Letterpress is one of the oldest forms of printing. It involves printing text with movable type, in which the raised face of the type is inked and then pressed against a smooth substrate to achieve the desired image. The letterpress process is referred to as a “relief” process because the printed image is produced from a plate in which the image area is slightly raised above the non-image surface of the plate.
Since most letterpress equipment produces only one color at a time, printing with more than one color can be challenging. The inking system on letterpress equipment is less precise than on offset presses, which can create problems with some graphics. However, an experienced printer can overcome many of these problems.
Equipment Used in Letterpress Printing
There are three different types of letterpress printing devices in use today: Platen, Flat-Bed, and Rotary presses.
Rotary Letterpress Printing – There are two types of rotary letterpresses, sheet-fed and web-fed. On a rotary sheet fed press, the plate is mounted on a cylinder where a roller system applies ink to the raised area of the plate. The paper passes between the plate cylinder and an impression cylinder where the resulting squeeze between the two cylinders produces the printed impression on the paper. Web-fed rotary letterpress presses are used primarily for printing newspapers. These presses utilize a plate and impression cylinder, but instead of individual sheets passing between the two cylinders, the paper is a continuous web unwound from a large roll. Typically, they can print up to four pages across the web; however, some of the new presses can print up to six pages across a 90-inch web. Rotary letterpress is also used for long-run commercial, packaging, book, and magazine printing.
Platen-type Letterpress Printing – A platen press is made up of two flat surfaces called the bed and the platen. The platen provides a smooth backing for the substrate that is to be printed. The raised plate (image to be printed) is locked onto a flat surface. The plate is inked, the substrate is then placed on another flat surface called the bed and pressed against the inked plate producing the impression. Platen printing is typically used for short runs such as invitations, name cards, and stationary. Larger platen presses are used for die-cutting and embossing.
Flat-Bed Cylinder Letterpress Printing – Flat-bed cylinder presses use either vertical or horizontal beds. The plate is locked to a bed which passes over an inking roller and then against the substrate. The substrate passes around an impression cylinder on its way from the feed stack to the delivery stack. The presses can print either one or two-color impressions. Flat-bed cylinder presses operate very slowly, having a production rate of not more than 5,000 impressions per hour.
Letterpress printing has since been replaced by offset printing and other processes, but it is still used for some newspapers, books, and limited edition prints. Letterpress printing may also be used for producing small quantities of business cards, letterhead, and posters.