C30-45 Alkyl Dimethylsilyl Polypropylsilsesquioxane — INCI reference

What it is

C30-45 Alkyl Dimethylsilyl Polypropylsilsesquioxane is a specialty synthetic silicone resin wax with a three-dimensional lattice structure. It exists as white to off-white flakes with a melting point of approximately 66°C, melting upon contact with skin to form a flexible, breathable protective film. In formulations it acts as a rheology and texture modifier for oil-in-water and water-in-oil emulsions and anhydrous gels, and as a structuring agent for sticks—particularly lipsticks. Key performance attributes include improved transfer resistance, extended makeup wear, soft-focus and mattifying effects, enhanced color coverage and intensity, and increased product stability. It is used at concentrations up to 20% in lipstick formulas and as low as 2% in emulsions. The ingredient is vegan, non-GMO, preservative-free, allergen-free, and REACH-compliant. Due to its durable film, oil-based cleansers are generally recommended for effective removal.

Safety & warnings

Recognized as safe by the Cosmetic Ingredient Review (CIR) Expert Panel. Has a comedogenic rating of 0, meaning it is not expected to clog pores despite its wax-like nature, as it forms a breathable film. REACH-compliant in Europe. Certified allergen-free and preservative-free. No known significant irritation concerns at cosmetic use concentrations. No GHS hazard classification has been established.

Origin & sourcing

Synthetic. Produced through the reaction of long-chain alkyl (C30–45) trichlorosilanes with propylsilane precursors under hydrolysis and condensation conditions to form the polypropylsilsesquioxane backbone, followed by grafting of C30–45 alkyl dimethylsilyl groups. The result is a high-molecular-weight organosilicone resin wax. No natural or plant-derived starting materials are reported.

History

Developed and commercialized by Dow Corning (now Dow Inc.) as DOWSIL SW-8005 C30 Resin Wax. The ingredient was introduced to address formulation challenges in long-wear color cosmetics, combining the film-forming properties of silicone resins with the texture and structuring benefits of silicone waxes. It has since been widely adopted in color cosmetics and sun care formulations globally.

Questions everyone asks

What does C30-45 Alkyl Dimethylsilyl Polypropylsilsesquioxane do in sunscreens?

In sunscreens it acts as a rheology modifier and film former, helping to improve texture, reduce greasiness, provide a matte to semi-matte finish, and enhance the stability and wear of the formulation without contributing to UV filtration.

Is this ingredient safe for acne-prone skin?

It has a comedogenic rating of 0, meaning it is non-comedogenic and should not clog pores. Its breathable film structure allows gas and water vapor exchange, making it generally considered suitable for acne-prone skin.

What is the commercial trade name for this ingredient?

The primary commercial product is DOWSIL SW-8005 C30 Resin Wax, manufactured by Dow Inc. (formerly Dow Corning). It is supplied as white to off-white flakes.

Why might this ingredient require an oil-based cleanser to remove?

The ingredient forms a durable, substantive film on skin that is resistant to water and transfer. Water-based cleansing alone is generally insufficient to dissolve or lift this silicone resin wax film; an oil-based or micellar cleanser is recommended for thorough removal.

Sources & references

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