Published · ANFA Chemical technical team
Hydrofluoric acid (HF, CAS 7664-39-3) is rarely the main acid in a cleaning product, but small additions can do things no other common acid can: dissolve silica and silicate deposits, remove tenacious oxide films from aluminium and stainless steel, and speed up the attack of other acids on mixed scale. That is why formulators of industrial cleaning agents use HF — or fluoride sources such as ammonium bifluoride — in a number of specialised products.
HF is also one of the most dangerous chemicals in routine industrial use. This guide explains where it is used in cleaning formulations and the safety rules that must accompany every application. It is intended for professional formulators and plant engineers, not for consumer products.
Why add HF to a cleaning formulation?
- Silica and silicate dissolution. HF is the only common mineral acid that readily dissolves SiO2. Scale containing silica or silicates is often resistant to hydrochloric, sulfuric or citric acid alone.
- Oxide-film removal. Fluoride attacks the passive oxide layers on aluminium, stainless steel and titanium, producing a clean, active or bright surface.
- Synergy with other acids. In blends with phosphoric, sulfuric, nitric or hydrochloric acid, a small fluoride addition can accelerate cleaning and improve uniformity.
- Metal complexing. Fluoride complexes iron, aluminium and other metals, helping to keep them in solution.
Main application areas
Aluminium cleaners and brighteners
Acid aluminium cleaners — for vehicle bodies, truck trailers, tanks and architectural aluminium — often combine phosphoric and/or sulfuric acid with a small fluoride component. The fluoride removes the oxide film and road film to restore a bright appearance. Over-concentration or long contact quickly causes etching, staining and dulling, so formulation and dilution instructions are critical.
Stainless steel pickling and brightening
Pickling pastes, gels and spray solutions used to remove weld heat tint and scale from stainless steel are typically based on nitric acid with HF or a fluoride salt. They restore the chromium-rich passive layer after rinsing. For the full process view see our guide to stainless steel pickling with HF and our metal surface treatment blends.
Industrial descaling
Cooling systems, evaporators, process vessels and pipework can build up mixed scale of carbonates, iron oxides and silicates. Descaling formulations based on hydrochloric or other acids sometimes include HF or ammonium bifluoride specifically to tackle the silicate fraction, together with corrosion inhibitors that protect the base metal.
Boiler and heat-exchanger cleaning
Chemical cleaning of boilers and heat exchangers removes iron oxide and mineral deposits that reduce heat transfer. Where deposits contain silica, fluoride (as HF or ammonium bifluoride) is commonly added to the hydrochloric acid cleaning solution. Dilute HF solutions have also been used for cleaning certain boiler systems. These jobs are normally carried out by specialist contractors following a written cleaning procedure, with inhibitor selection, temperature limits, corrosion coupons and neutralisation steps defined in advance.
Other uses
Fluoride-containing cleaners are also used for masonry and brick cleaning and in some precision and laboratory cleaning, always in controlled professional settings. Never use them on glass, glass-lined equipment, enamel or ceramics unless etching is intended.
Formulation guidelines
- Use the minimum effective fluoride level. More HF rarely means better cleaning — it means more etching and more risk.
- Match the inhibitor to the metal. Acid corrosion inhibitors must be validated for fluoride-containing systems and the specific alloy.
- Choose compatible packaging. HF attacks glass and many metals; use HDPE or other compatible plastics.
- Consider ammonium bifluoride. Solid ABF can be easier to handle in powder or paste products, but still forms HF in acidic solution and must be treated with the same respect. See HF vs ABF.
- Check regulations. Many jurisdictions restrict or label fluoride-containing cleaning products; consumer sale of HF-containing cleaners is restricted in several regions.
Safety: non-negotiable rules
HF is corrosive and acutely toxic. Fluoride ions penetrate skin and tissue and bind calcium and magnesium, which can cause deep tissue damage and systemic toxicity, including dangerous changes in heart rhythm, even from burns that look small.
- Dilute burns may not hurt for hours. Treat any skin contact as serious: remove contaminated clothing, rinse with plenty of water, apply calcium gluconate gel and get medical help immediately.
- Eye contact: rinse with water for at least 15 minutes and seek urgent medical care.
- Wear HF-rated PPE: splash goggles, face shield, neoprene or butyl gloves, acid-resistant apron or suit and boots.
- Work with local exhaust or good ventilation; never mix fluoride cleaners with incompatible chemicals.
- Keep calcium gluconate gel at every point of use and train staff in HF first aid.
- Collect and treat fluoride-containing rinse water — lime precipitation is common — according to local environmental rules.
- Follow the SDS; transport as dangerous goods (HF solutions: UN 1790, Class 8, subsidiary 6.1). See safe shipping and handling of HF.
FAQ
Can ammonium bifluoride replace HF in a cleaner?
In many powder, paste and some liquid acid formulations, yes — ABF provides fluoride and forms HF in acidic solution. Performance and hazard are not identical, so reformulation needs testing, and ABF must still be handled as a toxic, corrosive fluoride.
What HF concentration should I buy for formulating?
That depends on your dosing equipment, logistics and final product strength. Higher concentrations reduce freight per unit of HF but increase handling hazard; many formulators prefer 40% or 55% industrial grade. We can discuss options when you send your inquiry.
Do you supply finished cleaning products?
ANFA supplies fluoride raw materials and custom fluoride blends for industrial users. The formulator remains responsible for the final product, its labelling and local regulatory compliance.
Grades and packaging from ANFA
For cleaning formulations, industrial-grade HF is normally sufficient. ANFA manufactures industrial hydrofluoric acid to GB/T 7744 in concentrations from 30% to 70% (typically 40 / 55 / 60%), packed in 25 kg and 200 kg PE drums, 1000 L IBCs and ISO tank containers. Electronic grades are available for applications that need very high purity. Ammonium bifluoride (≥ 98.0%, EU REACH registered) and fluoroboric acid are alternatives for some formulations.
Talk to a manufacturer
ANFA Chemical (安发化工（杭州）有限公司) has manufactured inorganic fluorides in its own factory in Hangzhou since 1995 and exports dual-use controlled items under export licences; an end-user declaration may be requested. Tell us the product, grade, estimated volume, packaging and destination port: email [email protected], WhatsApp +61 493 468 903, or use our contact page. SDS, TDS and COA are provided upon inquiry confirmation.