Methyl Glucose Sesquistearate is a mild, vegetable-derived non-ionic emulsifier that creates stable, elegant oil-in-water emulsions. It is highly valued for its skin-compatibility, providing a soft, non-greasy feel while significantly reducing the irritation potential of other surfactant systems.
- INCI Name:
- Methyl Glucose Sesquistearate
- Chemical/Scientific Name:
- Methyl Glucoside Sesquistearate; Mixture of mono- and diesters of methyl glucoside and stearic acid
- Common Aliases:
- PEG-free Sugar Emulsifier, Glucate SS
| Category: | Emulsifiers |
| Source Origin: | Vegetable (typically derived from Glucose and Stearic Acid) |
| Comedogenic Rating: | 0-1 |
| Primary Industries: | Cosmetics, Dermatology, Personal Care |
| Solubility: | Oil-soluble (dispersible in water) |
At a Glance: Properties & Effects
| Formula Stability: | |
| Texture Enhancement: | |
| Soothing/Calming: | |
| Irritation Risk: |
Primary Benefits:
- Efficiently couples oil and water phases to prevent formula separation.
- Imparts a smooth, velvety skin feel without the waxiness associated with traditional stearates.
- Exhibits high safety for sensitive areas, including the eye contour.
- Enhances the spreadability of viscous creams.
Potential Risks:
- Minimal risk of irritation, though rare sensitivity to the stearic acid component may occur in predisposed individuals.
Biological Action & Cosmetic Profile
Functioning as a non-ionic surfactant, this ingredient lowers the interfacial tension between Aqua and lipid-based components. The “sesqui-” prefix denotes a specific molecular ratio where 1.5 parts of Stearic Acid are esterified with 1 part of methyl glucoside. This unique chemical structure creates a robust liquid-crystalline matrix within the emulsion, which mimics the lipid bilayers of the skin’s stratum corneum.Molecular arrangements formed by this emulsifier provide a sustained-release mechanism for active ingredients by stabilizing the oil droplets within a multi-lamellar structure. Unlike ionic emulsifiers, which can disrupt the skin barrier, the glucose-based backbone ensures the ingredient remains exceptionally mild. It is often preferred in formulations targeting “barrier repair” because it maintains the integrity of the acid mantle during application.
Broader Applications & Origins
Sourcing for this compound typically involves renewable feedstocks, most commonly corn-derived Glucose and rapeseed-derived Stearic Acid. Because of its plant-based lineage and lack of polyethylene glycol (PEG) chains, it is a staple in “clean beauty” and ECOCERT-compliant formulations. It excels in sunscreens, where it helps evenly disperse mineral filters like titanium dioxide while ensuring the product remains sweat-resistant but breathable.
Routine Integration
Synergies:
- Co-Emulsifiers: Works optimally when paired with Cetearyl Alcohol or Sorbitan Stearate to increase viscosity and thermal stability.
- Humectants: Complements Glycerin and Sorbitol by helping lock in the hydration they provide via the stabilized emulsion film.
- Lipids: Effectively stabilizes medium-chain triglycerides like Caprylic/capric Triglyceride for lightweight facial lotions.
Conflicts:
- Universally compatible; no known chemical conflicts with common cosmetic actives.
Clinical Consensus & Safety
The Cosmetic Ingredient Review (CIR) Expert Panel has evaluated Methyl Glucose Sesquistearate across multiple decades, consistently concluding that it is safe for use in cosmetics. Dermatological patch testing reveals a very low incidence of sensitization, even at concentrations up to 10%, which exceeds typical usage levels of 1–3%. Its non-ionic nature prevents it from interacting with skin proteins, making it an ideal choice for products labeled “hypoallergenic.”
Is Methyl Glucose Sesquistearate natural?
While it undergoes chemical processing (esterification), it is considered naturally derived. The starting materials are plant-based sugars and fatty acids, making it a preferred alternative to petroleum-based PEGs.
Will this ingredient cause acne?
With a comedogenic rating of 0-1, it is highly unlikely to clog pores. Its presence in a formula is generally safe for oily and acne-prone skin types, provided the accompanying oils in the formula are also non-comedogenic.
Why is it used instead of other emulsifiers?
Formulators choose it for its superior sensory profile. It lacks the “soaping effect” (white streaking during application) common with other emulsifiers and leaves a dry, silky finish rather than a sticky residue.