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Cyanotype / CuSO4 toning

Cyanotype / CuSO4 toning

REF #41
Greyish blue Medium grey Grey brown Navy blue Grey green Tan / Sable Pinkish beige
Potassium Ferricyanid K3[Fe(CN)6] sol. 8%
1
Ferric Ammonium Citrate [NH4]{y}[Fe{x}(C6H4O7)] sol. 20%
1
Copper sulfate CuSO4 sol. 20%
365nm

Operating procedure

1. Make a basic cyanotype (5 min), but limit rinsing to 10 seconds, do not dry.
2. CuSO₄ bath for 30 seconds.
3. Wash three times for 30 seconds.

Incomplete washing allows copper ferricyanide to form (copper-brown shadow).