Sodium Silicofluoride
Sodium silicofluoride packs fluoride into a dense, free-flowing powder that dissolves and doses predictably — the property that made it the standard choice for municipal water fluoridation long before it found steady secondary markets in ceramics, wood treatment and metal finishing.
Chelora Chemicals supplies sodium silicofluoride to water utilities, ceramic and glass manufacturers, wood-treatment plants and electroplating shops worldwide, in UN-approved packing, with a batch COA and GHS safety data sheet on every consignment.
Product identity
- CAS Number
- 16893-85-9
- IUPAC name
- Sodium hexafluorosilicate
- Molecular formula
- Na₂SiF₆
- Molecular weight
- 188.06 g/mol
- EC / EINECS
- 240-934-8
- UN Number
- 2674 · Class 6.1
- Common name
- Sodium fluorosilicate
- HS Code
- 2826 90*
* Confirm the exact HS heading with your customs broker — fluorosilicate salts can sit under a different subheading from plain fluorides depending on the destination tariff schedule.
What Sodium Silicofluoride is used for
Sodium silicofluoride is a white, odorless, free-flowing crystalline powder, only moderately soluble in water but reliably and predictably so — the property municipal engineers have relied on for decades of water fluoridation dosing. It is thermally stable and does not melt cleanly, decomposing instead at high temperature.
Its best-known use is as a water fluoridation agent, metered into municipal supplies to raise fluoride concentration to the target level for dental health. A second, longstanding industrial role is as an opacifier in ceramic glazes, enamels and opal glass, where it produces the characteristic cloudy-white finish. It is also used in wood preservation, as an insecticide component, and in electroplating for aluminium frosting and surface preparation.
Related fluorosilicate and fluoride products
- Sodium silicofluoride (this product) the standard dosing-grade fluorosilicate for water treatment and ceramic opacifying.
- Fluorosilicic acid the liquid fluorosilicate used as the alternative municipal fluoridation agent in many larger treatment plants.
- Sodium fluoride a simpler, more fluoride-dense alternative, favoured for smaller systems or where solid dosing equipment differs.
- Potassium silicofluoride the potassium analogue, used in overlapping ceramic and metal-finishing applications.
State the grade — water-treatment or industrial — on your purchase order, since certification requirements differ. See the full inorganic salt range.
Appearance and handling character
The material ships as a white, free-flowing, non-hygroscopic crystalline powder, only slightly soluble in cold water and hydrolysing slowly to release hydrofluoric acid and silica under acidic or prolonged aqueous conditions. It is toxic by ingestion and inhalation, and dust control is the primary practical handling concern. The safety section below should be read before any handling is planned.
| Parameter | Typical value |
|---|---|
| Appearance | White crystalline powder |
| Assay (Na2SiF6) | 98.5% min |
| Fluoride content | Reported per batch |
| Moisture | 0.3% max |
| Particle size | Reported per batch, graded on request |
Important: the figures above are indicative of commercial-grade material and are offered for planning only. The batch certificate of analysis is the governing document. Assay and particle size are the figures that most affect dosing accuracy — tell us your target and we will quote against it.
| Property | Value |
|---|---|
| Physical state | Free-flowing crystalline powder |
| Decomposition | > 700 °C — decomposes rather than melts |
| Density | 2.68 g/cm³ |
| Water solubility | ≈ 0.65 g/100 mL @ 25 °C |
| Hygroscopicity | Low — free-flowing under normal storage |
| Acid reactivity | Releases HF and silica under acidic hydrolysis |
Physical constants compiled from public reference data for CAS 16893-85-9 and rounded for readability. Treat them as orientation, not as a specification.
Where our customers put this salt to work
This is a dosing and formulation chemical across several unrelated industries. The applications below share only the fluoride content, not a common chemistry.
Municipal water fluoridation
Metered into drinking-water supplies as a predictable, free-flowing dosing agent to raise fluoride concentration to the target level for dental health.
- Water-treatment grade documentation
- Consistent dosing particle size
- See our water-treatment range
Ceramic & glass opacifier
Added to glazes, enamels and opal glass formulations to produce the characteristic translucent-white, opacified finish on firing.
- Ceramic and glass manufacture
- Custom particle size on request
- Technical support for your formulation
Wood preservation
Used in certain wood-preservative formulations for its fungicidal and insecticidal fluoride content, protecting timber from decay and pest damage.
- Wood-treatment plant supply
- End-use declaration required
- Bulk and bagged packaging
Electroplating & metal finishing
Used in aluminium frosting and selected surface-preparation steps in electroplating, where the fluoride chemistry etches a matte finish.
- Metal-finishing grade available
- Custom synthesis quantities available
- Technical desk review of your process
Insecticide formulation component
A minor but established role as an insecticidal active or synergist in certain older formulation types.
- End-use declaration required
- Regulatory status varies by region
- Ask our technical desk
Contract & scheduled supply
Water utilities and ceramic plants consume this material on a fixed schedule. We hold inventory and release it against your calendar.
- Annual contracts with scheduled call-off
- Price held across the contract period
- Second source held in reserve
How we supply Sodium Silicofluoride
Chelora Chemicals is a supplier and sourcing partner, not a manufacturer. On a product whose largest market is drinking-water treatment, owning no plant means we can route your order to the producer whose purity, heavy-metal profile and documentation actually clears your utility's procurement standard.
We place your order with whichever qualified producer best matches your assay, your specification, your price point and your delivery window.
We keep a second qualified source on this line. When a plant goes down for maintenance, your order switches source rather than stalling.
- Assay and fluoride content confirmed before we quote. 98.5% min is the commercial standard — we state the exact figure on the COA, critical for water-treatment dosing accuracy.
- Heavy-metal and arsenic limits verified. Water-treatment grade carries tighter impurity limits than industrial grade, and we confirm which your order needs.
- Batch COA shared before dispatch. You approve assay, moisture and particle size against your own spec while the material is still in our warehouse.
- Toxicity by ingestion and inhalation stated up front. We say so at enquiry stage so your EHS and water-safety teams can plan handling and dosing controls correctly.
- Pre-shipment samples for qualification. New account or new source, your laboratory runs a trial before the full quantity ever moves.
- Export machinery handled in-house. UN 2674 classification, approved packing, labelling, freight booking and customs paperwork are ours to manage.
Packed the way your plant receives it
Pack format drives your landed cost and your handling effort. Tell us how the material will be charged at your end and we will quote the format that suits your operation.
Lined bags / fibre drums
UN-approved lined packs for Class 6.1 solids — the standard commercial format for water-treatment and ceramic use.
Bulk bag (FIBC) / container
Bulk 1-tonne FIBC bags for continuous-consumption water utilities and ceramic plants, reducing small-pack handling.
Road / rail delivery
Bulk road or rail delivery for domestic distribution where receiving infrastructure exists at destination.
Trial / sample quantities
Small, DG-compliant packs dispatched so your utility or plant can qualify dosing and dissolution behaviour first.
Incoterms to suit you
Quoted on the Incoterm your purchasing team works to, with DG documentation filed before the booking is made.
Campaign despatch
We hold contracted tonnage and release it against your water utility's or ceramic plant's consumption calendar.
Ingestion and inhalation are the controlling routes
Sodium silicofluoride is toxic if swallowed or inhaled, and causes skin and eye irritation. Dust control during bulk handling and dosing is the primary practical concern. The summary below is orientation only — the safety data sheet supplied with your consignment is the authoritative document.
Classified hazards
H301Toxic if swallowed.H315Causes skin irritation.H319Causes serious eye irritation.H332Harmful if inhaled.H400Very toxic to aquatic life.
Hazard statements reflect classifications commonly published for CAS 16893-85-9. As a fluoride-bearing salt it should never be confused with, or stored alongside, food-grade materials — historical dosing errors at water-treatment plants have generally traced back to container mislabelling rather than the chemistry itself. Always read the SDS issued with your specific batch.
Spill & emergency orientation
Plan your response before the pallet arrives. Sections 4, 5 and 6 of the SDS are the authoritative instructions and should be posted at the point of use.
- Contain, do not hose to drain. H400 applies — collect spilled solid mechanically, avoid raising dust, and dispose of it as regulated chemical waste.
- Avoid dust generation during cleanup. Use vacuum collection or damp sweeping rather than dry sweeping where practical.
- Prevent any mix-up with food-grade materials. Clear container labelling and segregated storage prevent the dosing-error risk associated with fluoride salts at water-treatment sites.
- Treat ingestion or significant exposure seriously. Seek medical attention promptly, with the SDS in hand, even if the exposed person feels well initially.
- Rinse eyes and skin on contact. Flush with water for at least 15 minutes for eye contact; wash exposed skin with soap and water.
Storage
- Cool, dry, well-ventilated store. Away from direct sunlight and moisture; the material is not strongly hygroscopic but stores best dry.
- Keep containers tightly closed and clearly labelled. Fluoride-dosing chemicals must never be stored where confusion with food-grade salts is possible.
- Segregate from strong acids. Acidic hydrolysis releases hydrofluoric acid — keep well away from acid storage.
- Restrict access at water-treatment sites. Standard good practice for any chemical dosed into drinking-water supply.
- Shelf life typically 24 months or more. In sealed original packing. Re-assay before use after extended storage.
Handling & PPE
- Dust control during transfer and dosing. Local exhaust ventilation or enclosed dosing equipment minimises inhalation exposure during bulk handling.
- Standard chemical-handling PPE. Dust mask or respirator, chemical goggles and gloves during bagging, transfer and dosing operations.
- Never charge acid into the same vessel. Acidic conditions hydrolyse the salt and release hydrofluoric acid — maintain segregation in process design as well as storage.
- Calibrate dosing equipment regularly. Especially critical at water-treatment plants, where dosing accuracy is a public-health control point.
- Never discharge to drain or watercourse. H400 applies — contain and dispose of as regulated chemical waste.
Transport
Sodium silicofluoride moves as regulated cargo under UN 2674, Class 6.1. We classify each consignment, apply UN-approved packaging and labelling, and file the dangerous-goods declaration before the booking is made — ask us for the current DG paperwork when you plan the shipment.
What travels with every consignment
A chemical shipment is only as good as the file that travels with it. Verifying what the source plant sends is precisely the work you are buying from a supplier.
Certificate of Analysis
Batch-specific assay, fluoride content, moisture and particle size — checked against your purchase specification before release.
GHS Safety Data Sheet
Full 16-section SDS in GHS format covering hazards, exposure controls, handling, storage, spill response and disposal, issued in the language your destination requires.
Dangerous Goods Declaration
UN 2674, hazard class and IMDG or RID/ADR declaration prepared and filed before the container is booked, with correctly marked and labelled packaging.
Water-treatment compliance documentation
NSF/ANSI 60 or equivalent potable-water-treatment-chemical certification for material destined for municipal fluoridation, where required.
Third-party inspection
SGS, Intertek or Bureau Veritas sampling and inspection arranged on request before loading, giving you independent verification of what actually ships.
Retained & pre-shipment samples
Pre-shipment samples carry the same COA as the commercial lot, so what your laboratory qualifies is exactly what arrives.
A fluorosilicate salt, built for controlled dosing
Sodium silicofluoride packages fluoride and silicon together in a stable salt lattice that dissolves slowly and predictably — exactly the dosing behaviour a water-treatment plant needs. The routes below are the general industrial pattern, not a process disclosure.
React hydrofluoric or fluorosilicic acid with sodium salt
Fluorosilicic acid (itself a by-product of phosphate-fertilizer manufacture) is reacted with a sodium source to precipitate the fluorosilicate salt.
Crystallise and separate
The sodium silicofluoride crystallises out of solution and is separated by filtration or centrifugation.
Dry and grade by particle size
The crystals are dried and screened to the target granulometry for dosing or formulation use.
Package to grade specification
Water-treatment grade and industrial grade are packaged separately against their respective purity and documentation requirements.
Why assay and particle size carry through to end use
On a dosing chemical, consistency matters as much as raw purity:
- Assay sets dosing accuracy directly. Under-strength material under-doses a water supply; over-strength material risks exceeding the target fluoride concentration.
- Particle size governs dissolution rate. Water-treatment dosing equipment is calibrated to a specific dissolution behaviour — a coarser or finer grade changes that behaviour.
- Heavy-metal and arsenic limits are tighter for water-treatment grade. Reflecting the public-health sensitivity of anything dosed into drinking water.
- Moisture affects free-flow and dosing-hopper performance. A caked or clumped powder jams metering equipment.
That is why we quote against your written grade and granulometry requirement rather than a generic "fluorosilicate" label, and why the batch COA is shared for approval before dispatch.
| Material | Downstream / use |
|---|---|
| Sodium silicofluoride CAS 16893-85-9 — this product | Water fluoridation, ceramic opacifier, wood preservative |
| Fluorosilicic acid CAS 16961-83-4 | Liquid alternative for municipal water fluoridation |
| Sodium fluoride CAS 7681-49-4 | Alternative fluoridation agent, smaller systems |
| Potassium silicofluoride CAS 16871-90-2 | Overlapping ceramic and metal-finishing use |
We supply across this intermediate family — see the full intermediate range. Send the CAS number and we will confirm the correct material before quoting.
What actually moves the price of this product
Knowing what drives the quote helps you time a purchase and read whether an offer is realistic.
Fluorosilicic-acid feedstock availability
Most sodium silicofluoride is made from fluorosilicic acid, itself a by-product of phosphate-fertilizer processing — fertilizer-industry cycles affect feedstock availability.
- Phosphate-fertilizer season affects feedstock supply
- We track this on your behalf
- Contracted call-off smooths exposure
Water-treatment certification premium
NSF/ANSI 60 or equivalent certified material for municipal dosing carries a real cost premium over uncertified industrial grade.
- Confirm which grade your application needs
- We will flag when industrial grade would do
- Certification adds traceability as well as cost
Freight and DG surcharges
Class 6.1 cargo carries a hazardous surcharge; bulk utility consumers should plan freight into delivered-cost comparisons.
- Compare on landed cost, not ex-works
- DG space books out ahead of peak season
- We quote FOB, CIF, CFR or DDP as you prefer
Regional fluoridation policy shifts
Municipal fluoridation policy varies by jurisdiction and occasionally changes, directly affecting demand volume in a given market.
- We monitor regional policy developments
- Flexible contract terms where policy is in flux
- Ask us about your specific market
Source availability
A phosphate-fertilizer plant turnaround or feedstock disruption can affect fluorosilicic-acid, and therefore silicofluoride, availability.
- We hold a second qualified source on this line
- Qualify the alternate before you need it
- Ask us about dual-source contracts
| If your end use is… | Specify |
|---|---|
| Municipal water fluoridation | NSF/ANSI 60 or equivalent certified grade |
| Ceramic / glass opacifier | Industrial grade, particle size matched to your formulation |
| Wood preservative formulation | Industrial grade, end-use declaration |
| Electroplating / metal finishing | Industrial grade, custom particle size |
| Laboratory / trial | Small DG-compliant pack, full COA |
Not sure which column you are in? Describe what you make from it and our technical desk will recommend the grade — including telling you when a cheaper specification would do the job just as well.
Support that goes beyond shipping the drum
What our technical desk will do
- Confirm assay and grade before anything else. Water-treatment, ceramic and industrial grades carry different purity and documentation requirements, and we settle which one you need in the first reply.
- Confirm particle size for your dosing or formulation equipment. The wrong granulometry causes real operational problems in metering hoppers and glaze formulations alike.
- Be straight about the hazard profile. Toxic by ingestion and inhalation, very toxic to aquatic life — stated at enquiry stage so your EHS team can plan.
- Flag water-treatment certification needs early. So the right compliance documentation is in place before the material ships.
Regulatory & compliance notes
- Water-treatment chemical certification is destination-specific. Many jurisdictions require certified-grade material for municipal dosing — we confirm requirements before quoting.
- Import controls vary by destination. We check destination rules before quoting, not after you have raised the PO.
- Chemical inventory listings differ between regions. We will supply the identity data you need for that filing.
- Effluent and aquatic-toxicity rules matter. H400 applies — check your discharge consent against the material before introducing it to site.
None of the above is legal advice — your own regulatory affairs team owns the final compliance position for your import and your workplace. What we commit to is accurate product identity data, an honest statement of the hazard classification and complete documentation to work from.
From enquiry to delivered pallet
Send the specification
Grade (water-treatment or industrial), assay, particle size, quantity and destination port.
Receive a firm quote
Pricing, lead time, packing and Incoterm confirmed in writing within 24 hours — our sourcing desk is staffed around the clock.
Qualify and approve
Sample dispatched if you are qualifying a new source. Batch COA shared for your approval before the material is released.
Ship and track
UN 2674 classification filed, DG freight booked, export documents issued, and the consignment tracked through transit and clearance.
What buyers ask us about Sodium Silicofluoride
What is sodium silicofluoride used for?
Is it the same as fluorosilicic acid?
Is it toxic?
What purity do you normally supply?
What is the minimum order quantity?
How should we store it?
Is this a dangerous good? What paperwork comes with it?
Do you supply certified water-treatment grade?
Do you manufacture this yourself?
Request pricing on Sodium Silicofluoride
Send your required grade, assay, particle size, quantity and destination port. Our sourcing desk is available 24 hours a day, 7 days a week, and comes back with pricing, lead time and packing options — whether that is a single trial pack or a contracted programme for the year.