Clean silica source
Hydrolyzes to silica and ethanol, leaving no sodium or other metal ions in the binder or film.
Si-28
Ethyl Silicate 28 (TEOS) Supplier from China
Ethyl silicate 28 (tetraethyl orthosilicate, TEOS) is the silica source behind investment-casting binders, inorganic zinc-rich primers and sol–gel coatings, and a crosslinker for RTV silicones. SUNCHEM supplies 99% min. TEOS in 190 kg drums or IBCs, with a batch COA on every shipment.
CAS 78-10-4 · Si(OC₂H₅)₄ · Tetraethyl orthosilicate
- Lot COA with every shipment
- Samples for your trials
- Technical support for your trial
Product overview & key benefits
TEOS is a monomeric silicate ester containing about 28% SiO₂ by weight — hence the name Ethyl Silicate 28. When it hydrolyzes it releases ethanol and forms silanol groups that condense into a silica network. That reaction binds refractory shells for precision casting, cures inorganic zinc-silicate primers, deposits silica films and particles by sol–gel, and crosslinks condensation-cure silicone rubber.
For most users the key numbers are assay, water and acidity, because they control how fast the material hydrolyzes and how stable a prepared binder stays.
Controllable cure
Hydrolysis rate is set by water, catalyst and solvent, so binder pot life and cure can be tuned to your process.
Drum or IBC supply
190 kg drums for smaller sites, IBCs for continuous users, with a batch COA for every lot.
Technical specifications
| Parameter | Typical value |
|---|---|
| Product name | Ethyl Silicate 28 (TEOS) |
| Synonyms | Tetraethyl orthosilicate; tetraethoxysilane; Si-28 |
| CAS No. | 78-10-4 |
| EC No. | 201-083-8 |
| Molecular formula | C₈H₂₀O₄Si |
| Molecular weight | 208.33 |
| Appearance | Colorless clear liquid |
| Assay | ≥99% |
| SiO₂ content (theoretical) | 28.8% |
Assay is the typical value for our standard grade. Water, acidity and chloride limits depend on the producer grade and are stated on the TDS and batch COA; the limits for your order are confirmed in the quotation and contract.
Applications by Industry
Where TEOS is used, and what to confirm before you switch supply.
Investment-casting binders
Prehydrolyzed with water, alcohol and an acid catalyst to make the silica binder for ceramic shell molds in precision casting.
Check before trial
- Binder recipe and target SiO₂ content
- Prehydrolysis done in-house or by your binder supplier
- Drum or IBC and monthly use
Zinc-rich & heat-resistant coatings
The binder base for inorganic zinc-silicate primers on steel, and for high-temperature silicate coatings.
Check before trial
- Coating system and cure conditions
- Water and acidity limits
- Storage time before use
RTV silicone crosslinker
Crosslinker for condensation-cure (RTV-2) silicone rubbers, sealants and mold-making compounds.
Check before trial
- Catalyst system
- Purity you need
- Pack size
Sol–gel silica & specialty uses
Precursor for silica sols, aerogels, glass coatings and catalyst supports.
Check before trial
- Purity and metal limits for your use
- Sample size for lab work
- Documents you need
Selection & comparison
Choosing for your process
| Your requirement | What usually works |
|---|---|
| Precision-casting shells | Ethyl Silicate 28 prehydrolyzed to your binder recipe |
| Inorganic zinc-rich primer | Ethyl Silicate 28; agree water and acidity limits |
| RTV silicone crosslinking | Standard 99% min. TEOS |
| Continuous high-volume use | IBC supply |
| Replacing an existing supplier | Send your current TDS or COA; we quote against the parameters you approve |
Packaging & storage
Packaging
190 kg drums or IBCs.
Storage
Keep containers tightly closed in a cool, dry, well-ventilated area; moisture slowly hydrolyzes TEOS. Keep away from heat and ignition sources and follow the SDS.
Transport
Flammable liquid for transport (UN 1292, Class 3, PG III).
From first email to approved supply
Name the use
Casting binder, zinc primer, silicone or sol–gel: each sets different limits for water and acidity.
Compare the numbers that matter
Assay, water, acidity and chloride. Ask for the same parameters on our COA that appear on your incoming-inspection sheet.
Plan storage and transport
TEOS is a Class 3 flammable liquid and slowly reacts with moist air. Agree drum or IBC, and use opened containers promptly.
Trial, then lock the spec
Run a sample in your own process and keep the approved lot COA as the reference for contract limits.
Tell us your requirement. We match the grade.
Tell us how you use TEOS, the quantity and the destination port. Add your current specification and we will quote against it.
| Information | Example |
|---|---|
| Application | Casting binder, zinc primer, RTV silicone, sol–gel |
| Required specification | Assay, water, acidity |
| Packaging | 190 kg drum or IBC |
| Quantity | Trial order / monthly / annual volume |
| Destination | Country and port |
| Documents needed | COA, SDS, TDS, REACH statement |
Related products
Ethyl Silicate 28 (TEOS) FAQ
What does the "28" in Ethyl Silicate 28 mean?
It refers to the silica content: monomeric tetraethyl orthosilicate contains about 28% SiO₂ by weight.
What is ethyl silicate 28 used for?
Mainly as the silica binder for investment-casting shells and inorganic zinc-rich primers. It is also a crosslinker for RTV silicone rubber and a precursor for sol–gel silica.
How is TEOS packed?
In 190 kg drums or IBCs. It is a flammable liquid for transport (UN 1292, Class 3, PG III).
How should TEOS be stored?
Tightly closed, in a cool, dry and ventilated area away from ignition sources. Moist air slowly hydrolyzes it, so use opened containers promptly.
