DAS (diazidostilbene)
CAS 2718-90-3 · EC 220-316-4 · C14H8N6Na2O6S2
Also known as disodium 4,4'-diazidostilbene-2,2'-disulphonate, 4,4'-diazido-2,2'-stilbenedisulfonic acid disodium salt
In alt-process usage "DAS" = diazidostilbene (CAS 2718-90-3). Only one C&L notification exists (Warning, H228, H332, H312, H302) – very low evidence base.
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: 100.0% of notifications, 1 distinct classifications notified.
Signal word: Warning
Flammable · Harmful or irritant
- H228 Flammable solid.
- H332 Harmful if inhaled.
- H312 Harmful in contact with skin.
- H302 Harmful if swallowed.
Photographic uses
- dichromate-free sensitiser for carbon transfer and casein printing; practitioners report poor results in true gum printing
Sources
- ECHA CHEM substance record: Disodium 4,4'-diazidostilbene-2,2'-disulphonate (100.018.470)
- 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)
- Sensitizers in Carbon Transfer Printing: What to Know
- Using DAS to replace Potassium Dichromate in the Gum Bichromate process (forum thread)
Checked October 2026.