Styrene Isoprene Styrene Block Copolymer

Styrene isoprene styrene block copolymer is a synthetic thermoplastic elastomer made of styrene and isoprene blocks. In cosmetics it forms flexible, durable films and improves how a product holds together, feels, and adheres to skin or hair.
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Ingredient Snapshot

Overview
A film-forming polymer that helps makeup resist smudging.
Category
Tone/Texture
Type
Film Former

Ingredient Ratings

Overall Rating

Good

Comedogenic Risk

None

Skin Benefits

It forms a flexible veil that helps makeup stay put and resist smudging or cracking, improving slip for a smoother, more even application.

Uses In Skincare & Cosmetics

It's used in mascaras, eyeliners, and liquid lipsticks to improve wear and flexibility, and also appears in hair styling products and transfer-resistant foundations for better hold.

Comedogenic Rating

This ingredient is not typically evaluated for comedogenicity, and no standardized rating is available.

Safety

It's generally regarded as low irritation when used as intended. Avoid inhaling aerosols or powders containing polymers, and remove from delicate areas like lashes gently to minimize mechanical irritation.

Is Styrene Isoprene Styrene Block Copolymer a Good Ingredient?

It rates Good as a stable film former that improves wear and cohesion with typically low irritation potential, though it offers no direct skin-care activity, which is what keeps it out of the top tier.

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