What Is C24-28 Alkyldimethylsiloxy Trimethylsiloxysilicate?
C24-28 Alkyldimethylsiloxy Trimethylsiloxysilicate is a specialty silicone resin created by linking silicic acid with long-chain alkyl dimethyl siloxy groups and trimethylsiloxysilicate units. The result is a large, ladder-like molecule that is clear, flexible and highly water-repellent. Unlike naturally occurring oils or waxes, this ingredient is made through controlled laboratory reactions called hydrolysis and condensation, where silanes are mixed with water and catalysts then cured into a stable network. Silicones began appearing in beauty products in the 1950s, and chemists later modified them with longer carbon chains to boost softness and staying power. This particular resin gained popularity in the past two decades as brands looked for lightweight ways to lock makeup in place and add a silky finish.
Because it forms a breathable yet durable film, C24-28 Alkyldimethylsiloxy Trimethylsiloxysilicate is common in long-wear foundations, BB creams, primers, mascaras, eyeliners, lipsticks, sunscreens, setting sprays, face masks and even some anti-ageing serums that claim all-day moisture protection.
C24-28 Alkyldimethylsiloxy Trimethylsiloxysilicate’s Cosmetic Benefits/Uses
In formulas, this silicone brings two main benefits that improve both performance and user experience
- Film forming – Creates a thin flexible layer on skin or lashes that resists water, sweat and oil so makeup lasts longer, looks smoother and feels lightweight
- Skin protecting – Acts as a shield that slows down moisture loss and helps guard against airborne pollutants or irritants supporting soft comfortable skin throughout the day
Who Can Use C24-28 Alkyldimethylsiloxy Trimethylsiloxysilicate
This silicone resin is considered friendly for most skin types. Its light breathable film suits oily and combination skin because it helps keep excess sebum from breaking through makeup, while the protective barrier can slow water loss on dry or mature skin. Sensitive skin generally tolerates it well since the molecule is large and stays on the surface, though anyone highly reactive to silicones in general may want to proceed with caution.
The ingredient is fully synthetic and made without animal by-products so it is suitable for both vegans and vegetarians. Formulators sometimes blend it with waxes, pigments or other additives that could be animal derived, so those following a strict lifestyle should still scan the finished product label.
No specific concerns have been raised for women who are pregnant or breastfeeding. It does not penetrate deeply or enter the bloodstream in meaningful amounts. This is not medical advice and anyone who is expecting or nursing should show their routine to a healthcare professional just to be safe.
C24-28 Alkyldimethylsiloxy Trimethylsiloxysilicate does not cause photosensitivity and can be worn day or night alongside sunscreen. It also plays nicely with most common actives such as vitamin C, niacinamide or retinoids, as it tends to sit on top of the skin rather than react with them.
Potential Side Effects/Adverse Reactions
Reactions to the topical use of C24-28 Alkyldimethylsiloxy Trimethylsiloxysilicate differ from person to person. The points below list potential issues, though they are uncommon when the ingredient is used at normal cosmetic levels and manufactured correctly.
- Mild skin irritation – a small number of users may notice redness or itching, usually if their skin is already compromised
- Temporary clogged pores – heavy layered use without proper cleansing can trap debris in very acne-prone skin
- Allergic contact dermatitis – rare but possible if the immune system reacts to the silicone network or other formula components
- Eye stinging – if mascaras or liners containing the resin migrate into the eye it can cause brief discomfort or tearing
- Product build-up – daily long-wear formulas may leave a residue that needs thorough removal with an oil or balm cleanser
If you experience any of these effects stop using the product and speak with a qualified health professional for guidance.
Comedogenic Rating
Rating: 1 out of 5. C24-28 Alkyldimethylsiloxy Trimethylsiloxysilicate is a large silicone resin that sits on the skin surface rather than sinking into pores which keeps the likelihood of blocked pores low. It forms a lightweight breathable film that allows sebum to flow while still giving makeup grip and water resistance. For acne-prone or breakout-prone users this ingredient is generally considered acceptable, provided products are removed thoroughly at the end of the day to avoid residue buildup. Because the resin is often paired with pigments, waxes or heavy emollients, any congestion that occurs usually comes from those companions rather than the silicone itself.
Summary
C24-28 Alkyldimethylsiloxy Trimethylsiloxysilicate is used mainly to form a flexible water-repellent film that anchors makeup, extends wear time and slows moisture loss. Its ladder-like silicone structure creates a protective shield that feels silky instead of greasy which makes it popular in long-wear foundations, mascaras, sunscreens and setting products. While not as famous as dimethicone or cyclopentasiloxane, it is steadily gaining ground with formulators who want stronger yet still lightweight hold.
The safety profile is strong: the molecule stays on the skin surface, shows very low irritation potential and has an almost negligible comedogenic rating. Still, individual skin can react unpredictably so it is smart to patch test any new product that contains this resin before using it all over the face.