Actal qualities of photogravure

Photogravure registers a wide variety of tones, through the transfer of etching ink from an etched copperplate to individual 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 just 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 high standard in the late 19th century. The speed and convenience of silver-gelatin photography eventually displaced photogravure which fell into disuse after the Edward S. Curtis gravures in the 1920s. Many years later, photogravure has experienced a revival in the hand of Aperture and Jon Goodman, who studied it in Europe. Photogravure is now vigorously practiced in only several dozen workshops around the world. The document is viewed at a very shallow angle.

Techniques of intaglio printings

Intaglio is a printing technique in which the image is incised into a surface. Normally, copper or zinc plates are used, and the incisions are created by etching or drawing the image, but one may also use mezzotint. In printing, the surface is covered in ink, and then rubbed vigorously with tarlatan cloth or newspaper to remove the ink from the surface, leaving it in the incisions. A damp piece of paper is located on top, and the plate and paper are run through a printing press that, through pressure, transfers the ink to the paper.

The very sharp printing obtained from the intaglio process is very hard to imitate by other means. Intaglio also allows for the creation of latent images which are only visible when the document is viewed at a very shallow angle.

Gravure painting process

Rotogravure is a type of intaglio printing process, in that it involves engraving the image onto an image carrier. In gravure printing, the image is engraved onto a copper cylinder because, like offset and flexography, it uses a rotary printing press. The vast majority of gravure presses print on reel of paper, rather than sheets of paper. Rotary gravure presses are the fastest and widest presses in operation, printing everything from narrow labels to 12-feet-wide rolls of vinyl tiles. Additional operations can be in-line with a gravure press, such as saddle stitching facilities for magazine/brochure work.

The rotogravure process is still used for commercial printing of magazines, postcards, and corrugated (cardboard) product packaging.

In the latter quarter of the 19th century, the method of image photo transfer onto carbon tissue enclosed with light-sensitive gelatin was discovered and was the beginning of rotogravure.

Image plates in printing materials

Image plates are used to have the desired artwork "image" etched in its surface. Their function is to hold ink in this etched cavity, allows the pad to pick up this ink as a film in the shape of the artwork, which is then transferred to the substrate.

Two main types of printing plate materials: photopolymer and steel. Photopolymer plates are the trendiest, providing a good do-it-yourself option. These are naturally used in short to medium production runs. Steel plates come in two options: thin steel for medium to long runs, and thick steel for very long runs. Both steel plate types are commonly processed by the plate supplier as it involves the use of specialized equipment.

Main tactics for creating the printing plate

Two main techniques for creating a printing plate. The traditional techniques require a UV exposure unit and involve photo exposure with film positives and chemical etching of a photopolymer plate. A newer technique known as "computer to plate" needs a laser engraver and involves laser etching of a steel or specialized polymer plate. The later technique provides several advantages over the former; among them:

• Print quality is improved due to minimized loss of resolution. With photo exposure, the image is first transferred on film positive and only them, on the plate. Thus the image on the plate is second generation. With laser print, the image is transferred on the plate directly from a digital file. Thus the image is first generation and improved quality.

• The image on the plate is easily duplicated. Unlike chemical etching that involves several steps with many variables and manual work, laser etching is a simple, easily repeatable procedure with stable results. Plates can be made the same every time.