Hydrofluoric acid: what every new analyst must be told
HF burns can be painless for hours while fluoride moves toward bone. Preparation matters more than reaction time.
Hydrofluoric acid is not simply a strong acid - in fact it is a weak one. The hazard is the fluoride ion, which penetrates skin and binds calcium and magnesium in tissue and bone. A dilute splash can be painless at first and life-threatening later.
Before the bottle is opened
- Calcium gluconate 2.5% gel, in date, on the bench - not in a store cupboard.
- Nitrile gloves are not enough on their own. Use heavy nitrile or neoprene gauntlets over an inner glove, plus a face shield over goggles.
- Work in a fume hood with the sash low. Never at an open bench.
- Nobody works with HF alone. Somebody else must know it is happening.
Labware
Glass is the wrong material - HF dissolves it and the reaction consumes your acid and contaminates your sample. Use PTFE, PFA or polypropylene throughout, including your waste container.
If there is a splash
- Flush with water for five minutes.
- Apply calcium gluconate gel and keep massaging it in.
- Go to hospital, even if it does not hurt. Take the safety data sheet with you.
- Tell the clinician it is hydrofluoric acid - treatment differs completely from other acid burns.
Concentrated HF exposure over roughly 2% of body surface area can be fatal from systemic hypocalcaemia. Treat every splash as significant.
Waste and spills
Neutralise small spills with a purpose-made HF absorbent containing calcium, which converts the fluoride into insoluble calcium fluoride. Ordinary sand or vermiculite absorbs the liquid but leaves the fluoride chemically available.
This note is a summary, not a substitute for the safety data sheet or your local risk assessment.