The letterpress has roots as old as seventh-century China, where wooden blocks were used to reproduce written characters on cloth. The letterpress in its "updated" form, tweaked by Johannes Gutenberg in the 15th century to have moving type sets, has been regarded as one of the single most important creations ushering in the modern era. It solidified language, allowed for mass media communication and began what is today a truly global information network.
Its invention caught the industrial revolution in Europe in stride, and with the advent of mechanization, the letterpress helped launch the newspaper into the dominant media form of the 19th to 20th centuries, with quick printing enabling daily runs of issues and large-scale distribution.
According to pneac.org, a leading organization in aiding printers and publishers, "Letterpress printing exerts variable amounts of pressure on the substrate dependent on the size and image elements in the printing. The amount of pressure per square inch or "squeeze" is greater on some highlight dots than it is on larger shadow dots. Expensive, time-consuming adjustments must be made throughout the press run to make sure the impression pressure is just right. Major chemicals used in letterpress printing, very similar to those used in lithography, include film developers and fixers, inks and blanket and roller washes. This process is how a letterpress produces an image on paper and shows how much care must be taken in its setup and maintenance.
There are primarily three types of letterpress printing machines: the rotary letterpress, the flatbed cylinder printing machine and the platen-type letterpress. Rotary letterpress machines are used because of their ability to efficiently produce material in high quantity. They're employed chiefly in commercial and specialty printing, such as newspaper and magazine production. This type of letterpress has two varieties: the sheet-fed rotary letterpress, which is declining in use and is no longer made in the United States, and the web-fed rotary. The web-fed rotary letterpress is used in the printing of newspapers; the sheet-fed has been used for more specialized projects, as its production speed is significantly lower than the web-fed rotary.
The flat-bed cylinder letterpress operates most slowly of all models represented. This type utilizes either a horizontal or vertical bed, which the plate is then locked into. The plate is the surface the presses' ink passes over, and it contains the document to be copied. The flat-bed has fallen out of favor with modern publishing companies, with much of their work now being printed on web-fed machines.
Platen-type letterpress machines are used for short-run projects such as place cards and stationery. This is the style of letterpress that sports the "clam-shell" like design that many may remember from small-town newspapers and independent literary journal publishers. The device is made up of two parts: the platen and the bed. Paper is placed on both the platen and the bed with the press opening and closing (like a clam shell) onto a flat surface where the type set and ink is located. These presses are usually quite old, with the majority having been built in the 1800s.