Photogravure

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Photogravure of Victor Hugo, 1883

Photogravure is a type of intaglio printmaking initially developed in the 1830s by Henry Fox Talbot in England and Nicéphore Niépce in France. These were the first photographs, pre-dating daguerreotypes and the later silver-gelatin photos. Photogravure in its mature form was developed in 1879 by Karl Klič (Karel Klitsch)(1841-1926) of the Czech Republic, then Arnau. This process, the one in use today, is called the Talbot-Klič process. Photogravure was developed to provide an archivally permanent way of reproducing a photographic image. Because of its high quality and richness, photogravure was used for both original fine art prints and for reproduction of works from other media such as paintings. Photogravure is distinguished from rotogravure in that photogravure uses a flat copperplate etched rather deeply and printed by hand, while in rotogravure, as the name implies, a rotary cylinder is only lightly etched, and it is a factory printing process for newspapers, magazines, and packaging. Due to an unfortunate confusion of terms, searches for "photogravure" on the web often turn up industrial machinery designed for rotogravure. In France the correct term for photogravure is héliogravure, while photogravure refers to any photo-based etching technique.

Photogravure registers an extraordinary variety of tones, through the transfer of etching ink from an etched copperplate to special dampened paper run through an etching press. The unique tonal range comes from photogravure's variable depth of etch, that is, the shadows are etched many times deeper than the highlights. Unlike half-tone processes which merely vary the size of dots, the actual quantity and depth of ink in a photogravure etching are varied. Photogravure practitioners such as Peter Henry Emerson and others brought the art to a very high standard of expression in the late 19th century, which continued with the work of Alfred Stieglitz in the early 20th century, especially in relation to his publication Camera Work which also featured the photogravures of Alvin Langdon Coburn who also was a fine gravure printer. But the speed and convenience of silver-gelatin photography eventually displaced photogravure, which fell into disuse after the Curtis gravures in the 1920s. One of the last major portfolios of fine art photogravure was Paul Strands Photographs from Mexico from 1940, reissued as The Mexican Portfolio in 1967 by DeCapo Press. Many years later, photogravure has experienced a revival in the hands of Aperture and Jon Goodman, who studied it in Europe. Photogravure is now actively practiced in several dozen workshops around the world.

[edit] Engraving

A continuous tone film positive is made from the original photographic negative. This positive is placed on top of a sheet of gelatin tissue which has been sensitized with potassium dichromate. The sandwich is then exposed to ultraviolet (UV) light. A separate exposure to a very fine stochastic or hard-dot mezzotint screen is made, or alternatively an aquatint grain of asphaltum or rosin is applied and fused to the copperplate. The UV light travels through the positive and screen in succession, each time hardening the gelatin in proportion to the degree of light exposed to it. The gelatin tissue is adhered to or "laid down" onto the highly polished copper plate. Once adhered, a hot water bath allows the paper backing to be removed and washes away the softer gelatin (relative to the exposure), forming a resist on the copper plate. The resist is dried, the edges and back of the copper is stopped out (staged), then it is etched in a series of ferric chloride baths, from the densest to slightly more dilute in steps. The density of these baths is measured in degrees Baumé. The ferric chloride migrates through the gelatine, etching the shadows and blacks under the thinest areas first. The etching progresses through the tonal scale from dark to light as you move the plate to successively more dilute baths of ferric chloride. Thus the image gets etched onto the copperplate by the ferric chloride, creating a gravure plate. The pattern formed by the aquatint grain or the screen exposure creates minute lands around which the etching occurs, giving the copperplate the tooth to hold ink. The wells which hold the ink vary in depth, a unique aspect of photogravure.

[edit] Printing

Ink is applied to the whole surface of the plate with a brayer or tamper. The plate is then wiped with tarlatans to remove the excess ink and drive it into the recesses. It is then wiped by hand thereby removing all ink from the polished highlights and leaving ink only in the recesses. The plate is then run through an intaglio press by placing a sheet of dampened rag paper under felt blankets. The high pressure then transfers the ink from the recesses of the plate into the paper, creating the impression.