Printing Technology | Research & Encyclopedia Articles

Printing Technology

If we define printing as the process of transferring repeatable designs onto a surface, then the first known printing was done by the Mesopotamians, who as early as 3000 b.c. used stamps to impress designs onto wet clay. Printing on paper developed much later; Chinese inventor Ts'ai Lun (50?-118? a.d.) produced the first paper in 105 a.d. Chinese books printed with inked wood blocks survive from the T'ang Dynasty (618 a.d.-907 a.d.), and it was the Chinese--not German printer Johannes Gutenberg, as is widely believed--who developed movable type, allowing printers to compose a master page from permanent, raised characters. Pi Sheng invented movable type around 1045; he fashioned his characters of heat-fired clay. Later printers improved on his design by using characters made from lead. However, movable-type printing did not achieve the popularity in medieval China that it later would in Europe; as the Chinese language has some 80,000 characters, their printers ultimately found it more convenient to use carved blocks.

Thus Johannes Gutenberg, who built his first printing press around 1440-1450, could be said to be the first inventor of a lasting system of movable-type printing. Printing technology had only a brief existence in Europe before Gutenberg. The Mongol invasions of the fourteenth century introduced wood-block printing to Europeans, who had relied on copyists, particularly monks, to produce laborious, handwritten manuscripts. The design of Gutenberg's press, which employed metal characters, was based on machines used to press cheese and grapes. The set type, or matrix, was placed in a sliding track, moistened by ink-coated leather balls, and pressed to paper by a plate, or platen, which was moved by hand. The printing of Gutenberg's famous Bible in 1455-56 prefigured an explosion in European printing. The crude machine (it could print only 300 sheets per day) was nonetheless enormously faster than hand copying; the improvement was so staggering that many believed it the work of Satan.

Before the printing press, books were luxuries even among the educated; a small shelf of books was the hallmark of wealth. By 1500, several million books had been printed throughout Europe. Mechanical printing swelled the readership and variety of printed material, making possible magazines, newspapers, and the rise of the novel as a literary form. Yet, almost four hundred years later, printers were still using essentially the same machine as Gutenberg's--setting type, inserting paper, and pressing the platen all by hand (a few innovators refined the machine's design, replacing the original wood with stone or metal). Printing shops had difficulty in meeting the public demand for print products.

Finally, in 1811, German inventor Friedrich König discovered a way to harness steam power to drive a press in which the flat platen was replaced by a revolving cylinder; his machine could print over a thousand pages an hour. The constant motion offered by a cylinder is far faster and more efficient than moving a flat surface in a vertical or horizontal plane, and for this reason American inventor Richard M. Hoe invented a press in 1846 that also used a cylinder to carry the type. An 1857 version of Hoe's rotary press could print 20,000 individual sheets an hour. In 1865, William Bullock developed the first web press in 1865, in which rolls of paper replaced single sheets, further speeding the process. Indeed, the Although printing presses were now capable of producing material in large volumes and at high speeds, printing technology was still constrained by the typesetting process.

Typesetters still employed the method of setting pre-cast letters by hand, or by operating machines that were a little more efficient. In 1886, German-born Ottmar Mergenthaler invented the linotype machine, which operated on an entirely different principle. An operator typing at the linotype keyboard moved letter forms into place; the machine automatically spaced the line, then poured over it a metal alloy, which cooled into a full "line of type." Its speed was a great benefit to newspapers, which often need to be reset as news breaks. Linotype and its rival, monotype, introduced in 1897 by American inventor Tolbert Lanston (1844-1913), dominated typesetting until the mid-twentieth century.

The rise of photography in the late 19th century allowed printers to apply methods used for reproducing art--such as lithography and engraving--to text, and it eventually allowed them to make text matrices almost instantaneously. In each of these processes, including photoengraving and photolithography, the object to be reproduced--whether a piece of art or a sheet of type--is photographed. Light is then shone through the clear parts of the negative (those which would show up dark in print) onto a plate coated with a light-sensitive gel. The exposed areas of gel harden and the rest is washed away, resulting in a reproduction; the plate can then be inked (with an ink that adheres only to the gel) or etched (with an acid that eats only the exposed portions), and the thin plate is affixed to a cylinder on the printing press. Printers were enabled to reproduce finely-shaded material, like photographs, through the halftone process invented by Frederic Eugene Ives.

The major printing innovations of the late twentieth century center around electronic methods of typesetting. Printing in the early twentieth century involved an awkward marriage of modern and old-fashioned technology, in which entire metal plates of text had to be produced simply to be photographed and then destroyed. Photocomposition, or phototypesetting, developed after World War II, is the process of printing text directly on film (bypassing the hot-metal typesetting stage), using "master" characters stored on film or in computer memory. Just as nineteenth-century printing innovations made use of technology, phototypesetters employed computer technology; text is input not by a single operator, but is fed in by tape or computer disk, so that any number of typists can key in parts of the same text. These phototypesetting systems can set type at speeds of tens of millions of characters per hour, uninhibited by the physical limits of their operators, and massive works, such as encyclopedias and indices, can be stored on disk and revised without being completely retyped.

In the 1990s, the film step was being replaced by computer to plate printing technology (known as CTP), usually a digital process. Instead of converting files to film, plates are made directly from computer files. There are computer programs, such as PROSE (production order specification/EDD), which facilitate CTP. It is predicted that the printing process will soon become all digital, and film will disappear entirely. All Another innovation is waterless printing, which involves different kinds of plates. Instead of metal, usually aluminum, plates are made of silicon or plastic. Parts of these plates are not affected by ink, so there is no need for water. (Water was used to protect non-imaging parts of the plate from ink.) Computer technology will also effect binding equipment, so advertising and articles can vary to target specific customers.

A common problem found with newspapers since the inception of the press was ink that smudged, leaving a residue on the reader's hands. In the 1980s and 1990s, low-smudge inks were developed to combat this problem. The low-quality ink used on newspapers smudged because it was made from carbon black and mineral oils, which never fully dry on paper. There are several kinds of low-smudge ink, made with water instead of oil bases, or with agents that force the ink to fully dry. Other, less expensive, low-smudge options include ink that dyes the paper, invented by Rodger Gamblin of Dayton Tinker Corp. in Ohio.

Today, electronic miniaturization, and "pressureless" printing methods (those used by photocopying machines and laser printers) allow many individuals to produce printer-quality documents at home.