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Copy Preparation
Offset Copy Preparation, as a function in the Government Printing Office, serves as the inspector and judge for all reproducible materials used in lithographic production.
Offset Copy Preparation And Phototypesetting
To accomplish copy preparation efficiently, basic tools and equipment are necessary. The handwork tools are few and relatively inexpensive.
Preliminary Functions Of Copy Preparation
With the Copy Preparation Section serving as the clearinghouse for all offset materials, preliminary handling of new work becomes one of its most important functions.
Adapting And Assembling Of Materials
The copy preparer who receives the reproducibles as ordered in preliminary review continues the clearinghouse function.
Processing A Job Through Offset Copy Preparation
Because the operations are so diversified for this operation, a description of the tasks required for a specific job may present a more specific evaluation of this task.
Phototyepsetting
Phototypesetting is a method of photographically producing top-quality text and display typography on paper or film bases to be used in the preparation of camera copy for artwork.
Photography And Negatives
The purpose of the negative in lithographic production is to provide a suitable image which can be exposed on a plate to create a final positive printing image.
Photographic Materials
There are many kinds of film, and each type has its own particular purpose. Film of wide latitude and contrast for the production of line and top-quality halftone negatives is required for use in the Government Printing Office.
Line Photography
Line photography is the least difficult of the three general groups of products into which graphic-arts photography is divided.
Halftone Photography
The first practical halftone screen was in-vented by Max Levy, and is therefore often referred to as the Levy screen. The glass screen consists of two sheets of optical glass with fine parallel lines etched on one side.
Finishing
The finishing tasks receive all of this photographic material and arrange it into uniform complete page-size pieces ready for imposition.
Lithographic Platemaking
Lithographic platemaking provides an ink-receptive positive image and an ink-resistant (desensitized) nonimage area on a plane surface.
Graining
By means of chemical and mechanical action, graining provides a matte finish to a flat sheet of metal.
Deep Etch
Preparation and exposure of the plate is the same as for surface plates, although the length of exposure for deep etch is usually greater.
Diazo Coatings
The diazo coating can be applied to these aluminum plates in two ways. One method is to apply a pool of coating to the center of the plate and wipe this coating evenly over the plate with a suitable pad.
Bimetal Coatings
A bimetal plate usually has an image-forming copper layer plated onto a sheet of aluminum or steel. The processing of these plates removes the image-forming copper in the nonimage areas.
Lithographic Presswork
Lithographic presswork transfers a continuously inked image from a plane surface by means of a cylinder-mounted metal plate containing the image to a rubber blanket and then to a sheet or roll of paper.
Lithographic Printing
The lithographic press consists of many component parts. It is a precision machine which, during manufacture, requires very precise tolerance—in many instances less than 0.0005-inch variation.
Non Sheet Handling Components
The particular ink required for a job is placed in a trough or fountain which extends the full width of the press.
Offset Web Presswork
The principal advantage of offset over other types of printing production is the economy of preparatory operations.
Paper
Papermaking is an ancient craft. The Chinese are credited with a capability to produce a writing paper from mulberry fibers at the beginning of the Christian era.
Ink
A precise time and place origin of printing ink is unknown. The beginning of modern printing inks can be considered to be writing ink, which was used by the Chinese and the Egyptians as early as 2600 B.C.
Pigments
Pigments are the solid coloring matter in inks such as black, white, or any of the common colors. It is generally only the pigment which we see when examining printed matter.
Lithographic Troubles
Greasing or scumming. This condition occurs when the nonprinting area begins printing to a greater or lesser degree.
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