This project is designed for both skilled and unskilled concerned with modern printing standard, whether as a student, private practitioners, commercial publishers or as an author. It explains the art of printing technology as a basic human faculty which shape all human artifacts, of modify the physical, social, academic, spiritual and emotional world.
To learn and practice modern printing processes properly, we need to perceive its scope, depth and not to think of it only in terms of producing words and pictures on any selected substrate with the aim of passing information or decoration so, this project takes account of history of printing, mode of selecting a printing process specialized for a particular job or production which depends on the factors to be treated a head and besides, the project considers modern printing processes and invention of these multi – purpose and complex machine as one manifestation of that broad human faculty.
A modern printer works to give solution to these four major necessities.
In conclusion, by means of resolving these basic problems, a printer will acquire and also improve on craft, industrial skills, mental modeling which envisages problem as well as enhancing great ideal production.
PREFACE
The invention of printing in the middle of this century represents one of the great landmarks in human history. A product of the rebirth of culture and society known as the Renaissance, printing made possible the wide dissemination of knowledge, the rapid flow of ideas from one country to another, and the popularization of learning.
This discovery is credited to Johann Crutenbery a German printer, but actually his great contribution lay in assembling all the elements, that make up printing and that had been known, at least in the far east, for centuries.
Generally, printing is the art and technology of reproducing words and pictures on paper, cloth or other surfaces. Although, there is considerable variation in printing plate or similar image – bearing surface to the material being printed; most all printing is done by one of five major printing methods – letterpress, offset lithography, Gravure, screen printing or collotype process.
A series of inventions in the 19th century, spurred by the technological advances in all fields that marked the industrial revolution, brought about sweeping changes in the art of printing. Most of these involved radical improvements in presses, new method of paper manufacturers, plate making, phototypesetters, computers for automatic justification, electronic, scanning machines for use in colour printing and electrostatic screen printing.
The choice of using a particular process in printing may be summarized into two influential points.
Lithography is the dominant printing processes but its growth is being challenged by Gravure.
Letterpress is also expected to continue to decrease in use, as flexography replaces letterpress and even lithography in the newspaper field, and will also be used in other publishing areas such as newspaper inserts and low budget machines.
Screen and other related processes are also expected to grow as inkjet and electronic printing increase in use, as well as reprography, which is the basic of quick and in-plant. Electronic and inkjet printing will continue to pose threats so traditional printing’s markets.
TABLE OF CONTENTS
CHAPTER ONE:
LETTER PRESS PRINTING
CHAPTER TWO:
OFFSET LITHOGRAPHY
CHAPTER THREE:
GRAVURE
CHAPTER FOUR:
SCREEN PROCESS PRINTING
CHAPTER FIVE:
OTHER PRINTING PROCESSES
Bibliography
CHAPTER ONE
LETTER PRESS PRINTING
Letterpress is a highly versatile printing process. It is adaptable to both short and long printing runs, from a few hundreds to several millions of printed impressions. In letterpress printing the image area of the printing surface stands in relief, raised above the surrounding non-image areas. Ink is applied to the image areas with a roller and is transferred to paper under pressure. Letterpress printing process is derived from pre-industrial art of woodcut.
Some letterpress printing is done directly from handset or machine – cast type. The type is positioned as it should appear on the printed sheet within a steel frame called a chase. It is held in position by wood blocks called furniture & locked up tightly by means of wedge – shaped devices called quoins. The resulting assembly of type, called a type former or from is placed on the printing press and linked, and impressions are made.
Printing from type is used chiefly for stationery, business cards, circulars, and similar small jobs where only a small quantity is to be printed. It is not feasible for longer printing runs of many thousands of copy because type metal is relatively soft and wears down quickly, while it is on press. In addition, if the type is damaged the entire composition process has to be repeated.
The shortest printing runs the letterpress type form is replaced by a printing plate. The starting point of the plate making process is a negative of the image on film, line art, or continuous tone originals that have been made into halftone negatives.
The most widely used processes for making original letterpress plate involve three steps:-
Photopolymer plastics are also used for letterpress plates. These light sensitive plastics harden on exposure to light. The plastic plate is exposed by shining aultraviolet light through a negative in contact with the plate. Where the light strikes the plastics, the surface becomes hard and insoluble. The portion of the surface not exposed to light remains soluble and can be washed away, leaving the printing image raised the non-image background.
They are made from type and from original engravings of illustrations. Duplicate plates can be made quickly and inexpensively from original often several sets of duplicate plates are made to permit printing on several presses at the same time. The curved plated needed for rotary presses are made as duplicate plates from flat originals.
Duplicate plates are usually stereotypes.
Electrotypes or rubber plates.
1.4 LETTERPRESS PRINTING PRESSES
There are three major types of letterpress printing presses namely:-
All are based on the principle of inking the raised image on the former or plate and printing a sheet of paper against the inked image. The processes differ in the way in which the former or plate is carried in the press, and in the way in which paper is brought the paper is brought into contact.
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