A spray that beads up and rolls off a waxy leaf, a coating that crawls away from a contaminated spot, a cleaner that will not wet a greasy surface: all three are the same problem, water cannot wet a low-energy surface because its surface tension is too high. Organosilicone super-spreaders are the surfactants that solve it most dramatically, pulling water’s surface tension lower than ordinary surfactants can reach and letting a droplet spread into a wide, thin film.
The short version: an organosilicone super-spreader is a polyether-modified trisiloxane silicone surfactant. It is non-ionic, and its compact silicone structure packs so efficiently at the water surface that it drops surface tension from water’s roughly 72 mN/m to about 20 to 22 mN/m, far below the 30 to 35 mN/m that hydrocarbon surfactants reach.
That extreme reduction is what produces “super-spreading,” where a single droplet flattens into a film many times its original area. It is used as an agricultural spray adjuvant and as a wetting agent in coatings, inks, textiles, and cleaners.
Surface tension is the number that matters
Water’s high surface tension, about 72 mN/m, is why it beads on wax, leaves, and oily metal. A surfactant lowers that tension so the water can spread and wet the surface. Conventional hydrocarbon surfactants get it down to roughly 30 to 35 mN/m. An organosilicone super-spreader goes much further, to about 20 to 22 mN/m, and at that level the contact angle between droplet and surface collapses toward zero and the droplet spreads.
Why the silicone structure spreads so well
The molecule is a polyether-modified trisiloxane (CAS 27306-78-1, PubChem CID 197160); the broader commercial class is polyalkyleneoxide-modified heptamethyltrisiloxane (CAS 67674-67-3). Its hydrophobe is a small, T-shaped trisiloxane group, and its head is a water-soluble polyether chain.
That compact, flexible silicone hydrophobe packs at the air-water interface more efficiently than a long hydrocarbon tail can, which is what drives the surface tension so low. The result is described as super-spreading: a droplet does not just wet the surface, it actively spreads outward into a thin film, covering far more area than the same droplet of a conventional surfactant solution.
Where organosilicone super-spreaders are used
| Sector | Role |
|---|---|
| Agriculture | Spray adjuvant (super-spreader / super-wetter) for foliar coverage and wetting |
| Coatings and inks | Substrate wetting, flow and leveling, anti-cratering |
| Textiles | Rapid, even wetting and penetration |
| HI&I cleaning | Wetting of greasy and low-energy surfaces |
The largest market is agriculture, where the surfactant is added to a spray to improve how the spray wets and covers foliage. The selection logic against other adjuvant types is in organosilicone super-spreader vs NIS, COC, and MSO.
The catch: hydrolytic stability
Organosilicone super-spreaders have one important handling limit. The silicon-oxygen (siloxane) bonds that make the molecule so effective also hydrolyze under acidic or alkaline conditions, which breaks the surfactant down and destroys the super-spreading. In practice the products work best in a roughly neutral window, about pH 6 to 8, and a prepared spray mix should be used quickly rather than held for days.
This is the single most important fact a buyer needs after performance, and it is covered in the 24-hour rule: trisiloxane adjuvant stability and pH.
Buying organosilicone super-spreaders in bulk
RawSource supplies polyether-modified trisiloxane silicone surfactant (CAS 27306-78-1) and related trisiloxane wetting agents in drums, IBC totes, and pallets for agriculture, coatings, textiles, and cleaning, with CoA and SDS documentation. Tell us your application, target use rate, and the surface or formulation you need to wet, and request a sample to validate spreading and compatibility on your own system.
Frequently asked questions
What is an organosilicone super-spreader?
A polyether-modified trisiloxane silicone surfactant. It is non-ionic and lowers water’s surface tension to about 20 to 22 mN/m, far below hydrocarbon surfactants, which lets a droplet spread into a wide thin film. It is used as a spray adjuvant and as a wetting agent in coatings, textiles, and cleaners.
How low does a silicone surfactant lower surface tension?
A trisiloxane super-spreader lowers aqueous surface tension to roughly 20 to 22 mN/m, compared with about 72 mN/m for water alone and 30 to 35 mN/m for typical hydrocarbon surfactants. That difference is what enables super-spreading.
What does “super-spreading” mean?
It means a droplet of the surfactant solution spreads spontaneously into a thin film many times its original wetted area, because the surface tension and contact angle are driven so low. Ordinary surfactants wet a surface; super-spreaders actively spread across it.
What is the CAS number of a trisiloxane silicone surfactant?
Polyether-modified trisiloxane is CAS 27306-78-1; the broader polyalkyleneoxide-modified heptamethyltrisiloxane class is CAS 67674-67-3. Confirm the exact identity and specification on the Certificate of Analysis.
What limits the use of organosilicone super-spreaders?
Their siloxane backbone hydrolyzes outside a roughly neutral pH range, so they perform best around pH 6 to 8, and a prepared mix should be used promptly rather than stored. They are also classified as toxic to aquatic life and must be handled accordingly.
Editorial note. This article is general technical guidance for industrial, agricultural, and formulation professionals and is not application, agronomic, or regulatory advice. Organosilicone surfactants here are described by their physical surfactant function (surface tension, wetting, spreading); nothing here is a claim about pesticide performance, crop yield, or efficacy, and adjuvant use must follow the relevant product label and local regulations. The material is classified as harmful and as toxic to aquatic life (GHS Warning), so it is not an environmental-benefit product and must be handled and disposed of accordingly. Surface-tension, use-rate, and property figures are typical values to validate for your system; the Certificate of Analysis governs the material you buy. Always consult the current Safety Data Sheet (SDS) before handling. RawSource makes no warranty, express or implied, and assumes no liability for use of this information.
