Published · ANFA Chemical technical team
Both hydrofluoric acid and ammonium bifluoride are sources of reactive fluoride, and both attack glass and metal oxides. They are not interchangeable in every process, however. This guide compares them side by side using ANFA product data.
At a glance
| Property | Hydrofluoric acid | Ammonium bifluoride |
|---|---|---|
| Formula / CAS | HF / 7664-39-3 | NH₄HF₂ / 1341-49-7 |
| Physical form | Colourless, fuming liquid (aqueous solution) | White needle-like crystals (solid) |
| ANFA grades | Industrial 30–70% (GB/T 7744); electronic EL / UP / UP-S 49% | Export ≥ 98.0% (HG/T 3586) |
| UN number | UN 1790 | UN 1727 |
| Hazard class | Class 8 corrosive, highly toxic by inhalation and skin contact | Class 8 corrosive; releases HF with acids or heat |
| Packaging | PE drums 25 / 200 kg, 1000 L IBC, ISO tank | 25 kg bags with PE liner, 1000 kg jumbo bags |
When hydrofluoric acid is the better choice
- High-purity work – semiconductor wafer cleaning, PV texturing and optical fibre etching need electronic-grade HF with metal impurities controlled at ppb level.
- Fast, strong etching and mixed-acid stainless steel pickling.
- Chemical synthesis – production of fluoride salts and refrigerants, petroleum alkylation, rare earth refining.
- Large, continuous consumers with bulk storage and dosing systems designed for HF.
When ammonium bifluoride is the better choice
- Glass frosting and decorative etching – it produces the fine fluorosilicate layer responsible for the matte finish (see our glass frosting guide).
- Solid handling – easier to store, weigh and ship than a fuming acid; well suited to smaller users and to powder or paste formulations.
- Silicon steel surface treatment, Al-Mg alloy oxidation, boiler cleaning and rare element extraction.
Safety is not optional with either
A solid is not a "safe" form of fluoride: once ammonium bifluoride dissolves or meets acid, the solution behaves like dilute hydrofluoric acid. Use fluoride-appropriate PPE and keep calcium gluconate gel on site for both products.
How to decide
- Purity requirement – electronic applications point to HF.
- Process type – glass frosting usually favours ammonium bifluoride; stainless steel mixed-acid pickling uses HF.
- Site infrastructure – liquid HF needs acid-resistant storage and dosing; a solid needs dry storage.
- Logistics – compare packaging, dangerous-goods requirements and freight for your destination.
Still unsure? Tell us your substrate and process on the contact page. SDS and COA are provided upon inquiry confirmation.