What Is Bis-Trimethoxysilylethyl Tetramethyldisiloxyethyl Dimethicone?
Bis-Trimethoxysilylethyl Tetramethyldisiloxyethyl Dimethicone is a specialty silicone made by linking a dimethicone backbone with small trimethoxysilane groups. This structure lets the ingredient start out as a flowing liquid then set into a flexible film once it is spread on skin or hair. It was first explored in the late 1990s when formulators were searching for silicones that could boost the staying power of makeup without leaving a heavy feel. To make it, manufacturers react siloxane chains with trimethoxysilane in a carefully controlled process that removes excess solvents and water, giving a clear odorless fluid.
Thanks to its film-forming talent, Bis-Trimethoxysilylethyl Tetramethyldisiloxyethyl Dimethicone shows up in a variety of leave-on products. You will most often see it in long-wear foundations, primers, waterproof sunscreens, tinted moisturizers, anti-aging creams, sheet masks, hair serums and styling creams where a smooth lasting finish is key.
Bis-Trimethoxysilylethyl Tetramethyldisiloxyethyl Dimethicone’s Cosmetic Benefits/Uses
This ingredient acts as a film former, meaning it creates a thin flexible layer on the surface of skin or hair. That invisible film locks in moisture, smooths texture, improves spreadability, adds a soft touch feel, helps pigments and UV filters stay in place and boosts water resistance so products last longer through heat sweat or humidity.
Who Can Use Bis-Trimethoxysilylethyl Tetramethyldisiloxyethyl DimethiconeThis film-forming silicone is generally well tolerated by all skin types including dry, normal, combination, oily and sensitive. Its breathable flexible film rarely clogs pores, making it a good option even for acne-prone users who want long-wear coverage without a greasy feel. Extremely oily skin may prefer lighter formulations to avoid an overly silky finish, while very dry skin may want to pair it with richer hydrators since the ingredient itself is not a source of moisture.
The material is produced entirely from mineral-derived silicones, with no animal ingredients or by-products, so it is suitable for both vegans and vegetarians.
Current safety data show no reproductive or developmental concerns, and because silicones remain on the surface rather than absorbing deeply they are considered low-risk for pregnant and breastfeeding women. This is not medical advice; anyone who is pregnant or nursing should check with a healthcare professional before adding new skincare products just to be safe.
Bis-Trimethoxysilylethyl Tetramethyldisiloxyethyl Dimethicone does not increase photosensitivity. In fact the thin barrier it forms can even help hold UV filters in place when used in sunscreen formulas.
Potential Side Effects/Adverse Reactions
Side effects from topical use vary from person to person. The points below list potential reactions, but they are uncommon when the ingredient is used at the concentrations typically found in cosmetics.
- Mild skin irritation such as temporary redness or stinging
- Allergic contact dermatitis in individuals sensitive to silicones
- Transient pore congestion or breakouts in users extremely prone to acne if paired with overly occlusive ingredients
- Eye irritation or watering if the product accidentally migrates into the eyes
- Reduced absorption of actives layered underneath due to the protective film, which could interfere with treatment products meant to penetrate
If any discomfort, rash or other negative reaction occurs stop using the product and seek advice from a healthcare professional.
Comedogenic Rating
Rating: 1/5 (very low)
Bis-Trimethoxysilylethyl Tetramethyldisiloxyethyl Dimethicone sits on the surface in a weightless film that allows water vapor to pass through rather than blocking pores. Its large silicone structure is not readily absorbed and does not mix with skin oils, so it is far less likely to trap debris compared with heavier waxes or plant butters. Most clinical patch tests show minimal pore clogging at typical use levels.
Because of the low rating this ingredient is generally suitable for people who are prone to acne or breakouts.
Keep in mind overall comedogenicity depends on the full formula. Pairing this silicone with very heavy emollients or mineral oils could raise the clogging potential of the finished product.
Summary
Bis-Trimethoxysilylethyl Tetramethyldisiloxyethyl Dimethicone is a film former that creates a flexible breathable layer on skin or hair. That sheer shield locks in moisture, smooths texture, holds pigments and UV filters in place and boosts water resistance so makeup and sunscreen last longer without a heavy feel.
It is a specialty silicone so it is not as common as standard dimethicone, yet it shows up in long-wear foundations, primers and waterproof SPF where staying power matters.
Current safety data classify it as low risk with little irritation potential and minimal likelihood of clogging pores. As with any new cosmetic it is wise to patch test a product containing this ingredient before full use to make sure it agrees with your individual skin.