active
Polymethylsilsesquioxane
A spherical silicone resin powder providing silky slip, light diffusion, and a soft-focus effect in colour cosmetics. Used in blush and highlighting formulations for its optical blurring properties.
Benefits
- Silky, velvety skin feel
- Soft-focus and light diffusion — optical blurring of pores and lines
- Improved wear and adhesion in powder formulas
- Reduces skin-on-powder friction
- Non-comedogenic at typical use levels
Example uses
- Highlighting blush formulas
- Powder foundations
- Mattifying primers
- Loose setting powders
- Silky bronzing products
Mechanism of action
Spherical morphology (0.5–10 micron range) creates a rolling ball effect between skin and cosmetic particles, reducing friction during application. Light scattering from the spherical PMSQ particles diffuses incident visible light, reducing the specular reflection that makes lines and pores visible.
Clinical evidence · High
Function definitively characterised. CIR safety confirmed.
Effective concentration range
1–5%
Formulation notes
Used in anhydrous powder formulas. Spherical morphology is critical for optical and sensory function. Incompatible with aqueous formulations without additional suspension aids.
Watchouts
Non-biodegradable silicone resin — same environmental persistence concerns as dimethicone. Excluded from environmentally strict clean-beauty standards.
Controversies & overclaims
Non-biodegradable silicone resin — the environmental concern is the same as other silicone polymers. Human safety not in question.
Market positioning
Marketed as optical blurring and skin-smoothing ingredient. Accurate. Environmental persistence is the relevant clean-beauty concern.
Comedogenicity
1 / 5
Sensitisation risk
Low
INCI & aliases
Polymethylsilsesquioxane
PMSQ · methyl silsesquioxane resin · silicone resin powder
Clean beauty perception
Contested in clean beauty for same reasons as dimethicone and other silicones — environmental persistence. Human safety profile is good.
Graph relationships
Timeline