AT ITS ORGIN, photography was intimately linked with printmaking. Some folks had been experimenting with light-sensitive materials since the 1810s. Their efforts were motivated by the desire to make stable fixed images directly from nature, or to make "etchings by light."
Photogravure is not a purely photographic medium. Photogravure is a chameleon, encompassing many manifestations of printmaking using a variety of darkroom and etching techniques, and is therefore hard to classify.
It often surprises people that the inventor of photography on paper, William Henry Fox Talbot, was also the father of photogravure... For Talbot, photogravure had been the logical evolution of his original invention of photography; transforming nature's sketches into permanent and beautiful printer's ink.
In photogravure, the fragile silver salts of normal photography are transcribed in the photogravure process with printing ink. This process adds to an appreciated esthetic improvement, the tonal and tactile qualities and the guarantee of absolute permanence. These values have always been recognized as famous photographers of the early 1900's such as Alfred Stieglitz, Edward Steichen, and Paul Strand adopted photogravure with enthusiasm in Camera Notes and Camera Work. It ceased being used after the Second World War because of its cost. It is only recently that a few workshops have revived this old and marvelous process.
"The quality of touch in it's deepest living sense is inherent in my photographs. When that sense of touch is lost, the heartbeat of the photograph is extinct- dead. My interest is in the living" ~ALFRED STIEGLITZ FROM TWICE A YEAR 1938
I recently attended a three day intensive workshop in copper plate Photogravure, thus demystifying the process for me. We started out with an 8"x10" positive image (obtained from a digital image file or scanned negative) on transparency film and used photoshop and a printer to do this. After our image was printed out as a positive, we were ready to begin the very elegant, artful process.
THE FIRST STEP in making a photogravure print is preparing the printing plate. This pure copper plate must be thoroughly cleaned, its surface highly polished, and its edges beveled (to avoid damaging the paper during printing).
WHILE THE PLATE IS BEING READIED, the image is also prepared. A positive transparency is made from either an original negative or a copy negative. This film positive, which must be made the size desired for the final print, is then contact-printed under ultraviolet light to a gelatin-coated paper (known as carbon tissue) which was previously made light sensitive by soaking it in a solution of potassium bichromate, then dried. In this process, the action of the light through the film positive changes the melting temperature of the gelatin. Areas exposed to light have a higher melting temperature and are said to be "hardened" and less exposed areas stay the same.
NEXT THE IMAGE must be transferred to the prepared copper plate. The image-carrying tissue is adhered to the plate. This tissue/plate is then soaked in hot water softening the gelatin and allowing the paper base of the tissue to separate. Portions of the gelatin that received little or no light during exposure to the transparency remain soluble and slowly wash away, leaving a gelatin image that will act as an acid resist when the plate is etched. The gelatin image on the copper plate, now called a resist, is then dried.
NEXT THE PLATE IS placed in a succession of etching baths. Etching begins in sequence in proportion to the thickness of the gelatin coating and the viscosity of the mordant (Ferric Chloride) bath. The viscosity of the Ferric Chloride controls the speed with which the solution penetrates the gelatin. The result is a plate with many minute reservoirs or cells of varying depths. During printing, the deeper cells hold more ink and thus transfer more ink to the paper, creating the darker areas of the image
FINALLY, AFTER THE PLATE has been thoroughly washed, the gravure is printed - on an etching press, like all other forms of intaglio printing. Stiff ink is spread over the entire plate and worked into the recessed areas that form the image. The plate is then positioned face-up on an etching press. The artist places a piece of dampened, high-quality paper over the plate then covers the paper with etching felts for padding and passes this through the press. The rollers force the paper into the small depressions that hold the ink, creating a printed image. To make the next impression, the artist re-inks the plate and repeats the process. At the end of the printing session, the plate is thoroughly cleaned.
This procedure produces "grain" gravures, so called because of the random dots created by the dusted rosin. Photogravure is a time-consuming, labor-intensive, costly process used today by fine-art photographer-printmakers.
References and quotes: http://www.photogravure.com/about/index.html
