Ingredient review
C26-28 Alkyl Dimethylsilyl Polypropylsilsesquioxane
INCI: C26-28 ALKYLDIMETHYLSILYL POLYPROPYLSILSESQUIOXANE
A gentle silicone film-former that improves product feel and wear without clogging pores.
In plain English
This is a type of silicone that forms a thin, breathable film on your skin. It helps creams and lotions spread easily, leaves a silky finish, and can make makeup last longer. It's not absorbed into the skin and sits on the surface, so it's generally well-tolerated even by sensitive skin.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
C26-28 Alkyl Dimethylsilyl Polypropylsilsesquioxane is generally a lower-concern ingredient when the full formula suits your skin.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging C26-28 Alkyl Dimethylsilyl Polypropylsilsesquioxane.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
A synthetic silicone polymer with long alkyl chains (C26-28) attached to a silsesquioxane backbone. It is designed to create a flexible, water-resistant film on the skin.
How it works
When applied, the molecules align to form a uniform, non-occlusive film that smooths the skin's surface. This film reduces friction (making products glide on), improves water resistance, and helps other ingredients stay in place. It also imparts a soft, velvety feel without greasiness.
Pros
Silky, non-greasy feel
Leaves a velvety finish that reduces shine without making skin feel dry or tight.
Improves product performance
Helps sunscreens resist water and sweat, and helps makeup stay put longer without caking.
Cons and cautions
Silicone-based ingredient
If you avoid silicones for environmental or personal preference, this ingredient is not suitable.
Potential for buildup
In very high concentrations or with infrequent cleansing, it may leave a slight film that some find heavy.
Best for
- Anyone looking for a smooth, silky finish in moisturizers or primers
- People who want longer-lasting makeup or sunscreen
Use caution if
- Those who prefer silicone-free formulations for personal or environmental reasons
Usage tips
Safety summary
Considered safe for topical use in cosmetics. The Cosmetic Ingredient Review (CIR) panel has reviewed similar silicone polymers and found them safe at typical use levels. Irritation and allergy are rare.
Research notes
Limited direct studies on this specific ingredient, but the broader class of alkyl silsesquioxanes is well-documented for film-forming and skin-conditioning properties. Safety data from similar silicones supports its low risk profile.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics globally, including by the EU CosIng database and the US FDA as a cosmetic ingredient. No specific restrictions.
- Common uses
- Moisturizers, Sunscreens, Primers, Color Cosmetics
- Environmental note
- As a silicone, it may not be biodegradable. Some consumers choose silicone-free products for environmental reasons, though the impact of this specific polymer is not well-studied.
Good to know
- This ingredient is considered non-comedogenic and safe for most skin types.
- It is often used in 'soft focus' or blurring primers because it fills in fine lines temporarily.
Common questions
What is C26-28 Alkyl Dimethylsilyl Polypropylsilsesquioxane in beauty products?
This is a type of silicone that forms a thin, breathable film on your skin. It helps creams and lotions spread easily, leaves a silky finish, and can make makeup last longer. It's not absorbed into the skin and sits on the surface, so it's generally well-tolerated even by sensitive skin.
What does C26-28 Alkyl Dimethylsilyl Polypropylsilsesquioxane do in a beauty product?
When applied, the molecules align to form a uniform, non-occlusive film that smooths the skin's surface. This film reduces friction (making products glide on), improves water resistance, and helps other ingredients stay in place. It also imparts a soft, velvety feel without greasiness.
Is C26-28 Alkyl Dimethylsilyl Polypropylsilsesquioxane safe for most people?
Considered safe for topical use in cosmetics. The Cosmetic Ingredient Review (CIR) panel has reviewed similar silicone polymers and found them safe at typical use levels. Irritation and allergy are rare.
Who should be careful with C26-28 Alkyl Dimethylsilyl Polypropylsilsesquioxane?
Those who prefer silicone-free formulations for personal or environmental reasons
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.