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The Photogravure Printing Process

What is a Photogravure?

A photogravure is a photographic image produced from an engraving plate. The process is rarely used today due to the costs involved, but it produces prints which have the subtlety of a photograph and the art quality of a lithograph. In essence, the production of a photogravure consists of three steps: taking the picture; producing a printing plate of the image; and printing the image on paper.

The basic process, also called photogravure, was developed in the 1850s. After taking a picture, a glass transparency is made from the negative. Next, a copper engraving plate is dusted with grains of bitumen and heated so that the bitumen becomes attached to the plate. A carbon print which has been exposed beneath the transparency is then transferred to the plate. The plate is then bathed in warm water which causes the unexposed gelatin of the carbon print to be washed away, leaving the image in relief. Ferric chloride is then 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.

The final step, printing, involves spreading ink evenly across the plate and then pressing the plate onto the paper. The combination of the chemical and mechanical process produces an image both warm and precise. A photogravure looks like a photograph but is a series of connected lines, rather than unconnected dots as in a photograph. The rich sepia ink and handmade paper used for the Curtis photogravures are the final elements in the production of the beautiful art prints of The North American Indian.

Deli Sacilotto, Printer

STEEL FACING - A copper plate must be steel faced to avoid wear to the etches. The process uses electrolysis to apply the facing.

PREPARING THE PAPER - The paper must be cut, uniformly dampened, and stored in that condition in order to provide the ideal printing surface.

INKING THE PLATE - A special mixture of inks, representing a sepia tone, are mixed and applied to the entire face of the plate.

WIPING THE PLATE - The plate is wiped with a tarleton in several steps to remove excess ink and assure that the ink has been applied uniformly.

THE FINISHED PLATE - A photogravure plate contains etches from one to thirty microns deep in order to capture the entire tonality of the glass positive of the photograph.

PLACING THE PLATE ON THE PRESS - All photogravures are hand printed, using mechanized or manual Brand presses. The plate is laid in place on the press in a premarked position to insure proper alignment.

PLACING THE PAPER ON THE PLATE - The photogravure process is one in which ink from the plate is forced from the grooves onto the paper by the pressure of the press.

FINISHED GRAVURE - The entire process takes nearly twenty minutes to complete as after each strike, the plate must be cleaned, re-inked, wiped, and again placed on the press.