Common Name(s): Beheneth-25,c18 fatty alcohol 25-mole ethoxylate,nonionic o/w emulsifier

CAS Number: N/a

DESCRIPTION

What It Does: Beheneth-25 stabilises emulsions and builds cream viscosity by forming a packed, oriented monolayer at the oil-water interface alongside creating a lamellar crystal gel network in the water phase (at moderate eo counts) — the combination provides both thermodynamic emulsion stability and the thick, elegant texture expected in premium skin creams and lotions.

Why It's Used: Formulators select beheneth-25 because the eo count (25) provides a defined hlb, and the c18 saturated chain provides a solid, waxy structure that contributes to emulsion thickening through gel network formation. at eo counts of 2–10, the stearyl chain packs into ordered crystalline bilayers at the oil-water interface — a 'liquid crystalline' interfacial film that acts as a mechanical barrier to droplet coalescence while simultaneously building viscosity from the lamellar gel structure in the continuous phase. this combination of thermodynamic and mechanical stabilisation produces the characteristic thick, stable cream texture of classic o/w cosmetic emulsions.

How It Works: Beheneth-25 functions through two simultaneous mechanisms: (1) interfacial adsorption — the c18 stearyl chain anchors into the oil droplet surface while the 25-unit peo chain extends into the water phase, sterically preventing droplet coalescence; (2) lamellar gel network formation — at moderate eo counts, the stearyl chains of adjacent surfactant molecules interdigitate into parallel bilayers in the water phase forming a crystalline gel network that provides viscosity and mechanical emulsion stability. the gel network builds as the emulsion cools from processing temperature, creating the characteristic 'cream texture set' that formulators experience when a cream thickens on cooling. the hlb of the 25-eo version (approximately 12) positions it in the o/w emulsification range.

Typically Found In: Creams,lotions,o/w emulsion bases

TECHNICAL DETAILS

Primary Category: Active ingredient – cosmetic active

Secondary Functions: Skin conditioning

Application Areas:

Typical Concentration Range: 1%–15%

SOURCING & ETHICS

Vegan Status: Conditional - feedstock declaration required

Halal Status: Unverified - feedstock declaration required (plant, animal and petrochemical routes all exist)

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier. [audit 2026-07-29 rev2: origin-dependent: the same inci exists in plant, animal and petrochemical versions and the name does not discriminate. determination requires shariah-panel sign-off.]

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile at recommended concentrations. ewg score: 1–2.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Lamellar gel thickening at moderate eo: steareth-2 and steareth-10 form ordered lamellar crystal phases in the water phase — the c18 chains pack in parallel bilayers separated by peg water layers. this three-dimensional liquid crystal network provides zero-shear viscosity and yield stress (cream texture) while remaining shear-thinnable (spreads on application). higher eo versions (steareth-20+) become too hydrophilic to form lamellar crystals, functioning purely as o/w emulsifiers without gel thickening — the eo count controls the mechanism shift between thickening and pure emulsification within one chemical series.

Last Verified: 2026-03-12

Primary Sources: Cosing database,beheneth-25 steareth nonionic emulsifier review