Photochrome

Manufacturing

Several lithographic stones are produced, one for each colour (this quantity may vary depending on the final rendering required), by coating them with bitumen of Judea. The stone is placed in contact with the negative and exposed to sunlight, which selectively insolubilizes the bitumen. The unbleached bitumen, which remains soluble, is removed in a bath of turpentine and then water. The stones are then etched with acid and tinted with ink. The print is produced on high-quality, smooth postcard sized paper. This technique leaves a great deal of scope for the creativity and interpretation of the person producing the work, enabling him/her to accentuate contrast and tonality.

Identification

This technique leaves a great deal of scope for the creativity and interpretation of the person producing the work, enabling him/her to accentuate contrast and tonality.Postcards or larger-format prints usually bear the inscription ‘P.Z’ or ‘photochrome’, which makes them easy to identify. The paper used is coated with a white receptacle layer that conceals the paper fibres. The inks used are dense and intense.

Deterioration

Photochromes are highly stable as they are photomechanical prints whose images are composed of pigments. The paper may yellow due to the oxidation of cellulose and may suffer mechanical damage (creases and tears at the edges).

Today, photochrom prints feature in numerous collections, including in that of the Bibliothèque Historique de la Ville de Paris and the Bibliothèque Forney in Paris, the Musée suisse de l’appareil photographique in Vevey, the Whitney Museum in New York, and the Library of Congress in Washington.

Glossary