Cyanotype / CuSO4 - Vitamin C toning

Cyanotype / CuSO4 - Vitamin C toning

REF #47
Potassium Ferricyanid K3[Fe(CN)6] sol. 8%
1
Ferric Ammonium Citrate [NH4]{y}[Fe{x}(C6H4O7)] sol. 20%
1
Copper sulfate CuSO4 sol. 1.1%
Ascorbic acid C6H8O6 sol. 0.4%

Operating procedure

1. Make a basic cyanotype (7 min), with 3 min rinsing, do not dry.
2. CuSO₄ bath for 7 min.
3. Wash for 10 s (stop as soon as copper hydroxide appears).
4. Ascorbic acid bath for 1.5 min.
5. Wash for 2 min.