Technological factors

See also: History of Western typography and Medieval technology

At the same time, a number of medieval products and technological processes had reached a level of maturity which allowed their potential use for printing purposes. Gutenberg took up these far-flung strands, combined them into one complete and functioning system, and perfected the printing process through all its stages by adding a number of inventions and innovations of his own:

Early modern wine press. Such screw presses were applied in Europe to a wide range of uses and provided Gutenberg with the model for his printing press.

The screw press which allowed direct pressure to be applied on flat-plane was already of great antiquity in Gutenberg's time and was used for a wide range of tasks.^[13] Introduced in the 1st century AD by the Romans, it was commonly employed in agricultural production for pressing wine grapes and (olive) oil seeds, both of which formed an integral part of the mediterranean and medieval diet.^[14] The device was also used from very early on in urban contexts as a cloth press for printing patterns.^[15] Gutenberg may have also been inspired by the paper presses which had spread through the German lands since the late 14th century and which worked on the same mechanical principles.^[16]
Gutenberg adopted the basic design, thereby mechanizing the printing process.^[17] Printing, however, put a demand on the machine quite different from pressing. Gutenberg adapted the construction so that the pressing power exerted by the platen on the paper was now applied both evenly and with the required sudden elasticity. To speed up the printing process, he introduced a movable undertable with a plane surface on which the sheets could be swiftly changed.^[18]

Movable type sorted in a letter case and loaded in a composing stick on top

The concept of movable type was not entirely new in the 15th century; sporadic evidence that the typographical principle, the idea of creating a text by reusing individual characters, was well understood and employed in pre-Gutenberg Europe had been cropping up since the 12th century and possibly before. The known examples range from Germany (Prüfening inscription) to England (letter tiles) to Italy.^[19] However, the various techniques employed (imprinting, punching and assembling individual letters) did not have the refinement and efficiency needed to become widely accepted.
Gutenberg greatly improved the process by treating typesetting and printing as two separate work steps. A goldsmith by profession, he created his type pieces from a lead-based alloy which suited printing purposes so well that it is still used today.^[20] The mass production of metal letters was achieved by his key invention of a special hand mould, the matrix.^[21] The Latin alphabet proved to be an enormous advantage in the process because, in contrast to logographic writing systems, it allowed the type-setter to represent any text with a theoretical minimum of only around two dozen different letters.^[22]
Another factor conducive to printing arose from the book existing in the format of the codex, which had originated in the Roman period.^[23] Considered the most important advance in the history of the book prior to printing itself, the codex had completely replaced the ancient scroll at the onset of the Middle Ages (500 AD).^[24] The codex holds considerable practical advantages over the scroll format; it is more convenient to read (by turning pages), is more compact, less costly, and, in particular, unlike the scroll, both recto and verso could be used for writing − and printing.^[25]

A paper codex of the acclaimed 42-line Bible, Gutenberg's major work

A fourth development was the early success of medieval papermakers at mechanizing paper manufacture. The introduction of water-powered paper mills, the first certain evidence of which dates to 1282,^[26] allowed for a massive expansion of production and replaced the laborious handcraft characteristic of both Chinese^[27] and Muslim papermaking.^[28] Papermaking centres began to multiply in the late 13th century in Italy, reducing the price of paper to one sixth of parchment and then falling further; papermaking centers reached Germany a century later.^[29]
Despite this it appears that the final breakthrough of paper depended just as much on the rapid spread of movable-type printing.^[30] It is notable that codices of parchment, which in terms of quality is superior to any other writing material,^[31] still had a substantial share in Gutenberg's edition of the 42-line Bible.^[32] After much experimentation, Gutenberg managed to overcome the difficulties which traditional water-based inks caused by soaking the paper, and found the formula for an oil-based ink suitable for high-quality printing with metal type.^[33]