Cyanotype / CuSO4-Na2S toning

Cyanotype / CuSO4-Na2S toning

REF #42
Potassium Ferricyanid K3[Fe(CN)6] sol. 8%
1
Ferric Ammonium Citrate [NH4]{y}[Fe{x}(C6H4O7)] sol. 20%
1
Sodium sulfide Na2S · 9 H2O sol. 2%
Copper sulfate CuSO4 sol. 20%

Operating procedure

1. Make a basic cyanotype (5 min), with 10+10s rinsing, do not dry
2. CuSO4 bath for 30s
3. Rinse for 30 seconds
4. Na2S bath for 10s -> deep black (FeS)
5. Rinse for 30 seconds -> becomes grey-black

After several days, turns brown-yellow