What Is Polyester-11?
Polyester-11 is a man-made polymer created by linking together repeating molecules of 11-carbon hydroxy acids that come from castor oil. Because castor plants are a renewable crop, the raw material is considered a bio-based feedstock even though the finished polymer is fully synthetic. The idea of turning castor oil into long-chain polyesters dates back to the late 1980s when chemists were looking for lightweight, flexible films that could replace heavier waxes in personal care. Today the ingredient is manufactured in large reactors that heat and dehydrate the castor-derived acids until they join into smooth, high-purity pellets. The pellets are then ground or melted directly into cosmetic formulas.
You are most likely to see Polyester-11 in products that need a soft, breathable film on the skin or hair: facial primers, setting sprays, long-wear makeup, sheet masks, leave-on conditioners and anti-aging serums. It is prized for giving products a silky glide while helping the finished formula stay put.
Polyester-11’s Cosmetic Benefits/Uses
Below are the main ways Polyester-11 improves a cosmetic formula
- Film forming: Creates an invisible, flexible layer that locks in moisture, boosts wear time of makeup and protects the skin surface from environmental stress
- Skin conditioning: Leaves skin feeling soft and smooth without a greasy residue making textures feel more elegant and lightweight
Who Can Use Polyester-11
Polyester-11 is considered friendly for nearly every skin type. Its lightweight flexible film tends to sit well on dry, normal and combination skin while not adding extra oil to oily or acne-prone skin. Sensitive skin usually tolerates it because the polymer has a large molecular size that keeps it on the surface rather than penetrating.
The ingredient is sourced from castor beans so it is plant derived and free from animal by-products, making it suitable for vegans and vegetarians.
No evidence suggests the polymer poses a special risk to women who are pregnant or breastfeeding. Still, this is not medical advice and anyone who is expecting or nursing should run any new skincare product past a healthcare professional just to be safe.
Polyester-11 does not cause photosensitivity and contains no ingredients that would make skin more reactive to the sun. Standard daytime sun protection is still advised when using any leave-on cosmetic.
Potential Side Effects/Adverse Reactions
Responses to topical Polyester-11 vary from person to person. The issues listed below are possible but unlikely for most users when the ingredient is formulated and used correctly.
- Mild skin irritation such as redness or itching in very sensitive individuals
- Allergic contact dermatitis in users with a specific sensitivity to castor-derived materials
- Pore congestion or breakouts in people already prone to comedones if the product is very occlusive or layered heavily
- Eye irritation if the raw material or a finished product accidentally enters the eyes
If any of these reactions occur discontinue use and consult a healthcare professional for personalised guidance.
Comedogenic Rating
Rating: 1 out of 5
Polyester-11 sits on top of the skin as a light flexible film and does not bring extra oils or waxes that typically clog pores. Its large molecular size keeps it from sinking into follicles where blockages form, so the risk of new blemishes is low. That said, very thick or layered formulas that include Polyester-11 could still trap existing sebum if the overall product is heavy.
Suitable for acne-prone skin in most cases.
As with any film former, final comedogenicity depends on the full formula and how much is applied. Lighter textures like mists or serums are less likely to cause issues than rich creams.
Summary
Polyester-11 acts as a film former and skin conditioner. It forms a soft breathable layer that locks in moisture, boosts makeup wear time and leaves skin feeling smooth without greasiness.
While not as famous as silicones or other synthetic polymers, it is gaining steady popularity among brands focused on plant-derived raw materials because it comes from renewable castor oil yet delivers reliable performance.
Current safety data show it is low risk for irritation, allergy or pore clogging when used as intended. Still, every skin type is unique so a small patch test is a smart step before adding any new product that contains Polyester-11 to your routine.