Three Color Cyanotype Toning


Chem:
20% AFC
8% Ferricyanide
(Normal Cyanotype exposure is 12 minutes.)
Vinegar
H2O2 (optional)
Soda Ash (Super Washing Soda)
Green Tea
Corn Starch (or Arrowroot)

Negatives:
Split RGB channels normally, apply Clay Harmon’s old RatioCurve (from https://www.alternativephotography.com/digital-negatives-color-ratio/), invert, flip canvas, and screen with a R27/G141/B27 color fill
(Color fills and exposure times may vary.)

Paper:
Preshrink and Size paper with 3.5% starch

Printing:
Lilac (Magenta):
Mix 1A : 1B
12minutes exposure
Bleach 5 Minute in 5% soda ash, wash 5 minutes, acidify 1 minute in 1% acetic acid, rinse*
Tone 10minutes in Green tea (or until paper begins to stain), wash 10 minutes, then bleach 5 minutes in 5% soda ash

Ochre (Yellow):
Mix 1A : 1B
(The emulsion reacts with the tannin under coat and will appear fogged; this will clear.)
18 Minute exposure
Wash, then acidify in 1% acetic acid, wash*
Bleach 5 minutes in 5% soda ash

Cyan:
Mix 2 parts A : 2 parts B : 3 parts H20
8 Minutes Exposure


*These steps are optional but help to minimize paper staining and keep highlights clear.

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