What Is Polyester-29?
Polyester-29 is a synthetic polymer created when isophorone diisocyanate reacts with a pre-made polyester that comes from combining epsilon-caprolactone and hexanediol, then finishing the chain with a small amount of 2-hydroxyethyl acrylate. The result is a flexible yet durable molecule that behaves a lot like a microscopic glue. First explored by industrial chemists looking for tougher coatings in the late 1980s, it soon found its way into beauty labs because its film-forming ability helps cosmetic formulas stay put. Production starts with heating epsilon-caprolactone and hexanediol until they link into a soft polyester. This base is treated with isophorone diisocyanate to add hard points for strength, then capped with 2-hydroxyethyl acrylate to give the finished material a handy spot for blending into water-based or oil-based mixes. Today you will mainly spot Polyester-29 in peel-off masks, long-wear foundations, waterproof eye and brow products, hair styling creams and certain anti-aging primers where a smooth, even layer is key.
Polyester-29’s Cosmetic Benefits/Uses
Polyester-29 is valued for one main job in personal care formulas: binding. By forming a thin, flexible film over skin or hair, it helps pigments, powders and other actives stick together and stay where you put them. This improves wear time, resists flaking and contributes to a smoother finish without feeling heavy.
Who Can Use Polyester-29Polyester-29 is generally considered suitable for all skin types including dry, oily and combination since it sits on the surface rather than soaking deep into pores. Sensitive skin can usually tolerate it because the molecule is inert and fragrance-free, though anyone with a known sensitivity to polyurethane or acrylate materials should approach with caution.
The ingredient is made entirely from synthetic building blocks so it contains no animal-derived substances, making it acceptable for vegans and vegetarians.
Current data shows no specific risk for women who are pregnant or breastfeeding when Polyester-29 is used in rinse-off or leave-on cosmetics. Still, this is not medical advice and expecting or nursing mothers should review any skincare product with their doctor to be safe.
Polyester-29 does not cause photosensitivity, so it will not increase the likelihood of sunburn. It also has no known incompatibility with common actives such as retinol or vitamin C, though its film-forming nature can slightly slow absorption of ingredients applied underneath.
Potential Side Effects/Adverse Reactions
Responses to topical Polyester-29 can vary from person to person. The points below list potential side effects but these outcomes are uncommon. When used in well-formulated products most users experience no problems.
- Mild skin irritation – a small number of people may notice temporary redness, itching or a stinging sensation, especially on compromised skin
- Allergic contact dermatitis – rare allergy to isocyanate or acrylate residues can lead to swelling, rash or blistering
- Eye irritation – if the ingredient migrates into the eyes it can cause watering or discomfort until rinsed away
- Build-up on hair or skin – frequent use in high concentrations may lead to a filmy residue that feels heavy or dull until cleansed
If you experience any of these effects stop using the product and seek advice from a healthcare professional.
Comedogenic Rating
Rating: 1/5. Polyester-29 sits on top of the skin as a lightweight film and does not contain heavy oils or waxes that normally clog pores. Its large molecular size keeps it from slipping into follicles, so the chance of blocked pores is low. People who break out easily can usually use it without issues, though very oily skin may prefer lighter formulas if the product also contains richer ingredients.
Because it forms a film, buildup could trap sweat or sebum if you do not cleanse well at night, so thorough removal is wise for acne-prone users.
Summary
Polyester-29 is mainly a binder and film former that holds pigments and other ingredients together, giving makeup, masks and hair products longer wear and a smoother look. It does this by laying down an invisible flexible layer that sticks to skin or hair but still moves with you.
The polymer is not as well known as silicone staples like dimethicone yet formulators reach for it when they need strong hold in waterproof liners, peel-off masks and long-wear foundation so its presence is growing.
Safety data show a low risk of irritation or acne for most users, and it is vegan friendly and free of fragrances. As with any new cosmetic, try a small patch first to be sure your skin agrees.