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Polymethylsilsesquioxane
AKA “Silsesquioxane, Methyl Silsesquioxane, Resin Silicate”
Ingredient
Ingredient Facts
Polymethylsilsesquioxane
AKA: Methyl Silsesquioxane, Resin Silicate
Ingredient · Opacifying · EWG: 1
Synthetic
Silicone
Clean
Polymer formed by hydrolysis and condensation of methyltrimethoxysilane
CAS #
68554-70-1
Form
Liquid
See origin →
Functions
Opacifying
Adds Opacity
Creates creamy opacity
Traditional Use
Developed in the late 20th century as a silicone-based polymer. Used in modern cosmetics as a lightweight texture enhancer and mattifying agent, particularly in powders and liquid foundations.
Skin Types
●all-skin-types, gentle
Best For
General
Pregnancy & Breastfeeding Safe
Yes
EWG
1
CIR
Safe as used
Pregnancy
Yes
CIR Safety Findings
Not a Sensitizer
ewg-1
medical-approval
pregnancy-nursing-safe
all-shades-safe
Regulatory Status
USA✔ permitted
EU⚠ restricted
JAPAN⚠ restricted
CANADA⚠ restricted
Final Report: Safety Assessment of Polysilsesquioxanes as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
→
C26-28 Alkyldimethylsilyl Polypropylsilsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
C30-45 Alkyldimethylsilyl Polypropylsilsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Dimethicone/Bis-Vinyldimethicone/Silsesquioxane Crosspolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Dimethicone/Divinyldimethicone/Silsesquioxane Crosspolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Dimethicone/Silsesquioxane Copolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Dimethiconol/Silsesquioxane Copolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Diphenyl Dimethicone/Vinyl Diphenyl Dimethicone/Silsesquioxane Crosspolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Ethyl Polysilsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Hydrogen Dimethicone/Octyl Silsesquioxane Copolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Isobutyl Polysilsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Methacryloyloxypropyl Polysilsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Methoxy PEG-13 Ethyl Polysilsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Polycaprylylsilsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Polydimethylsiloxy PEG/PPG-24/19 Butyl Ether Silsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Polydimethylsiloxy PPG-13 Butyl Ether Silsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Polymethylsilsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Polymethylsilsesquioxane/Trimethylsiloxysilicate
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Polypropylsilsesquioxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Trifluoropropyl Dimethicone/Vinyl Trifluoropropyl Dimethicone/Silsesquioxane Crosspolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Vinyl Dimethicone/Methicone Silsesquioxane Crosspolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Dimethicone/Divinyldimethicone/Silsesquioxane Crosspolymer
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Dimethicone/Silsesquioxane Copolymer
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Dimethiconol/Silsesquioxane Copolymer
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Diphenyl Dimethicone/Vinyl Diphenyl Dimethicone/Silsesquioxane Crosspolymer
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Polymethylsilsesquioxane
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Polypropylsilsesquioxane
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Vinyl Dimethicone/Methicone Silsesquioxane Crosspolymer
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Evolution of Methylsilsesquioxane: From Hydrolytic Polycondensation Product to Xerogel.
Meshkov IB, Mazhorova NG, Bakirov AV, Vasil'ev SG, Kalinina AA et al.
Polymers, 2025
→
Verified Jun 2026
Data: CosIng · EWG · CIR