Science
Mechanism of Action
This ingredient functions by significantly lowering the surface tension of liquids, which facilitates the emulsification of oil and water. This action allows for the efficient lifting and removal of dirt, excess oil, and other impurities from both skin and hair surfaces. Its unique properties also contribute to a conditioned skin feel post-rinsing.
Research
Clinical Evidence
Low confidenceN/A
Transparency
Dusting Analysis
As a primary cleansing surfactant, Sodium Stearoyl Methyl Isethionate is a functional ingredient typically used at significant concentrations to achieve its intended effect, rather than as a 'dusted' ingredient for superficial claims.
The Formula
Formulation
Stability
Demonstrates excellent pH stability across a range of 4.5 to 8.5, and maintains stability in aqueous formulations between pH 6 and 8 at ambient temperatures. It exhibits broad compatibility with other cosmetic ingredients.
Synergies
- Works well with a wide range of cosmetic ingredients, enhancing overall formulary performance.
Conflicts
- May induce cloudiness in formulations when certain chelating agents, such as sodium phytate, are incorporated.
- Prohibited under COSMOS specifications due to its production via ethoxylation, which raises environmental sustainability concerns.
Safety
Safety Profile
The Cosmetic Ingredient Review (CIR) Expert Panel concluded that isethionate salts, including Sodium Stearoyl Methyl Isethionate, are safe for cosmetic use when formulated to be non-irritating. At the time of the 2013 CIR report, this specific ingredient was noted as 'not in current use,' but its future use was anticipated to be in comparable categories and concentrations to other isethionate salts in the group. For instance, related sodium cocoyl isethionate was reported up to 53% in rinse-off products, and sodium lauroyl methyl isethionate up to 10.1% in rinse-off and 0.009% in leave-on products. No specific SCCS opinion was found directly for Sodium Stearoyl Methyl Isethionate, though it has an FDA UNII under broader classifications.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Sodium Stearoyl Methyl Isethionate is a highly effective and versatile cleansing surfactant, offering excellent foam and a soft skin feel across all skin types, though its ethoxylation-based production warrants environmental consideration.
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