Glossary
The words of alternative photography
A short, honest dictionary of the processes, chemistry and gestures behind non-toxic alternative printing.
- Aquaprint
- Vision Picturale’s reformulation of gum bichromate, dichromate-free (N°03 sensitizer). Same Pictorialist look — matte surface, pigment grain, layers — without any CMR salt.
- Bichromate / Dichromate
- Salt (potassium or ammonium) that makes gelatin or gum light-sensitive. The hexavalent chromium it contains is classified CMR (carcinogenic, mutagenic). It is the shared toxic point of historical gum, carbon, bromoil and resinotype.
- Bromoil
- Process (1907) in which a gelatin matrix is inked by hand, with a brush, using greasy ink. In its classic form the matrix is obtained by bleaching a silver print in a bichromate bath.
- Carbon print
- Pigment process (Poitevin, 1855) in which a gelatin loaded with carbon pigment is sensitized with dichromate, exposed and developed in water. It is the most permanent print in photography.
- CMR
- Carcinogenic, Mutagenic, Reprotoxic — the classification of the most hazardous substances for health. The dichromate used in historical pigment processes is classified CMR.
- Cyanotype
- Iron-based process (Herschel, 1842) producing a Prussian blue, developed in water. Low-toxicity from the start, it is the gateway to alternative photography.
- Water development
- Step where the image appears through plain washing: areas not hardened by light dissolve, exposed areas remain. Specific to pigment processes (gum, carbon).
- Gelatin
- Binder that carries the pigment and hardens under light once sensitized. Vision Picturale uses its N°05 gelatin for carbon, bromoil and resinotype.
- Gum bichromate
- Pigment process (Poitevin 1855, revealed by Demachy in the 1890s) mixing pigment, gum arabic and dichromate. A drawing-like, painterly look. Reformulated dichromate-free by Vision Picturale as Aquaprint.
- Exposure
- Exposing the sensitized paper to UV, through a negative, until the latent image forms. In sunlight or under a UV unit such as the Luminograph.
- Digital negative
- A negative printed on transparency from a file, placed in contact with the paper for exposure. It replaces the large-format film negative.
- Permanence (archival)
- A print’s ability to resist degradation over time. Pigment processes (carbon, gum) are among the most permanent, because the pigment is chemically inert.
- Pictorialism
- Movement (late 19th–early 20th c.) that claimed photography as art through hand processes (gum, carbon, bromoil) yielding images close to drawing or painting.
- Pigment
- Powdered colouring matter that forms the image in pigment processes. Inert and stable, it ensures the print’s permanence (unlike silver or dyes).
- Pigment process
- Family of processes where the image is made of pigment held in a binder hardened by light (gum, carbon, bromoil, resinotype). Historically sensitized with dichromate.
- Four-colour
- Colour gum obtained by superimposing several pigmented passes (cyan, magenta, yellow, black). Vision Picturale practises it dichromate-free.
- Resinotype
- Pigment process (Namias, 1920s) that seals the pigment in a hardened resin: a vitrified print, halfway between photograph and enamel. Vision Picturale version without dichromate or solvent.
- Sanguine
- A gum variant in red-brown pigment, evoking the red chalk of Old Master drawings. Made famous by Demachy’s red gums.
- Sensitizer
- Agent that makes a support light-sensitive. Where historical processes used dichromate (CMR), Vision Picturale uses its N°03, dichromate-free.
- UV (radiation)
- Ultraviolet radiation that drives the exposure of alternative processes. Provided by the sun or a dedicated UV unit (Luminograph).