Specialty Additives Available — Bulk Only

Tetraethyl Orthosilicate (TEOS, Tetraethoxysilane)

TEOS
CAS 78-10-4 · Formula C8H20O4Si · MW 208.33 g/mol

A hydrolyzable silicate ester that lays down silicon dioxide for binding, consolidation and coating. It is used to weatherproof and consolidate stone, brick, concrete and plaster, and to formulate heat- and acid-resistant coatings, mortars and cements.

Safety Data Sheet
UN Number
UN 1292
Hazard Class
Class 3
HS Code
2920.90
At a Glance
Material Family
Specialty Additives
Record Type
Pure compound
Primary Role
Coupling / Adhesion Promotion · Crosslinking / Curing
Functional Roles
TETRAETHYL ORTHOSILICATE
NOT REPORTED
Applications & Use Cases
  • Stone/masonry consolidant: Weatherproofs and hardens stone, brick, concrete and plaster.
  • Investment casting binder: Bonds shell molds for casting high-melting alloys.
  • Heat/acid-resistant coatings: Base for chemical- and heat-resistant paints, mortars and cements.
  • Silica precursor: Source of SiO2 for sol-gel, ceramic and semiconductor processing.
Physical Properties
Physical Description
Ethyl silicate appears as a clear colorless liquid with a faint odor. Flash point 52 °C. Less dense than water. Vapors are heavier than air
Appearance
Colorless liquid
Odor
Sharp alcohol-like odor
Boiling Point
169 °C at 760 mmHg
Melting Point
-86 °C
Flash Point
52 °C (52 °C) (Open cup)
Solubility
Solubility in water: slowly hydrolyzes
Density
0.933 at 20 °C
Vapor Density
Relative vapor density (air = 1): 7.22
Vapor Pressure
Vapor pressure, Pa at 20 °C: 200
Viscosity
0.6 cP at 25 °C
Surface Tension
22.8 DYNES/CM = 0.0228 N/M AT 20 °C
Ionization Potential
9.77 eV
Odor Threshold
Water: decomposes in water; air: 17 uL/L; odor safety class D; D = 10-50% of distracted persons can detect TLV concn in the air
Refractive Index
Index of refraction: 1.3818 atT 25 °C/D
Safety & Handling
Full SDS available on request

A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.

DOT / UN Transport Classification
DOT hazard class 3 placard
UN / DOT NumberUN 1292
Hazard Class / DivisionClass 3
Packing GroupIII
Proper Shipping NameTetraethyl silicate

Transport classification per the UN Model Regulations / 49 CFR 172.101 Hazardous Materials Table. Confirm against the grade-specific SDS (Section 14) before shipping.

HS / Tariff Classification
Harmonized System (HS) Code — 6-digit international heading
2920 . 90
Chapter 29
Organic chemicals
Heading 29.20
Internationally harmonized (WCO HS)
Subheading 2920.90
6-digit international code — national tariff line adds further digits
Chemical Identity
CAS Number
78-10-4
Molecular Formula
C8H20O4Si
Molecular Weight
208.33 g/mol
IUPAC Name
tetraethyl silicate
INCI Name
TETRAETHYL ORTHOSILICATE
PubChem CID
InChI Key
BOTDANWDWHJENH-UHFFFAOYSA-N
Synonyms & Trade Names
Tetraethyl orthosilicate Tetraethoxysilane Tetraethyl silicate ETHYL SILICATE Dynasil A Silicon ethoxide Silicon tetraethoxide Silikan L Ethyl orthosilicate Tetraethoxysilicon Etylu krzemian Tetraethylsilikat Silane, tetraethoxy- Tetraethylorthosilicate TEOS Silicic acid, tetraethyl ester Silicate d'ethyle Silicate tetraethylique ES 28 (ester) Ethyl silicate, ((EtO)4Si)
Full Description

Tetraethyl orthosilicate (TEOS, CAS 78-10-4) is the tetraethyl ester of silicic acid and a primary source of silicon dioxide via hydrolysis and the sol-gel process. It is used to weatherproof and consolidate stone, brick, concrete and plaster, and to formulate heat- and acid-resistant coatings, mortars and cements. It also serves as a binder in precision investment ('lost-wax') casting of high-melting alloys and in ceramic and semiconductor processing.

Frequently Asked Questions

What is tetraethyl orthosilicate used for?

TEOS (CAS 78-10-4) is used to weatherproof and consolidate stone, brick, concrete, and plaster; as a binder in precision investment (lost-wax) casting of high-melting alloys; in heat- and acid-resistant coatings, mortars, and cements; and as a silica (SiO2) precursor for sol-gel, ceramic, and semiconductor processing.

Is tetraethoxysilane the same as tetraethyl orthosilicate?

Yes. Tetraethoxysilane, tetraethyl orthosilicate, TEOS, and ethyl silicate all refer to the same compound, C8H20O4Si (CAS 78-10-4), the tetraethyl ester of silicic acid.

What is an example of an orthosilicate?

TEOS itself is an orthosilicate ester, the tetraethyl ester of orthosilicic acid. It hydrolyzes to release silicon dioxide, which makes it a primary silica source in the sol-gel process.

How does TEOS ship under DOT?

TEOS is assigned UN 1292 (ETHYL SILICATE), a flammable liquid. Confirm the packing group, packaging, and documentation against the current SDS before shipping.

What is the cost of bulk TEOS?

Bulk TEOS pricing depends on volume and packaging. Request a quote from RawSource with your target quantity; it ships in drums and totes with CoA and SDS available on request.

Disclaimer. Information on this page — including properties, identifiers, hazard, transport (DOT/UN) and tariff (HS) classifications, and applications — is provided for general reference and is compiled from authoritative public sources (e.g. PubChem/ECHA, 49 CFR 172.101, the Harmonized Tariff Schedule). Values are typical and are not a guaranteed specification; the Certificate of Analysis (CoA) for the lot purchased governs. Products are sold for industrial and professional use only. Nothing here is a medical, health, or efficacy claim or advice. Always consult the current Safety Data Sheet (SDS) before handling, storage, transport or disposal, and confirm regulatory status, classification and suitability for your application and jurisdiction. Hazard, transport and tariff classifications must be verified for your specific shipment. RawSource makes no warranty, express or implied, and assumes no liability for use of this information. Trademarks. Third-party trademarks and brand names are the property of their respective owners; any reference is nominative — used only to identify a comparable product — and does not imply affiliation with, sponsorship by, or endorsement by the trademark owner.