TETRAETHYL ORTHOSILICATE (tetraethyl silicate)
See the summary at the top of this page. CosIng, Annex II of Regulation (EC) No 1223/2009 (prohibited substances), Consulted on 23 October 2026.
Official label name (INCIInternational name of cosmetic ingredients: the one printed on the pack. name, EU glossary of cosmetic ingredient names), No 28551
Who it concerns
What official classifications and rules say for each group. A classification describes the hazard of the pure substance, not the risk of a product that contains it, which depends on the dose and the exposure.
Prohibition or serious classificationThe text prohibits the substance for this use, or ranks it among the most serious hazards (known or presumed carcinogenic, mutagenic or reprotoxic, identified endocrine disruptor).Worth watchingThe text sets a condition or flags a hazard worth knowing: allergen, suspected effect, condition for children, hazard to the aquatic environment.For informationOfficial information with no condition on a finished product: warning to read, irritation of the pure substance.
Pregnancy and breastfeeding
No classification harmonised by the European Union covers reproduction, the unborn child or breastfeeding for this substance. This does not mean it has been judged to have no effect during pregnancy.
Babies and children
The Cosmetics Regulation sets no age-related condition for this ingredient.
Skin, eyes and allergies
For informationOfficial information with no condition on a finished product: warning to read, irritation of the pure substance.
For information Classified under the CLP Regulation: eye irritation, category 2 (Eye Irrit. 2). This classification describes the pure substance; in a finished product it is far more diluted.
Environment
No harmonised classification as hazardous to the aquatic environment, and no EU act identifies it as an endocrine disruptor for the environment.
Read on the label
The Cosmetics Regulation requires no warning to be printed for this ingredient.
Regulation (EC) No 1272/2008 (CLP), consolidated version, Annex VI table 3, retrieved 21 October 2026.
In plain words
What the rules say
No EU rule targets this ingredient specifically. It remains subject to the general rule: every product must undergo a safety assessment before it is sold (Article 10 of Regulation (EC) No 1223/2009), under the manufacturer's responsibility.
What we know about this ingredient
Uses
In weatherproofing and for hardening stone, arresting decay and disintegration; in mfr of weatherproof and acid-proof mortars and cements; in the "lost wax" process for casting of high-melting alloys.[The Merck Index, Fourteenth Edition (2006)
Tetraethyl silicate is used as a preservative for stone, brick, concrete, and plaster. It is used in water, weather- and acid-proofing processes, heat- and chemical-resistant paints, and protective coatings.
Used in ceramic processing
Weatherproof and acid-proof mortar and cements, refractory bricks, other molded objects, heat-resistant paints, chemical-resistant paints, protective coatings for industrial buildings and castings, lacquers, bonding agent intermediate.
PubChem : Hazardous Substances Data Bank (HSDB) · 2026-10-29 · CD-ROM]; Harris, R.L. (Ed.). Patty's Industrial Hygiene. Volumes 1-4. 5th Edition. John Wiley & Sons, New York, N.Y. (2000).; NASA; Phillip, WH; Technical Memorandum 102489. Polysiloxanes Derived From the Controlled Hydrolysis of Tetraethoxysilane as Precursors to Silica for Use in Ceramic Processing. 1990. Available from, as of Aug 11, 2009: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900012542_1990012542.pdf; Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 541.
Consumer uses
Binder
Insulators
Semiconductor and photovoltaic agent
Industry uses
Adhesion/cohesion promoter
Binder
Filler
Film former
Insulators
Intermediate
Sealant (barrier)
Semiconductor and photovoltaic agent
Solvent
No natural occurrence recorded in Wikidata (LOTUS database); this does not prove that the ingredient is synthetic.
Basis: one CosIngThe European Commission's database of cosmetic ingredients. CAS, with no natural occurrence recorded in this database.
Wikidata: names of substances in six languages and taxa in which they occur (largely from the LOTUS database), retrieved 23 October 2026.
Manufacturing
Preparation from absolute alcohol and silicon tetrachloride
Appearance
Colorless liquid
Water-white
Ethyl silicate appears as a clear colorless liquid with a faint odor. Flash point 125 °F. Less dense than water. Vapors are heavier than air.
Other Solid; CBI; Liquid; Liquid; Other Solid
Colorless liquid with a sharp, alcohol-like odor.
Colorless liquid with a sharp, alcohol-like odor.
PubChem : Hazardous Substances Data Bank (HSDB) · 2026-10-29 · O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 657; Flick, E.W. (ed.). Industrial Solvents Handbook 4 th ed. Noyes Data Corporation., Park Ridge, NJ., 1991., p. 868.
PubChem : CAMEO Chemicals · 2026-10-29 · https://cameochemicals.noaa.gov/chemical/3450.
PubChem : EPA Chemical Data Reporting (CDR) · 2026-10-29 · https://www.epa.gov/chemical-data-reporting.
PubChem : Occupational Safety and Health Administration (OSHA) · 2026-10-29 · https://www.osha.gov/chemicaldata/670.
PubChem : The National Institute for Occupational Safety and Health (NIOSH) · 2026-10-29 · https://www.cdc.gov/niosh/npg/npgd0282.html.
Odour described
Faint odor
SHARP, ESTER-LIKE ODOR
Sharp alcohol-like odor
PubChem : Hazardous Substances Data Bank (HSDB) · 2026-10-29 · Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 541; Browning, E. Toxicity and Metabolism of Industrial Solvents. New York: American Elsevier, 1965., p. 693; NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005).
Other names: TEOS (French), tetraethyl silicate (English), Tetraethylorthosilicat (German), Ortosilicato tetraetile (Italian), Ortossilicato de tetraetila (Portuguese).
Wikidata: names of substances in six languages and taxa in which they occur (largely from the LOTUS database), retrieved 23 October 2026.
Open Beauty Facts, export of cosmetic products, retrieved 23 October 2026.
Data “Open Beauty Facts and its contributors”, licensed under ODbL 1.0 (opendatacommons.org/licenses/odbl/1-0); derived table distributed under the same licence.
The text of the annexes
No specific rule of the EU Cosmetics Regulation names this ingredient: it is on none of its lists (prohibited, restricted, colorants, preservatives, UV filters). It may be used under the responsibility of the manufacturer, who must ensure the product is safe.
Search in Annexes II to VI. CosIng, Annex II of Regulation (EC) No 1223/2009 (prohibited substances), retrieved 23 October 2026, source updated 13 October 2026.
What has changed, and what will change
Dates of the texts that cover this ingredient. A text date may cover several substances: the details of each entry are below.
CLP classification “Flam. Liq. 3” applicable at the latest from this date (Regulation (EU) 2018/669)
Identity
- CosIng identifier
- 95055
- CAS (according to CosIng)
- 78-10-4
- EC (according to CosIng)
- 201-083-8
- Wikidata
- Q421458
- PubChem
- 6517
- ECHA InfoCard
- 100.000.986
- InChIKey
- BOTDANWDWHJENH-UHFFFAOYSA-N
CosIng inventory. CosIng, inventory of cosmetic ingredients (INCI names, CAS, EC, functions), retrieved 21 October 2026.
Wikidata, items with a CosIng identifier (P3073), retrieved 22 October 2026.
Wikidata, PubChem and ECHAEuropean Chemicals Agency. links are published only when verified: same CosIng identifier, a single item, matching CAS number.
Classified hazard (CLP Regulation)
The harmonised classification is the one set by the European Union for the whole Union. H codes refer to the hazard statements of Annex III of Regulation (EC) No 1272/2008.
tetraethyl silicate; ethyl silicate
Neither carcinogenic, mutagenic nor toxic for reproduction under the harmonised classification
- Hazard classes
- Flammable liquid, category 3 (Flam. Liq. 3)
Acute toxicity, category 4 (Acute Tox. 4)
Eye irritation, category 2 (Eye Irrit. 2)
Specific target organ toxicity, single exposure, category 3 (STOT SE 3) - Hazard statements
- H226 H332 H319 H335
Annex VI, entry 014-005-00-0, linked by CAS 78-10-4. Regulation (EC) No 1272/2008 (CLP), consolidated version, Annex VI table 3, retrieved 21 October 2026.
Entry introduced or replaced by Regulation (EU) 2018/669, applicable at the latest from 1 December 2019.
Elsewhere in the world
Information on other jurisdictions, with no effect on sale in France. What is covered, and what is not yet.
Comparison between countries
Most restrictive status in each country, and the maximum concentration cited. The details and the source of each rule follow.
| Country | Rule | Maximum concentration cited |
|---|---|---|
| European Union | No specific rule in the Cosmetics Regulation | not cited |
| United Kingdom | No specific rule in the Cosmetics Regulation | not cited |
| Switzerland | EU Regulation applies | not cited |
| United States (federal) | No federal rule recorded | not cited |
| Canada | No entry in the lists recorded | not cited |
| Japan | No entry in the lists recorded | not cited |
| South Korea | No entry in the lists recorded | not cited |
| China | Not on the prohibited lists recorded (lists of allowed substances are not recorded) | not cited |
| Australia | No entry in the lists recorded | not cited |
| ASEAN | No entry in the lists recorded | not cited |
| Taiwan | No entry in the lists recorded | not cited |
| Brazil | No entry in the lists recorded | not cited |
United Kingdom (Great Britain)
- No specific rule in the Cosmetics Regulation
Annexes II to VI in force. United Kingdom, Annexes II to VI of Regulation (EC) No 1223/2009 as retained and amended, retrieved 21 October 2026.
Contains public sector information licensed under the Open Government Licence v3.0.
Northern Ireland applies EU law.
Switzerland
Regulation (EC) No 1223/2009 applies in Switzerland (Article 54 of the Ordinance on Foodstuffs and Utility Articles).
Switzerland, FDHA Ordinance on Cosmetic Products (OCos, SR 817.023.31), consolidated version, retrieved 22 October 2026.
United States, federal rules
None of the integrated sections of the federal code (21 CFR 700.11 to 700.27 and 250.250) targets this name. The FDA does not publish a list of allowed ingredients.
United States, 21 CFR part 700 and section 250.250 (FDA rules on cosmetic ingredients), eCFR, retrieved 21 October 2026.
The eCFR is not an official legal edition of the Code of Federal Regulations.
Glossary: Commission Implementing Decision (EU) 2025/1175. Page updated on 23 October 2026.