Skip to content
CarCareTruth

Isobutyltrimethoxysilane

  • Ceramic (SiO₂)
  • CAS 18395-30-7
  • IUPAC: Trimethoxy(2-methylpropyl)silane

Isobutyltrimethoxysilane (CAS 18395-30-7) appears in 1 of the 2,122 car-care products CarCareTruth tracks (as of August 2026). It is classified as a VOC.

Low acute toxicity by standard routes. No H314/H318/H319 classified at mixture level in available SDS formulations. The trimethoxysilane leaving groups release methanol during hydrolysis and condensation curing — the trace methanol release is the primary health exposure concern at low concentrations. Not an asthmagen; no H317 skin sensitization; no H334 respiratory sensitization.

Isobutyltrimethoxysilane (IBTS; CAS 18395-30-7) is an alkoxysilane monomer used as the primary film-forming active in professional-grade ceramic paint coatings. It is the compound responsible for the silica network that gives ceramic coatings their protective hardness, hydrophobicity, and durability.

How it works: On contact with atmospheric moisture, the three methoxy groups hydrolyze to silanols, which then condense with surface hydroxyl groups on the paint's clear coat and with each other to form a cross-linked polysiloxane (silica) network. This condensation releases methanol, which evaporates during the flash and cure phases. The crosslinked silica film is the actual coating — permanent until physically removed.

Health context: At the concentrations used in professional ceramic coatings (typically 10–30%), isobutyltrimethoxysilane is not classified as a skin sensitizer (H317), respiratory sensitizer (H334), or severe eye irritant (H318) at the mixture level. Standard SDS data lists no GHS skin-sensitization pictogram. The primary in-use concern is methanol release from the hydrolysis side reaction during flash — apply in ventilated conditions to avoid vapor accumulation. Flash point of isobutyltrimethoxysilane: 113°F / 45°C (Flammable Liquid Cat 3 per GHS).

Health & environment profile

VOC
yes
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
no
Biodegradable
no
Bioaccumulative
no
Persistent
no
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
5/5
Purpose: Primary alkoxysilane active in professional ceramic coatings — bonds to paint surface via silanol condensation to form a durable protective silica-based film

Common questions about Isobutyltrimethoxysilane

What is Isobutyltrimethoxysilane used for in car care?
Primary alkoxysilane active in professional ceramic coatings — bonds to paint surface via silanol condensation to form a durable protective silica-based film
Is Isobutyltrimethoxysilane a VOC?
Yes. Isobutyltrimethoxysilane is classified as a volatile organic compound (VOC).
Is Isobutyltrimethoxysilane on California's Proposition 65 list?
No. Isobutyltrimethoxysilane is not on California's Proposition 65 list.

1 product 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.