Category: Lithography

The principal advantage of offset over other types of printing production is the economy of preparatory operations. The use of paper prints and reproduction proofs instead of engravings and large metal forms affords substantial savings of preparatory time and materials in favor of lithography. There is another advantage in the lithographic process which until recently […]

Historical note.—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. One of the many skills which Marco Polo became familiar with in China was Chinese ability to produce handmade paper. It is believed that he brought back […]

To accomplish copy preparation efficiently, basic tools and equipment are necessary. The handwork tools are few and relatively inexpensive. Each copy preparer maintains a set of these basic tools for his personal use. Other equipment to be described will list those machines needed to complete the copy preparation workrooms. Preparers use a desk-size work surface. […]

MECHANISM 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. BROAD CLASSIFICATIONS OF TYPES OF PRESSES There are two general types of machines manufactured: (1) sheet-fed presses and (2) roll-fed presses. The distinction is simple. The sheet-fed press […]

1. THE INK SYSTEM The particular ink required for a job is placed in a trough or fountain which extends the full width of the press. An agitator moving continually across the fountain keeps the ink in a workable condition. Ink which is not worked continuously has a tendency to stiffen. In this condition good […]

INTRODUCTION 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. Many varieties and thicknesses of paper stock and numerous different colors of ink are needed and used to produce the […]

Recently an entirely new technique of platemaking has found wide acceptance in the industry. This process eliminates all of the graining and surface preparation procedures encountered with regular surface plates. The manufacturer supplies a sheet of aluminum which has been grained and treated at the factory ready to be coated and processed. The nature of […]

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. This gives an image in very slight relief which is exactly the opposite condition of a deep-etch plate which recesses the image base slightly below […]

Purpose.—By means of chemical and mechanical action, graining provides a matte finish to a flat sheet of metal. Actions of the abrasive with the driving force of the oscillating marbles provides an increased surface area Of 2 to 6 times the nominal dimensional area of the flat metal sheet. Graining also provides a capillarity which […]

Regular and copperized.—The regular method is applicable to both zinc and aluminum. The copperized plate is restricted to aluminum. The purpose of deep etch is to provide an image which is slightly below the general plane of the nonimage area. Although this depth is considered to be 0.0002 or 0.0003 of an inch deep, the […]