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Sidero-Cupreatype / Bleaching with caustic soda

REF #65

Greyish blue Pearl White Pink Pale Lavender Lavender White Taupe

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%

Caustic soda NaOH sol. 0.1%

365nm

Operating procedure

Used for recolouring behind, particularly with tannins.

Make a normal sidero-cupreatype (sheet #3) with:
- 10 minutes exposure
- 30+30 seconds rinsing
Diluted soda bath for 10 seconds
Washing 30+30+30 seconds

Consignes de sécurité

Corrosive product: Handle with nitrile gloves and safety goggles.

Be very careful when handling lye, as it is highly corrosive and extremely dangerous to mucous membranes. Start with a product that is already diluted, such as Destop (10%).