What Is Polyurethane-73?
Polyurethane-73 is a synthetic copolymer created by reacting hydrogenated polybutadiene diol with 1,6-hexamethylene diisocyanate and hydrogenated dilinoleyl alcohol, then finishing the chain with stearyl alcohol. This combination yields a flexible, lightweight polymer that forms clear, durable films on the skin. Polyurethane chemistry has been around since the 1940s for industrial coatings, but cosmetic chemists adapted specific grades like Polyurethane-73 in the late 1990s when consumers began asking for longer-lasting makeup and lightweight skin feel. Today manufacturers produce it in closed reactors where the liquid precursors are blended, heated and carefully monitored for molecular weight, followed by purification and drying into a fine powder or viscous resin that is easy to disperse in water or oils.
You will most often see Polyurethane-73 in long-wear foundations, transfer-resistant lip colors, waterproof mascaras, peel-off masks, high-shine hair gels and some anti-aging serums that aim to create a smooth surface finish.
Polyurethane-73’s Cosmetic Benefits/Uses
In formulas Polyurethane-73 serves a couple of key roles that improve product performance and user experience
- Film forming – It lays down a flexible yet strong layer on skin or hair that helps makeup resist smudging, mascara stay waterproof, lip color stay vibrant and masks peel off in one piece.
- Viscosity controlling – It thickens emulsions and gels so they spread evenly, stay put during wear and deliver a more luxurious texture without feeling heavy or greasy.
Who Can Use Polyurethane-73
Polyurethane-73 is generally well tolerated by all skin types, including oily, combination, normal and dry skin. Its lightweight film does not trap much moisture so it rarely feels occlusive on oily or acne-prone skin, yet it helps lock in hydration for drier complexions. Sensitive skin users usually handle it well because it is nonacidic and fragrance free, but anyone with a known sensitivity to synthetic polymers should proceed cautiously.
The ingredient is made entirely from laboratory-produced raw materials and contains no animal-derived substances, so it is suitable for vegans and vegetarians.
No specific safety warnings exist for the use of Polyurethane-73 during pregnancy or while breastfeeding. Because every pregnancy is unique this is not medical advice and expectant or nursing mothers should have their healthcare provider review any new cosmetic product before use.
Polyurethane-73 does not make the skin more prone to sunburn. It has no known interactions with common active ingredients such as retinol, vitamin C or chemical exfoliants, so it can fit easily into most routines.
Potential Side Effects/Adverse Reactions
Reactions to topical Polyurethane-73 vary from person to person. The points below list potential side effects that could occur, though most users will not experience them when the ingredient is used correctly in a finished product.
- Mild skin irritation such as redness or stinging, typically in those with very reactive skin
- Contact dermatitis in rare cases where an individual is allergic to polyurethane materials
- Eye irritation if a product containing the polymer gets into the eyes, relevant for mascaras or eye shadows
- Build-up on hair shafts leading to dullness if the ingredient is used frequently in styling gels and not washed out thoroughly
If you notice any discomfort or adverse change while using a product with Polyurethane-73 stop use and consult a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1 / 5
Polyurethane-73 is a large polymer that stays on the surface of skin as a light film rather than seeping into pores. It contains no heavy oils or waxes that typically trigger blockages, so the chance of it causing comedones is low. That said, its film forming nature can slightly slow down the natural flow of sebum if layered with other occlusive ingredients, which is why it earns a 1 instead of a perfect 0.
Most people who are prone to acne can use products with Polyurethane-73 without noticing extra breakouts.
If you already use several film formers or heavy emollients in your routine, keep an eye on overall build-up since multiple layers of such ingredients could raise the risk of clogged pores over time.
Summary
Polyurethane-73 works mainly as a film former and viscosity controller. It sets down an invisible, flexible layer that makes makeup longer wearing and water resistant while also thickening creams, gels and serums so they feel silky and stay where you put them.
The polymer is fairly common in long wear foundations, waterproof eye products and peel off masks but it is not as ubiquitous as silicone elastomers or acrylate copolymers, so you may only spot it in brands that focus on high-performance or sports-proof claims.
Safety profiles show it to be low risk for irritation, low comedogenic and free of major interaction issues which makes it suitable for most skin types. Still, everyone’s skin is unique so it is smart to patch test any new product that lists Polyurethane-73 just to be sure it agrees with you.