Landmarks in printing; from movable type to the microchip

UNESCO Courier, July, 1988 by Werner Merkli

A key invention in modern gravure printing was a photographic etching process using carbon tissue, developed by the Czech painter and graphic artist, Karl Klic, or Klietsch, in 1878. Since then, millions of illustrated publications have been produced by gravure printing (13).

In 1908, two Germans with experience in cotton printing, Ernst Rolffs and Eduard Mertens, developed a flexible steel "doctor blade" to wipe excess ink from the printing plate. Later, the process of etching the printing cylinder was greatly improved by the introduction of automated, electronic engraving.

Lithography and offset | The lithographic technique was discovered by chance in 1796, when the Munich dramatist Aloys Senefelder, searching for a economical method of printing his own work, tried writing on a finely-ground stone surface and discovered the water-repellent properties of his greasy, oil-based ink.

Initially, the images to be reproduced were hand-drawn on a litho stone (14) and printed on a manual press (15). The impression was taken by pressing the paper against the inked stone with a scraper. Thanks to the mechanization of this technique with Georg Sigl's flat-bed litho press, introduced in Berlin in 1851, single and multi-colour lithographic printing (16) became very important, especially for printing packaging material.

As early as 1805 Senefelder had tried to find an alternative to the heavy litho stone, but it was not until 1904 that Ira W. Rubel and Caspar Hermann of New Jersey, USA, devised a thin metal plate to carry the image to be printed. After this had been inked, and the surplus ink repelled with moisture, the image was transferred to a rubber-coated cylinder and then to the paper (17). This form of indirect printing is known as offset. The fact that the printing plate, the rubber blanket and paper all ran on cylinders enabled higher printing speeds to be achieved from the start.

In the early offset litho presses, the need for dampening often caused serious problems and the impressions obtained were dull and blurred. After the Second World War, technical improvements combined with better inks and more thickly-coated paper, resulted in sharper impressions and higher ink saturation.

Today, large electronically-controlled offset rotary presses, with several printing units in sequence, can print both sides of the paper, in sheets or as a continuous web, at the rate of 30,000 impressions per hour (18).

Revolutions in typesetting | In the nineteenth century attempts were made to mechanize text composition, which was still carried out line by line with individual metal characters assembled in a composing stick (19), following a process that had not changed greatly since Gutenberg's time. The first patent for a typesetting machine was taken out in 1822 by William Church of Boston; others soon followed (20).

But the real breakthrough in the mechanical setting and casting of type was achieved in 1884 by the German-born watchmaker Ottmar Mergenthaler in Cincinnati, USA, when he invented the Linotype machine, which could set 6,000 characters per hour as compared with 1,400 by hand. In the Linotype system (21), the brass matrices in which the characters are engraved in negative form are released from the storage magazine by typing on a keyboard, assembled into a line and moved into the casting mechanism. After casting, the entire lead line or "slug" is ejected and the matrices carried back to their position in the storage magazine where they remain on call for another line.