Duplication under pressure
Nearly everything that we interact with has, at some point or another, been through a printing press. I’ve used rubber stamps, and stencils, and I have a vague notion that any printing process is based on putting ink on some parts of the paper and keeping it away from others. I never really considered all of the complex methods of printing until I found a book on the subject and realized how interesting printing is.
There are several major methods for rapid large-scale printing. The original printing press and its decedents (rubber stamps) all use raised letters covered with ink to apply ink to only the desired portions of the page. Lithography or plate printing uses a plate that has been scored (scratched) and then covered with ink. The ink only sticks to the portions of the plate with the correct texture, and when the entire plate is brought into contact with the paper, only the scored areas leave ink on the page.
Intaglio printing (from the Italian word “carve”) is the second oldest form or printing. It predates lithography by roughly three hundred years. Intaglio printing uses a large plate like lithography, however, the Intaglio plate is carved to resemble what the artist wants printed. The ink is spread over the plate, and then wiped off, leaving the surface clean, and the ink in the wells. The paper is then applied to the plate under tremendous pressure to the paper, pushing the paper into the groves. A side effect of intaglio printing produces letters that are slightly raised off the paper from the front and slightly indented on the back. The most common variant of intaglio printing is called gravure and varies the depth of the recesses in the plate to vary the depth of the color (deeper wells mean darker colors.)
Intaglio printing costs many times more then traditional printing. An intaglio plate costs hundreds times more then an equal plate for offset printing. For traditional printing, intaglio is not a common choice, but intaglio has its advantages. Intaglio plates have an incredible life. Each plate can be pressed millions of time before it wears down, and intaglio plates produce levels of details that traditional offset printing plate’s can't. Because of their detail and expense almost all money is printed with an intaglio press. Every banknote, as well as all United States passports and high security documents are printed with intaglio presses.
While intaglio printing will never replace a LaserJets as a desktop printer or offset printers for printing books, intaglio presses will be around for as long as people need nothing short of perfection prints.