Platinotype

About

A platinum print is a one-layer monochrome process based on the light sensitivity of iron and platinum salts.

Spiromètre enregistreur destiné à mesurer par insufflation et élévation de la pression dans un récipient de 300 litres, la quantité d'air inspirée et expirée dans un acte respiratoire et à comparer les mesures avec les indications du pneumogra[phe], Marey, Etienne-Jules, 1887, 14,9 x 11,5 cm, bibliothèque de l'Hôtel de Ville

Historical period of production and use

The process was patented in 1873 by British inventor William Willis. In 1879, he founded the Platinotype Company, the first firm to market pre-coated papers, which achieved a great deal of commercial success, mainly in England and the United States. However, their popularity was cut short in the 1910s, when platinum prices soared in the lead-up to World War I.

Thanks to its aesthetic qualities and extreme stability, the platinotype process continued to be used by major photographers such as Stieglitz, Steichen, Strand, and Weston, and appears in the works of Manuel Alvarez-Bravo, Irving Penn, Mary Ellen Mark, Robert Mapplethorpe, and Isabelle Muñoz, among others.

Fabrication

In the platinotype process, a sheet of paper is coated with a mixture of ferric oxalate and potassium tetrachloroplatinate (II), then dried. The paper is exposed to sunlight for a few dozen minutes while in contact with the negative in a printing frame. When the image is developed in a bath of potassium oxalate, it dissolves the ferric oxalate and reveals the image by reducing the platinum to a metallic state. Finally, it is cleared with a solution of hydrochloric acid and then washed with water.

The images that result from this process are formed directly in the fibres of the paper (one layer process), offering a matte appearance and subtle shades of grey and shadows that can range all the way to deep black. The tone of a platinum print can be adjusted by using a warm bath to develop them or adding mercury salt to the developing solution. This produces warm blacks. The original platinotype process has given rise to numerous variations, including the palladium process, which is very similar and produces blacks with a slightly purplish-pinkish hue.

Identification

Platinum prints are characterised by their matt finish, neutral tones, wide range of grey tones and the visible paper fibres. They can be confused with matt collodion aristotypes that have been platinum-toned.

Deterioration

This process is chemically very stable. The paper, however, may yellow due to the oxidation of the cellulose and may suffer mechanical damage (creases and tears at the edges). Platinum prints, when stored in portfolios or albums, can oxidise the opposite page and cause the image to transfer onto it, creating a ‘ghost image’.

Credits

Visual Glossary of Photographic Processes © ARCP / Mairie de Paris, 2023

Glossary

Albumen Print

Aristotype

Autochrome

Carbon Print

Chromogenic Prints

Collodion Glass Plate Negative

Portrait Crayon

Cyanotype