Printing with wooden formes on paper was something Europe had been familiar with since the late 14th century. Gutenberg’s concept went one important step further than this simple form of printing; his basic notion was that any text could be reduced to its individual components, to its letters, numbers and punctuation marks. He was concerned with finding a process which would enable these elements to be mass-produced, the texts they composed to be printed to faultless perfection and the elements themselves to be reusable, which in turn would save not only materials but also space.
Punches and Matrices
If you imagine just how many stages of planning and experimentation were needed until this pioneering invention produced results which were faultless in every respect, then it is quite plausible that several years passed until all details had been perfected. The various steps Gutenberg had to take to turn his ideas into practice included producing –
with absolute precision – the individual letters and characters of what printing jargon calls “figures” as punching dies. These dies, uniform in size and style, were engraved in a hard metal (probably steel) and could be vertically “punched” into a softer metal when and as often as required. This produced a negative or a matrix, made of a square of copper or any other soft metal.
The Hand Mould
The hand mould or casting instrument was developed to cope with mass production. The caster was a hollow mould or cast made out of metal with wooden clamps which could be separated into two and placed in the matrix. This saved vast numbers of hollow moulds having to be produced.
The casting metal, an alloy of lead, tin and other admixtures, presumably antimony, was heated to almost 300°C and poured into the remaining opening in the manual caster. Letters could be removed immediately and only had to have the metal casting tip removed with a hammer. The letters were then placed in a type case and sorted according to the frequency with which they were used.
Setting and Printing
Before printing commenced the compositor made up one or more lines in a composing stick. These lines were then arranged in a galley (a wooden tray) to make up the printing forme for the page. The forme was then lifted into the wooden press.
The Printing Press
Screw presses used to make oil, wine and paper had existed before Gutenberg. In printing, a number of contraptions had to ensure that the plate exerting pressure, the platen, was pressed vertically onto the forme and was unable to twist out of position when the crossbeam or bar was moved sideways.
Unlike the watery ink used with woodcuts, printing ink had to be slightly sticky and a deep black to produce good-quality print. It was made from soot, oil and resin.
The inked plates were pressed onto evenly dampened paper – at least one double page at a time for books – and then hung up to dry on lines.