What Is Polyurethane-63?
Polyurethane-63 is a synthetic polymer created through a multi-step reaction that joins small molecules into a flexible yet durable network. The process starts by combining dimethylolpropionic acid and isophorone diisocyanate with a polyester diol made from adipic acid, isophthalic acid and hexanediol. This early-stage mixture, called a prepolymer, is then neutralized with triethylamine to balance its acidity and finally chain-extended with ethylenediamine to reach its full length and strength. The result is a water-dispersible polyurethane that dries to form a clear breathable film on the skin.
Although polyurethanes have been used in coatings and textiles since the 1940s cosmetic chemists adopted water-based versions like Polyurethane-63 more recently as stricter safety and environmental rules encouraged a shift away from solvent-heavy resins. Its ability to form thin, flexible films without heavy solvents made it attractive for beauty formulas starting in the late 1990s.
You will mainly find Polyurethane-63 in makeup primers, long-wear foundations, liquid eyeliners, peel-off masks, hair styling sprays and certain transfer-resistant lip products. In skin care it sometimes appears in anti-pollution or long-lasting moisturizers where a light protective layer is desired.
Polyurethane-63’s Cosmetic Benefits/Uses
In beauty products Polyurethane-63 serves one clear purpose that brings several practical advantages.
As a film former it spreads across skin or hair and dries into an invisible flexible layer. This film locks pigments in place for longer wear, improves water and rub resistance, reduces smudging, helps hold hair style and can create a smooth surface that makes makeup glide on evenly.
Who Can Use Polyurethane-63
Because the polymer dries to a breathable lightweight film most skin types, including oily, combination, normal and dry, tend to tolerate Polyurethane-63 well. Extremely sensitive or barrier-compromised skin could find any film former uncomfortable or mildly irritating so those users may prefer to limit exposure or choose shorter-wear formulas.
The ingredient is fully synthetic with no animal derived raw materials, making it suitable for vegans and vegetarians provided the finished product has not been tested on animals or blended with animal sourced additives.
Current safety data show no known reproductive or hormonal concerns and only minimal skin penetration, so Polyurethane-63 is generally viewed as low risk for pregnant or breastfeeding women. This is not medical advice and anyone who is expecting or nursing should clear any cosmetic product with their doctor first to be safe.
Polyurethane-63 is not known to cause photosensitivity and will not make skin more prone to sunburn. It can be used alongside daily sunscreen without special precautions.
Potential Side Effects/Adverse Reactions
Responses to topical Polyurethane-63 vary from person to person. The points below outline potential issues although most people will not experience them when products are correctly formulated.
- Mild contact dermatitis presenting as redness and itching in sensitive individuals
- Allergic reaction to residual monomers or amines in very rare cases
- Transient stinging if applied to broken or freshly exfoliated skin
- Eye irritation if the product migrates into the eye area before it fully sets
- Clogged pores or small bumps for users already prone to heavy congestion when very occlusive layers build up
- Respiratory irritation if aerosol hairspray containing the polymer is inhaled in a poorly ventilated space
If any adverse reaction occurs stop using the product immediately and seek advice from a qualified healthcare professional.
Comedogenic Rating
Polyurethane-63 scores a 1 out of 5 on the comedogenic scale. The polymer forms a light breathable film that is far less occlusive than heavy oils or waxes, so it rarely blocks pores. Still, buildup from layered long-wear makeup or hairline overspray can trap sweat and debris in some users which keeps it from earning a perfect zero. Overall it is generally suitable for people who are prone to acne or breakouts, provided the rest of the formula is also low in pore-clogging ingredients.
Because it is water-dispersible the ingredient rinses away more easily than traditional solvent-borne resins, further lowering the risk of congestion when proper cleansing is followed.
Summary
Polyurethane-63 is mainly valued for its film-forming ability, letting makeup, skin care or hair products lay down an invisible flexible layer that resists water, rub-off and smudging. By creating this thin shield it keeps pigments in place, smooths texture and helps hairstyles last longer without adding weight.
The material is moderately popular, showing up most often in long-wear foundations, liquid eyeliners and aerosol styling sprays but it is not as widespread as silicone gums or acrylate copolymers. Safety reviews indicate low toxicity, minimal skin absorption and only isolated reports of irritation, making it a low-risk choice for the average consumer. As with any new cosmetic it is wise to patch test first so you can catch any personal sensitivities before full-face use.