In Terms of Media: Printing


This article originally appeared in Issue# 9

Printing has a language all its own. A knowledge of its vocabulary will help you understand the process and improve your working relationship with the printer.

The best way to bring your project to the printer is in the form of camera-ready copy. Camera-ready copy is any material to be photographed by the printer for reproduction without further changes. It is also called a mechanical. It is quite important to write all your instructions related to the mechanical either in the margins of the camera-ready art or on an overlay tissue over the art work in addition to discussing them with the printer. Take nothing for granted.

The printing process begins when your work goes to the process camera... sometimes called a copy camera or graphic arts camera. The camera is a large, sturdy machine especially designed for copying camera-ready art, making halftones and color separations. Line copy and continuous tone copy are photographed separately because each requires a different technique. Line copy consists of solid lines or areas that have no gradation of tone. Examples of line copy include typesetting, pen and ink drawings and typewritten sheets. A line shot is used to photograph line copy.

Copy that contains a range of grays or colors -- wash drawings or photographs -- are examples of continuous tone copy. To reproduce continuous tones, it is necessary to re-photograph them with a halftone screen which reduces the photo or art work to many tiny dots which vary in size, shape and spacing in order to reproduce the various shades from white to gray to black.

Line conversion screens are used to create a wide range of special effects (e.g. wood grain, cross hatch, linen weave, etc.) and tint screens are used to withhold a percentage of color.

The copy board, located on one end of the camera, contains the material to be copied. The technician can move the copy board close to the lens or away from it resulting in an enlargement, a reduction or an exact-size copy. Film and screens, if required, are placed behind the lens in a compartment on the opposite side of the camera. When all materials are in place the technician sets controls for correct exposure and activates the camera. The film is then developed in chemical solutions and hung to dry.

Negatives are taped in position on a sheet of colored plastic or paper called goldenrod. This assembly of negatives in position is called a flat. Then several pieces of work are to be exposed together to make one plate, care is taken that each flat is lined up or registered. Register holes fit accurately onto register pins on the table where negatives are stripped into the flat. A technician checks all negatives carefully for dust spots, size, register and art marks, position and layout. A blueprint or brown-print (sometimes called a blue-line or brown line) is a contact photo print made on paper from the negatives. It is used as a proof to check the position of all the work before the printing plate is made. This is your final opportunity to correct any mistakes. After mistakes are marked on this copy, the technician makes final corrections on the copy.

The last step is to make the printing plate from the corrected negative. The plate may be either metal or paper coated with a light sensitive chemical similar to that used on photographic paper. The printer puts the flat in a vacuum frame and the plate is exposed to ultraviolet light. After exposure the plate is chemically treated so that later on, when the plate is on the press, the image area will reject the water solution and accept ink; any non-image area will accept water and reject ink.

After the plate is attached to the press, paper is stacked in position and the press is set in motion. The finished piece is folded and may be bound in one of several methods: stitching (which is really stapling), gluing, or sewing. A trimming machine then cuts the piece to its exact size.