Potassium Fluorosilicate CAS 16871-90-2

About Potassium Fluorosilicate

Potassium fluorosilicate (potassium hexafluorosilicate, K2SiF6, CAS 16871-90-2) is an inorganic salt consisting of potassium cations and hexafluorosilicate anions. It is produced by reacting fluorosilicic acid (H2SiF6) with potassium chloride or potassium carbonate, followed by crystallization and drying.

The commercial product is a white, free-flowing crystalline powder with low solubility in water (approximately 0.12 g/100 mL at 20°C). It decomposes upon heating above 300°C, releasing silicon tetrafluoride (SiF4) and leaving potassium fluoride. Potassium fluorosilicate is primarily used in glass and ceramic manufacturing, where it serves as a fluxing agent and opacifier.

Specifications

Applications

Glass Manufacturing

Fluxing and fining agent in glass production, particularly for opal glass, frosted glass, and specialty glass products. Potassium fluorosilicate lowers melting temperature and improves glass clarity by removing bubbles. Typical addition rate is 0.5-2.0% by batch weight. Used in the production of glass fibers, optical glass, and laboratory glassware.

Ceramics & Enamels

Flux and opacifier in ceramic glazes, frits, and porcelain enamels. Potassium fluorosilicate promotes vitrification, reduces firing temperature, and improves glaze hardness and chemical resistance. Used in wall tile, sanitary ware, and tableware glazes. Typical dosage is 1-5% in glaze formulations.

Electroplating & Metal Treatment

Component in electroplating baths for zinc, nickel, and chromium plating. Potassium fluorosilicate improves plating uniformity, brightness, and corrosion resistance of deposits. Also used in metal surface treatment, conversion coatings, and anodizing baths for aluminum and magnesium alloys.

Wood Preservation

Active ingredient in wood preservative formulations for protection against fungal decay and insect attack. Potassium fluorosilicate is used in pressure treatment and dip treatment processes for utility poles, railway ties, and construction timber. Often formulated with other preservatives for broad-spectrum protection.

Other Uses

Raw material for production of potassium fluoride and hydrofluoric acid, additive in welding fluxes and soldering agents, catalyst in organic synthesis, and component in abrasive products. Also used in the manufacture of fireproofing materials and specialty chemicals.

Quality Control & Documentation

Each batch is tested before release:

1. K2SiF6 content by gravimetric analysis
2. Moisture content by gravimetric method
3. Free acid titration
4. Chloride and sulfate by ion chromatography
5. Heavy metal analysis by ICP-OES
6. Particle size distribution by sieve analysis
7. Batch-specific COA accompanies every shipment

Available documentation includes COA, TDS, SDS/MSDS, and all required shipping documents. SGS or BV pre-shipment inspection is available on request.

Storage & Handling

Store in a cool, dry, ventilated area in tightly sealed containers. Keep away from moisture, acids, and food products. Potassium fluorosilicate is stable under normal storage conditions but may release toxic fumes when heated or in contact with strong acids. Use corrosion-resistant equipment (stainless steel, HDPE, or glass-lined). Shelf life is 24 months under proper storage conditions.

Wear protective gloves, safety glasses, and dust mask when handling. Avoid inhalation of dust and prolonged skin contact. Potassium fluorosilicate is toxic if ingested and may cause skin and eye irritation. In case of eye contact, flush with water for 15 minutes and seek medical attention. Do not use in food contact applications without appropriate regulatory approval.

Frequently Asked Questions

Is potassium fluorosilicate the same as sodium fluorosilicate?

No. Potassium fluorosilicate (K2SiF6) and sodium fluorosilicate (Na2SiF6) are different salts with different solubility, melting behavior, and application profiles. Potassium fluorosilicate has lower water solubility and is preferred in certain glass and ceramic applications. They are not always interchangeable.

Can potassium fluorosilicate be used in food contact materials?

Potassium fluorosilicate is not approved for direct food contact in most jurisdictions. It may be used in manufacturing processes for glass and ceramics that subsequently become food contact materials, but residual fluoride levels must meet applicable regulatory limits. Verify with your local regulatory authority.

What is the minimum order quantity?

Standard packaging is 25 kg multi-wall paper bags and 500 kg big bags. Full container loads (20-25 tons) are typical for bulk orders. Smaller quantities are available for sample and qualification testing.

Is potassium fluorosilicate a hazardous material for shipping?

Potassium fluorosilicate is classified as a hazardous material in some jurisdictions due to its toxicity and potential to release toxic fumes. SDS and all required shipping documentation are provided with each shipment. Verify transport regulations for your specific destination.