What Is Bis-Isostearoyl Castor Oil/Dimer Dilinoleate Copolymer?
Bis-Isostearoyl Castor Oil/Dimer Dilinoleate Copolymer is a plant-derived polymer made by linking together fatty acids from castor oil with dimerized linoleic acid. Castor oil comes from the seeds of the Ricinus communis plant while linoleic acid is a fatty acid naturally present in many vegetable oils. Chemists join these building blocks through a controlled heating process that creates a larger molecule with a smooth, buttery feel.
The ingredient first appeared in cosmetics in the late 1990s when formulators looked for richer, more stable alternatives to mineral oil and animal waxes. Its plant origin, glossy texture, and strong film-forming ability quickly made it popular in lip care and skin care.
Today manufacturers blend castor oil, dimerized linoleic acid, and isostearic acid, then heat and catalyze the mixture until the fatty acids link into a uniform copolymer. The final product is purified, cooled, and delivered as a soft wax or thick liquid that melts on contact with skin.
You will find Bis-Isostearoyl Castor Oil/Dimer Dilinoleate Copolymer in lipsticks, lip balms, tinted moisturizers, hand creams, barrier creams, facial masks, and some anti-aging serums where it boosts richness and shine.
Bis-Isostearoyl Castor Oil/Dimer Dilinoleate Copolymer’s Cosmetic Benefits/Uses
This plant-based copolymer lends a mix of softness and protection to many formulas.
- Skin conditioning: It forms a lightweight film that locks in moisture, leaving skin or lips feeling smooth and supple
- Skin protecting: The film also acts as a shield against wind, cold, and everyday irritants which helps reduce dryness and chapping
Who Can Use Bis-Isostearoyl Castor Oil/Dimer Dilinoleate Copolymer
This fatty acid-based polymer works for most skin types. Its silky film is especially comforting for dry or mature skin that needs extra moisture retention. Normal and combination skin can also enjoy the soft feel without a greasy after-touch. Very oily or severely acne-prone skin may find it a little rich if applied in high amounts, though its low clogging potential makes problems unlikely for most users.
The ingredient is plant derived and contains no animal by-products so it is suitable for vegans and vegetarians.
Current safety data show no issues for people who are pregnant or breastfeeding. That said this is not medical advice and anyone expecting or nursing should run new skincare products by a healthcare professional to be on the safe side.
Bis-Isostearoyl Castor Oil/Dimer Dilinoleate Copolymer does not make skin more sensitive to the sun so no extra daytime precautions are needed beyond regular sunscreen use.
Its stable nature also means it rarely reacts with other common cosmetic ingredients which makes it easy to layer with serums or active treatments.
Potential Side Effects/Adverse Reactions
Side effects from topical Bis-Isostearoyl Castor Oil/Dimer Dilinoleate Copolymer can vary from person to person. The points below list potential reactions only and they are unlikely to occur for most users when the ingredient is correctly formulated.
- Mild redness or itching in those with a castor oil allergy
- Temporary pore congestion or small breakouts in very oil-rich skin
- Rare cases of contact dermatitis in individuals sensitive to fatty acid polymers
- Occlusive heat rash if applied in a thick layer under heavy occlusive dressings
If any of these reactions develop stop using the product and seek advice from a healthcare professional.
Comedogenic Rating
Rating: 1/5
The fatty acids in castor oil can carry a mild clogging risk, but in this copolymer they are linked into a much larger molecule that mostly sits on top of skin instead of sliding into pores. The ingredient melts on contact yet leaves a breathable film, which keeps the rating low.
Because the score is just 1, people who are prone to acne or breakouts usually tolerate it well in normal cosmetic amounts.
Real-world performance still depends on the full formula: heavy balms rich in waxes can feel denser and may tip the balance for very oily skin, while light lotions rarely cause trouble.
Summary
Bis-Isostearoyl Castor Oil/Dimer Dilinoleate Copolymer is used mainly to condition and protect skin. It does this by melting into a thin film that traps water, softens rough spots and shields against wind and cold. The glossy finish also boosts the look and feel of lip and skin products.
Though not a headline ingredient like hyaluronic acid or retinol, it is quietly popular in lip balms, creamy cleansers and barrier creams where a smooth plant-based alternative to mineral oil is needed.
Current data show a low risk of irritation, allergy or pore blockage, making it safe for most users. As with any new cosmetic, it is smart to patch test first just to confirm personal tolerance.