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Sidero-Cupreatype / Colouring Tannic acid - Na2CO3

Sidero-Cupreatype / Colouring Tannic acid - Na2CO3

REF #58
Grey brown Brown Tan / Sable
Ferric Ammonium Citrate [NH4]{y}[Fe{x}(C6H4O7)] sol. 20%
1
Potassium Ferricyanid K3[Fe(CN)6] sol. 8%
2
Ammonium copper citrate (NH₄)₂Cu(C₆H₅O₇)₂ sol. 20%
1
Sodium carbonate Na2CO3 sol. 10%
Tannic acid C76H52O46 sol. 7%
365nm

Operating procedure

Make a normal sidero-cupreatype (sheet #3) with:
- 6 minutes exposure
- 30+30 seconds rinsing
Na2CO3 bath for 1 minute
30+30 seconds washing
Tannic acid bath for 1 minute
30+30+30 seconds washing