Gelatin Silver Bromide Print

Gelatin silver bromide negatives on glass and film

The first monochrome emulsions using gelatin silver bromide were introduced in 1871, following the discoveries of R. L. Maddox. The purpose of this research was to produce negatives that could be used in dry form, thereby overcoming the major drawback of wet collodion negatives (see notice). The combination of gelatin and silver bromide makes it possible to effectively harness the potential of the latent image and to produce emulsions that offer the double advantage of being prepared in advance and highly sensitive - unlike dry collodion processes. The vast possibilities opened up by this technology and its ease of use for photographers immediately resulted immediately in an industrial production, the marketing of lightweight cameras that were easy to carry and use, and ultimately the development of an unprecedented market for both amateurs and professionals.

Gelatin-silver bromide negatives on glass, which remained on the market until the 1950s, were soon joined by - and eventually supplanted by - negatives on flexible plastic substrates (see notice).

Louise Conrad gagnante de la catégorie dames lors du Critérium cycliste des porteurs de journaux, Agence Rol, 8 février 1931, Paris, 17,8 x 12.1 cm, musée Carnavalet, Histoire de Paris

Gelatin silver chloride prints

The use of gelatin silver developing out technology for positive prints on paper begun only during the 1880s, due to because photographers tend to use printed-out papers (albumine papers or aristotypes), which fully met their needs. The first developed papers used silver chloride (Eder and Pizzighelli, 1881) and were manufactured on baryta paper. With even lower sensitivity, they did not allow for enlargement and were printed by contact under town gas light rather than sunlight, as was the case with printed-out papers, hence their name “gaslight” paper.

Although their natural tone is a neutral black, chemically developed prints can have several different tones depending on the type of developer, or by toning. Sepia toning (sulfur toning), which was the most popular, from the 1910s onward produces chocolate brown shades and a high stability to the silver image., Other, rarer toning methods, such as platinum or selenium, were also used.

The advantage of this process lies in its highly nuanced rendering of halftones and the resulting excellent image resolution. The most common brand names are Kodak’s Velox® papers (very often used in postcard photography) and Gevaert’s Ridax® papers. This type of technology is often associated with high-quality production - either professional work in portrait studios or amateur photography linked to the rise of middle-class tourism in the early 20^th century. This process coexisted with the more sensitive silver bromide gelatin paper, but it gradually fell out of use in the 1950s as the practice of enlarging photographs became widespread.

Gelatin silver bromide prints

Silver bromide halide salts are particularly light-sensitive and allow for enlargement, unlike silver chloride. This practice, however, only gradually became established during the 20^th century. Gelatin-silver bromide paper gradually gained prominence following the reduction in negatives’ formats and, in particular, the introduction of the 24x36 mm format offered with Leica cameras (1925), eventually replacing gaslight papers entirely from the 1950s onward.

Silver bromide gelatin prints were first produced on baryta papers with various textures and finishes (glossy, satin, matte, tinted, etc.). During the 1950s, optical brighteners - identifiable by the bluish fluorescence observed under ultraviolet lamp - were introduced into the papers to enhance their brightness and whiteness.

From the end of the 1960s, manufacturers introduced plastic papers (known as RC for Resin Coated) in order to reduce the processing and drying time as well as to allow mechanization using machinery, thereby enabling the production of press photographs for publication in newspapers to be speeded up. The paper subtract enveloped by two layers of polyethylene, the image layer loaded with white pigment (titanium dioxide), just like the baryta layer.

Silver bromide paper was the most commonly used process in the 20^th century, and although still marketed, it is gradually becoming obsolete since the emergence of digital monochrome prints in the early 21^st century.

Identification

The three types of silver-based developable papers are difficult to distinguish from one another visually. All three are characterised by a neutral black image tone, in contrast to direct blackening processes, which produce warmer tones. Silver is prone to oxidising, creating a ‘silver mirror’ effect in the deep black areas of the image, and to sulphurisation, taking on a brownish tint, if fixer residues are still present (due to faulty fixing or washing).

Deterioration

Developing-out processes are generally more stable than printed-out processes when it comes to climatic conditions, pollutants, or light. This characteristic is due to the microscopic structure of silver, which forms large clusters’ filaments that are relatively resistant to external degrading agents. Their main vulnerability lies in the hygroscopic nature of the gelatin binder, water (in liquid or vapor form), which can weaken the image layer and carry pollutants into it (resulting in silver mirroring). Improper laboratory processing (exhausted fixer, insufficient washing time) can cause partial or total sulfuration of the print. Early RC papers had stability issues (yellowing, cracking).

Credits

Visual Glossary of Photographic Processes © ARCP / Mairie de Paris, Jean-Philippe Boiteux

Glossary

Albumen Print

Aristotype

Autochrome

Carbon Print

Chromogenic Prints

Collodion Glass Plate Negative

Portrait Crayon

Cyanotype