Photochrom printing was invented in the 1880s by Hans Jacob Schmid (1856-1924), a lithographer for the Swiss publishing company Orell Füssli & Cie. It was Orell Füssli that registered the patent for it on 4 January 1888, and marketed it via its new subsidiary Photochrom Zurich – which became Photoglob Zurich in 1895 – the initials of which, PZ, appear in gold letters on the images produced in Europe. The process, which won a gold medal at the Universal Exhibition in Paris in 1889, was exported to the United States by the Photochrom Company of Detroit, but declined steadily and disappeared completely in the 1930s with the appearance of the first colour films.
A photochrom print, obtained using a black-and-white photographic negative, is based on the colour lithographic process. To create it, a number of lithographic stones are produced, one for each colour; this quantity may vary depending on the final rendering required. These stones are coated with bitumen of Judea which, once exposed to daylight through a negative, hardens and renders the areas exposed to light insoluble. The stones are then developed using turpentine and subsequently rinsed with water to remove the non-exposed sections, which have remained soluble. They are then etched with acid. The inks prepared by the printer are finally applied to each of the stones, to achieve a transfer onto smooth high quality 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.
The subjects covered are most frequently well-known views, great monuments and even important events. Those who employed this technique included the French photographer Félix Bonfils, the British photographer Francis Frith and the American photographer William Henry Jackson.
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.