photogravure

photogravure

[foh-tuh-gruh-vyoor, -grey-vyer]
photogravure: see printing.

Photogravure is an intaglio printmaking process initially developed in the 1830s by Henry Fox Talbot in England and Nicéphore Niépce in France. These early images were among the first photographs, pre-dating daguerreotypes and the later wet-collodian photographic processes. Fox Talbot worked on extending the process in the 1850s and patented it in 1852 ('photographic engraving') and 1858 ('photoglyphic engraving'). Photogravure in its mature form was developed in 1878 by Czech painter Karel Klíč. This process, the one still 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 photo-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 the French term 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 wells are varied in a photogravure plate and are often blended into a smooth tone by the printing process. Photogravure practitioners such as Peter Henry Emerson and others brought the art to a very high standard of expression in the late 19th century. This continued with the work of Alfred Stieglitz in the early 20th century, especially in relation to his publication Camera Work. This publication also featured the photogravures of Alvin Langdon Coburn who was a fine gravure printer and envisioned his photographic work as gravures rather than other photo-based processes. The speed and convenience of silver-gelatin photography eventually displaced photogravure which fell into disuse after the Edward S. Curtis gravures in the 1920s. One of the last major portfolios of fine art photogravures was Paul Strand's 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 only several dozen workshops around the world.

Creating the plate

In order to make a photogravure plate of a photographic image, one must go through several distinct stages. First, a continuous tone film positive is made from the original photographic negative. One can enlarge a smaller negative onto a sheet of film which is then processed to a range of continuous tones with specific densities. The second stage is to sensitize a sheet of pigmented gelatin tissue (now only made by the Autotype Company) by immersion into a 3.5% solution of potassium dichromate for 3 minutes. Once dried against a Plexiglas (Perspex) surface, it is ready for the next stage. The third stage (usually the next day) is to expose the film positive to the sensitized gravure tissue. The positive is placed on top of the sensitized sheet of pigmented gelatin tissue. 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 usually before the exposed gelatin tissue is adhered to the plate. The UV light travels through the positive and screen (if used) in succession, each time hardening the gelatin in proportion to the degree of light exposed to it. The fourth stage is to adhere the exposed tissue to the copper plate. The gelatin tissue is adhered or "laid down" onto the highly polished copper plate under a layer of cool water. It is squeegeed into place and the excess water is wiped clear. Once adhered, the fifth stage is to use a hot water bath to remove the paper backing and to wash away the softer, unexposed gelatin. The remaining depth of hardened gelatin is relative to the exposure. This layer of hardened gelatin forms a contoured resist on the copper plate. The resist is dried, the edges and back of the copper are stopped out (staged). The sixth stage is to etch the plate 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 gelatin, etching the shadows and blacks under the thinest areas first. The etching progresses through the tonal scale from dark to light as the plate is moved to successively more dilute baths of ferric chloride. The image is etched onto the copperplate by the ferric chloride, creating a gravure plate with tiny wells of varying depth to hold ink. 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. The final stage is to print the cleaned plate.

Printing the plate

Printing a photogravure is similar to printing any other intaglio plate, especially a finely etched aquatint. A stiff, oily intaglio printing ink is applied to the whole surface of the plate with a rubber brayer, or a small, stiff squeegee, or a rolled tamper. The plate is then gently wiped with tarlatans to remove the excess ink and drive it into the recesses (wells). It is finally wiped with the fatty part of the palm of the hand in quick glancing strokes. This removes all remaining ink from the polished highlights and high points and leaves ink only in the etched recesses. After the edges are cleaned, the plate is placed on the printing bed of an intaglio press. It is covered with a sheet of dampened rag paper and then two to three layers of thin wool blankets. It is then run through the press at high pressure. The high pressure pushes the fibers of the dampened paper into the wells of the plate which then transfers the ink onto the paper thereby creating the impression. The paper is carefully peeled off the plate and placed between blotters and weighted so it will dry flat. The plate can now be re-inked for another impression or it can be cleaned for storage.

Photogravure today

Photogravure continues to be used by fine printmakers. The experimental print lab Graphicstudio is a contemporary facility renowned for its very fine photogravures.

External links

Further reading

Focal Press: Copper Plate Photogravure (2003) by David Morrish and Marlene MacCallum

References

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