Carbon Print

About

The carbon print process is a technique based on the photosensitivity of the potassium bichromate mixed with gelatin. The carbon processes belong to the pigment techniques of photography, where the photosensitive element is the binder of the image and not its components.

Braun A., Spectacle de la folie humaine, 1900, reproduction d'un talbeau de Glaize conservé au musée d'Arras, collection didactique D3P. ©Agathe Calmanovic-Plescoff/D3P/Ville de Paris

Historical period of production and use

In the 19^th century it was the most popular pigment printing process.Carbon prints were invented in 1855 by Louis-Alphonse Poitevin, who had made use of existing research into insolubilization under light of bichromatic colloids – gelatin in this case. It represented an important breakthrough in the search for stable photographic processes (‘duc de Luynes contest’). By the end of the 19^th century, " non-transfer carbon" prints, known as "direct carbon", were also available on the market until the 1950’s, such as Artigue “charbon-velours and Fresson “charbon-satin” (see notice). The images produced using these techniques, which are smoother and more textured, are well suited to the Pictorialist movement.

Manufacturing

A sheet of paper is coated with a mix of bichromated gelatin and pigment. It is then dried in darkness before being exposed to light in contact with a negative. The image obtained is stripped in warm water: areas exposed to light are hardened and become insoluble, whilst in areas that have not been exposed, the gelatin and the pigments dissolve in the water, leaving the paper visible. The Poitevin's invention does not allow the accurate reproduction of mid tones, that are carried out with their pigments into the water bath. Various improvements to the process were therefore made over time, including the carbon transfer print invented in 1860: in this process, the image layer is removed from its original support before being transferred to a second support. To tackle the problem of the image being reversed during a single transfer, photographers then developed the double transfer technique, which allowed them to reproduce the natural sense of the subject. During this same period, commercialisation of pigmented paper began and the choice of pigments grew, as for example, sienna, indigo, Prussian blue and sepia. In France, the Alsacian photographer Braun is one of the major users of this process, whilst in England it is Swann.

Identification

Prints can have a bright or satin finish. Depending on the nature of the pigments used, the process can produce images with a wide range of tones. The most popular hues/tones used were chocolate or purplish brown or black charcoal.

Deterioration

Since the pigment that makes up the image is stable, the carbon print process offers excellent permanence, just like other pigment-based photographic techniques. The process is also known as “permanent photography.”

Détail agrandi x 8 © Reproduction : ARCP / Mairie de Paris

Credits

Visual Glossary of Photographic Techniques © ARCP / Mairie de Paris, 2014

Glossary