Science
Mechanism of Action
Functioning primarily as a nonionic surfactant, STEARETH-21 reduces the surface tension between oil and water phases, allowing them to uniformly combine into stable emulsions. This action is crucial for maintaining product consistency and sensorial appeal. It also acts as a rheology modifier, optimizing viscosity, and can enhance the even distribution and potential absorption of other active ingredients on the skin.
Research
Clinical Evidence
Low confidenceN/A
Transparency
Dusting Analysis
The Formula
Formulation
Stability
STEARETH-21 demonstrates robust temperature stability, although sustained exposure above 80°C is best avoided. It tolerates high ethanol concentrations and maintains emulsion integrity across a broad pH range (3.5-7.0). It can be utilized as a primary emulsifier or in conjunction with oil-soluble emulsifiers (e.g., STEARETH-2) for superior stability.
Synergies
- Enhanced emulsion stability when combined with mostly oil-soluble emulsifiers like STEARETH-2.
Conflicts
- Can increase the penetration of other ingredients through the skin, necessitating careful formulation with actives whose safety relies on limited permeation.
Safety
Safety Profile
The independent Cosmetic Ingredient Review (CIR) panel deemed STEARETH-21 safe for cosmetic use up to 7%, provided products are formulated to be non-irritating. Potential concerns regarding 1,4-dioxane, a by-product of the ethoxylation process, are mitigated as purification steps can effectively remove it. Its use is recognized as safe by both the FDA (for related compounds as indirect food additives) and European regulatory bodies.
Your Skin
Skin Compatibility
Our Assessment
Verdict
STEARETH-21 is a valuable functional ingredient, essential for creating stable, aesthetically pleasing emulsions and enhancing the delivery and feel of sophisticated skincare formulations.
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References
Sources