What Is Trimethylsiloxysilicate/Dimethiconol Crosspolymer?
Trimethylsiloxysilicate/Dimethiconol Crosspolymer is a silicone-based ingredient created by chemically linking trimethylsiloxysilicate, a rigid resin, with dimethiconol, a flexible silicone fluid. The result is a three-dimensional network that combines the long-lasting hold of a resin with the smooth glide of a silicone oil. Both parent materials originate from silica, the same mineral that makes up sand and quartz, processed through high-temperature reactions with methyl chloride to produce siloxane building blocks. These blocks are then polymerized and crosslinked in controlled reactors, usually in the presence of a volatile carrier like cyclopentasiloxane, which is later removed or left to evaporate in the finished formula.
Silicone resins were first explored for cosmetics in the 1950s to improve water resistance in hair sprays and powders. Over time formulators discovered that blending resins with more flexible silicones reduced brittleness and enhanced comfort. This led to hybrid polymers like Trimethylsiloxysilicate/Dimethiconol Crosspolymer, which gained popularity in the 2000s as long-wear makeup and transfer-resistant skincare took off.
You will typically find this crosspolymer in products that need staying power or a luxurious feel such as long-wear foundations, liquid lipsticks, eyeliners, waterproof mascaras, matte primers, sunscreens, hair serums, styling creams, anti-frizz sprays and certain sheet or peel-off masks.
Trimethylsiloxysilicate/Dimethiconol Crosspolymer’s Cosmetic Benefits/Uses
This ingredient pulls double duty in formulations, giving both performance and texture benefits
- Film forming: Creates an invisible flexible layer that locks pigments and actives onto skin or hair, boosting water resistance, transfer resistance and overall wear time. The film also helps reduce moisture loss so skin feels smoother longer
- Viscosity controlling: Thickens oil-phase systems without greasiness, helping emulsions stay stable and giving lightweight products more body. This lets formulators achieve silky gel or cream textures that spread easily yet do not drip or feel heavy
Who Can Use Trimethylsiloxysilicate/Dimethiconol Crosspolymer
This silicone hybrid is generally well tolerated by all skin types, from dry to oily, because it forms a breathable film that helps prevent moisture loss without a greasy feel. Very acne-prone or congestion-prone users may find that heavy layers of silicone films can trap sweat or debris, so lightweight formulas or less frequent application are preferable in those cases.
The polymer is fully synthetic and derived from mineral sources, not animals, so it is suitable for vegans and vegetarians.
There is no evidence that the ingredient poses specific risks during pregnancy or while breastfeeding. It is considered non-toxic and non-sensitising, but this is not medical advice; anyone who is pregnant or nursing should show the full product ingredient list to a healthcare professional for personal guidance.
Trimethylsiloxysilicate/Dimethiconol Crosspolymer does not absorb UV light and is not known to increase photosensitivity, so it will not make skin more prone to sunburn. It also does not interfere with self-tanning agents, exfoliating acids or common actives, making it versatile for most routines.
Potential Side Effects/Adverse Reactions
Responses to topical Trimethylsiloxysilicate/Dimethiconol Crosspolymer vary from person to person. The issues listed below are only potential effects; when used correctly in a well-formulated product most people will experience none of them.
- Clogged pores or breakouts in very oily or acne-prone skin if the film traps sebum and debris underneath
- Build-up or dullness if layers are not thoroughly cleansed off, especially with long-wear makeup
- Mild irritation or redness in rare cases of sensitivity to silicones or residual solvents
- Heavy or tight skin feel if applied too thickly or in multiple products that stack similar films
- Contact allergy is extremely uncommon but possible, leading to itching or small rash patches
If any irritation, breakout or discomfort develops, stop using the product and consult a dermatologist or healthcare provider for further advice.
Comedogenic Rating
Rating: 1 out of 5
Trimethylsiloxysilicate/Dimethiconol Crosspolymer earns a low score because its large, inert silicone molecules sit on the surface instead of seeping into pores. They create a breathable film that is not oil based, so the ingredient itself rarely blocks follicles. The rating is not zero since a sturdy film can trap existing sebum and debris if used in heavy, layered products or if cleansing is insufficient.
Most acne-prone users should tolerate it well, especially in lightweight formulas.
Those who use long-wear makeup daily may want a thorough double cleanse at night to remove residual film and keep pores clear.
Summary
Trimethylsiloxysilicate/Dimethiconol Crosspolymer is valued for two key jobs: it forms an invisible flexible film that locks pigments, actives and style in place, and it thickens oil phases to give products a silky, non-greasy body. The rigid resin and flexible silicone branches crosslink into a 3D network that spreads smoothly yet dries into a durable mesh, boosting water resistance and wear time while preventing formulas from feeling heavy.
The polymer shows up in long-wear foundations, liquid lipsticks, mascaras, primers, sunscreens and anti-frizz hair serums, gaining steady popularity as consumers seek transfer-proof and humidity-resistant options. It is still less common than basic dimethicone but has become a go-to for brands chasing performance claims.
Safety studies classify it as non-toxic, non-sensitising and generally non-comedogenic. Most skin types can use it without issue, though anyone starting a new product should patch test first to be extra sure.