Sodium metabisulfite
CAS 7681-57-4 · EC 231-673-0
Also known as disodium disulphite, sodium pyrosulfite
Handle chemistry safely
Wear gloves and eye protection, work with good ventilation, and read the supplier’s safety data sheet before use. Hazard information here is a summary, not a replacement for it. Dispose of all photographic chemistry correctly, in line with local laws and your local authority’s guidance. Never mix waste solutions, and check the supplier’s safety data sheet before disposing of anything.
Hazards
Official EU classification (harmonised under CLP Annex VI).
Signal word: Danger
Harmful or irritant · Corrosive
- H302 Harmful if swallowed.
- H318 Causes serious eye damage.
- EUH031 Contact with acids liberates toxic gas.
Photographic uses
- preservative (Pyrocat-HD per some versions)
- acidifier in fixers/stock solutions