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Sidero-Cupreatype / Colouring Tannic acid - bleach

REF #60

Grey brown Grey yellow Brown

Ferric Ammonium Citrate [NH4]{y}[Fe{x}(C6H4O7)] sol. 20%

Potassium Ferricyanid K3[Fe(CN)6] sol. 8%

Ammonium copper citrate (NH₄)₂Cu(C₆H₅O₇)₂ sol. 20%

Bleach NaOCl sol. 3.7%

Tannic acid C76H52O46 sol. 7%

365nm

Operating procedure

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

Consignes de sécurité

Corrosive product: Handle with nitrile gloves and safety goggles.

Beware of bleach vapours. Never mix with a base.