sun, so it is not considered photosensitizing. It also has no known interactions with commonly used actives such as retinoids, acids or vitamin C.
Potential Side Effects/Adverse Reactions
Responses to topical Polyurethane-13 vary from person to person. The effects listed below are only potential outcomes and most users will not experience them when the ingredient is formulated and used correctly.
- Mild skin irritation such as temporary redness or itching
- Contact allergic dermatitis in individuals sensitized to related polymers or residual monomers
- Eye irritation if the product accidentally enters the eye area before film formation is complete
- Dryness or tight feeling if the film is layered heavily or combined with high levels of alcohol
- Rare clogging of pores when used alongside very occlusive ingredients in extremely oily skin
If any of these effects occur discontinue use and seek guidance from a healthcare professional
Comedogenic Rating
Rating: 0 / 5 Polyurethane-13 is a large, inert polymer that sits on the surface and does not penetrate or mix with skin oils, so it has almost no tendency to block pores. Its lightweight flexible film allows sebum to flow out normally which keeps congestion risk very low.
Suitable for acne-prone and breakout-prone skin.
The rating can shift slightly if Polyurethane-13 is combined with heavy waxes or butters in the same formula, but on its own or in most color cosmetics it remains essentially non-comedogenic.
Summary
Polyurethane-13 is used in beauty products mainly for its film-forming ability, creating a thin flexible layer that locks pigments, actives and styling agents in place so makeup lasts longer, sunscreens stay water-resistant and hair holds style without stiffness.
While not as famous as silicones or acrylates it appears in a steady stream of long-wear foundations, eyeliners and hair sprays because chemists value its balance of durability and comfort.
Current safety data shows it is low risk with minimal irritation potential, though any cosmetic can cause a reaction for someone. When trying a new product that contains Polyurethane-13 a small patch test on clean skin for a day or two is a smart precaution.