Photogravure Process

The photogravure process was developed in the 1850s, and involves producing a photographic image from an engraving plate to create a print that has the subtlety of a photograph and the aesthetic quality of a lithograph. The process is rarely used any longer due to its labor-intensive nature. Perhaps more important, in order to acquire the knowledge and skill necessary to effectively apply the photogravure method, one must be apprenticed to an expert artisan, few of whom survive today. The process consists of taking the picture, producing a copper printing plate of the image, and printing the image on paper -- three basic steps but each one laborious and demanding of a high degree of exactitude.

First, a photographic image is created using a camera to expose film. After taking a picture, a glass positive transparency is made from the film negative. Next, a copper engraving plate that has been steel faced using electrolysis to avoid wear to the etches is dusted with grains of bitumen and heated so that the bitumen becomes attached to the plate. A carbon print that has been exposed beneath the transparency is then transferred onto the plate. The plate is bathed in warm water, which causes the unexposed gelatin of the carbon print to be washed away and leaves the image in relief. Ferric chloride then is applied to the plate and eats into the copper in proportion to the highlights and shadows of the gelatin relief. The result is an etched copper plate of the original photographic image. A photogravure plate contains etches from one to thirty microns deep that capture the entire range of tonality of the glass positive of the photograph.

Meanwhile, the paper onto which the photogravure is to be applied must be cut, uniformly dampened, and stored in that condition in order to provide the ideal printing surface. A special mixture of inks representing a sepia tone are mixed and applied to the entire face of the plate. Then the plate is wiped with a tarleton in several steps to remove excess ink and to assure that the ink covers the plate uniformly.

The production of the final photogravure print involves pressing the plate onto handmade paper. All photogravures are hand printed, using mechanized or manual Brand presses. The plate is laid in place on the press in a pre-marked position to ensure proper alignment. The pressure of the press then forces ink from the grooves in the plate onto the paper.

After each strike, the plate must be cleaned, re-inked, wiped, and again placed on the press. For each individual print, the entire process involves nearly half an hour. The combination of the chemical and mechanical processes produces an exacting image of great intimacy. Though a photogravure looks like a photograph, it is actually a series of connected lines, unlike the disconnected dots that make up a photograph.

© 2001 Southern Alleghenies Museum of Art