Ammonium iron(III) oxalate trihydrate
CAS 13268-42-3 · EC 603-647-2
Also known as ammonium ferric oxalate, ammonium ferrioxalate, triammonium tris(oxalato)ferrate
Whether the UK reportable "metallic oxalates" poison entry applies to this mixed ammonium/iron salt was not determined.
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
There is no official EU classification. Shown is the classification most companies have notified to ECHA: 88.68% of notifications, 3 distinct classifications notified.
Signal word: Warning
Harmful or irritant
- H312 Harmful in contact with skin.
- H302 Harmful if swallowed.
Photographic uses
- new cyanotype sensitiser (Ware)
- platinum/palladium sensitiser
Used in: New cyanotype (Mike Ware)
Sources
- ECHA CHEM substance record: Ethanedioic acid, ammonium iron(3+) salt (3:3:1), trihydrate (100.106.935)
- ECHA CHEM – C&L Inventory (harmonised CLP Annex VI and notified classifications) and legal obligations (chem.echa.europa.eu APIs: /api-cnl-inventory/harmonized|industry, /api-obligation-substance/v1)
Checked October 2026.