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 several dozen workshops around the world. Contemporary artists working in the medium include Sama Alshaibi. Qualities Photogravure registers a wide variety of tones, through the transfer of etching ink from an etched copper plate 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 vary the size of dot, the depth of ink wells is varied in a photogravure plate. The human eye resolves these fine variations into a continuous tone image. Photogravure is distinguished from rotogravure in that photogravure uses a flat copper plate 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. In French, the correct term for photogravure is , while the French term refers to any photo-based etching technique. Technique Photogravure plates go through several distinct stages: First, a continuous tone film positive is made from the original photographic negative. A smaller negative can be enlarged 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 by immersion into a 3.5% solution of potassium dichromate for 3 minutes. Once dried against an acrylic (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.