Photogenic Drawing 6

An experimental cyanotype of an engraving of a lady with a harp, by Sir John Herschel (1792-1871), 1842.

Herschel invented the cyanotype or 'blueprint' in 1842, employing iron salts (ferric ammonium citrate and potassium ferricyanide) which produce Prussian blue under the action of light. It was a simple process to use and required only water as a fixative.

The cyanotype was the only first-generation photographic technique to find any lasting use.

Computer-generated positive of the same image.

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