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CarCareTruth

Ethyl silicate (TEOS)

  • Ceramic (SiO₂)
  • CAS 78-10-4
  • IUPAC: Tetraethyl orthosilicate

Ethyl silicate (TEOS) (CAS 78-10-4) appears in 2 of the 2,039 car-care products CarCareTruth tracks (as of July 2026). It is classified as a VOC.

No GHS classification as a mixture component at consumer-use concentrations (<5% in water-based formulas). At higher concentrations (pure or industrial-strength), it can cause skin and eye irritation; the hydrolysis product ethanol is also released. Used as the silica crosslinker in consumer ceramic coatings.

Tetraethyl orthosilicate (TEOS) is an alkoxysilane ester used as a silica-forming crosslinker in ceramic coatings, primers, and inorganic binders. In consumer ceramic spray coatings it is present at low concentrations (<5%) and serves as the reactive silica precursor.

Chemistry: TEOS reacts with water (from atmospheric humidity or the carrier) via hydrolysis: Si(OEt)₄ + 2H₂O → SiO₂ + 4EtOH. The resulting amorphous silica deposits on the paint surface, forming a hard, hydrophobic film. The co-product ethanol evaporates. This is the core chemistry behind the "glass-like" protective layer claimed in SiO2/TEOS ceramic coating marketing.

Safety: At consumer-product concentrations, TEOS does not carry classified GHS H-codes. Industrial-grade pure TEOS can irritate skin and eyes (H315/H319) and release flammable ethanol vapor; these hazards diminish significantly at the dilute concentrations present in consumer ceramic spray formulas.

Health & environment profile

VOC
yes
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
no
Biodegradable
yes
Bioaccumulative
no
Persistent
no
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
4/5
Purpose: Alkoxysilane crosslinker — hydrolyzes in the presence of atmospheric moisture to deposit a silica (SiO2) network on the paint surface

Common questions about Ethyl silicate (TEOS)

What is Ethyl silicate (TEOS) used for in car care?
Alkoxysilane crosslinker — hydrolyzes in the presence of atmospheric moisture to deposit a silica (SiO2) network on the paint surface
Is Ethyl silicate (TEOS) a VOC?
Yes. Ethyl silicate (TEOS) is classified as a volatile organic compound (VOC).
Is Ethyl silicate (TEOS) on California's Proposition 65 list?
No. Ethyl silicate (TEOS) is not on California's Proposition 65 list.
Is Ethyl silicate (TEOS) biodegradable?
Yes. Ethyl silicate (TEOS) has a confirmed biodegradable profile.

2 products contain this

Related

Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.