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The Heidelberg website glossary explains, in alphabetical order, a multitude of terms relevant to printing, as well as some terms used in Heidelberg's product catalogue.

Simply click on the letter of your choice to access the information you need.

Laminating
The general process of covering or coating one type of material with another, creating a bond between the two materials. In the postpress stage, laminating is one of the methods used to give the product protection or a more attractive appearance. To do this, films containing photographic or other print motifs are applied under pressure to the material being finished. If a transparent polyester film is applied, this is known as film laminating. Laminated materials are often found on drinks and food menus. For packaging liquids, the industry generally uses films that also protect the product’s aroma.
LAN (local area network)
A computer network that usually spans an area of no more than 10 kilometers.
Laser diode (injection laser, diode laser)
A point light source or light emission aperture driven by laser beams.
Laser imagesetter
Output device in which a light beam emitted by a laser light source is directed onto a photo-sensitive material via optics and/or mirrors. Single dots (spots) are produced by means of upstream on/off switches that are synchronized with the deflecting unit, the correlation of the spots is driven by a software program or a page description language as well as the laser imagesetter’s driver.
Laser printer
A standard printer with a rotating drum, the surface of which conducts electricity when it comes into contact with light. The surface of the drum is first electrically charged, a beam of laser light then records the printing information on the drum line by line by means of a rotating mirror wheel. When light comes into contact with the surface of the drum, it is discharged. The toner which is then applied only adheres to the places that are not illuminated. When transferred onto the paper and fixed in place using heat, the toner produces the print image required.
LCD (liquid crystal display)
Technology employed in flat screen displays, in which liquid crystals are used in the individual pixels of the monitor. See “TFT”.
LDAP (lightweight directory access protocol)
A protocol for the querying of address directories on the Internet.
Leading (line spacing)
The space between the lines of characters, measured in millimeters or DTP points.
Leporello fold
See "concertina fold".
Letter fold (business letter fold, brochure fold, spiral fold, barrel fold)
Folding pattern in which the folds are parallel and in the same direction, so that a kind of spiral is produced. The letter fold is a parallel fold. Two or more panels of the same width of the folded signature are folded around one panel. When the signature is folded twice, there are three panels on each side (six pages); with a tri-fold, the result is four panels on each side (eight pages). Back to top


Letter spacing
See "spacing".
Letterset
The term for indirect letterpress printing, in which the ink is transferred from the printing form onto the printing stock via a blanket cylinder without dampening. It is also erroneously referred to as dry offset, which causes confusion with waterless offset printing. Applications of the letterset process include continuous forms and package printing.
Letterpress printing
Printing process in which the elevated sections of a printing form are inked up and deposit some of the ink on the material to be printed. There are three forms of letterpress printing – in platen printing one surface presses against another; a cylinder press involves a cylinder pressing against a surface; and in rotary printing two cylinders roll against one another. Letterpress printing, the oldest industrial printing process, is used in sheetfed printing for small print runs and special assignments (punching, stamping, perforating, numbering, etc.) and for newspaper printing, though this is now becoming less common. Letterpress printing, in the form of flexographic printing, has been able to hold its own against offset and gravure printing in the area of package printing.
Ligature
Identical letters written together, such as “ff” or “tt”, or letter combinations such as “fl” or “ft” that are treated as a single letter.
Light gathering
See "dot gain".
Light-fastness
Refers to the resistance of inks to the spectrum of natural light. According to the German standard DI 54003/4, the “wool scale” defines eight levels from “very low” to “excellent”. Level three – moderately light-fast – indicates that the ink can be exposed to sunlight for 4 to 8 days in summer and 2 to 4 weeks in winter without any noticeable fading. At the highest level of light-fastness, the ink can withstand exposure to summer sun for more than 18 months.
Line engraving
Refers to a printing plate (generally for letterpress printing) which is created by etching on the basis of a line original.
Line original
Single or multi-colored original in which each color is present in a single tonal value. Generally speaking, line originals are used for black/white illustrations, such as drawings.
Line spacing
See "leading".
Link
In hypertext systems, especially on the World Wide Web, a listing of another internet page. Text segments, or also images and other graphic elements, can be linked. In texts, links are generally indicated by a special type format. Otherwise, a link can be recognized by the fact that the cursor changes (usually into a pointing hand) when positioned over it. In modern word processing programs, it is also possible to define links that refer to other, locally available files or Internet sites. Back to top


Linotype
The machine patented by Ottmar Mergenthaler in 1882, which was the first fully functional line composing machine and revolutionized the entire printing industry, in particular newspaper production. Used for the first time by the New York Tribune newspaper in 1886, the Linotype remained basically unchanged in its basic functions – despite numerous improvements – until it was replaced by electronic typesetting procedures. Using a keyboard similar to a typewriter, it assembles the metal matrices of letters and other characters and the interlaying spaces to form lines of print which are automatically cast using a lead alloy. Lines of print created in this way can then be compiled into text columns. One of the Linotype’s major innovations was the fact that the matrices could be reused, the machine automatically sorting and assigning these to their stock positions using a mechanical coding system.
Linux
Open source operating system based on UNIX System V and BSD UNIX.
Lithography
Invented by Alois Senefelder in 1789, a method for producing printing forms for stone printing. Using special ink or chalk, the printing copy is transferred directly onto a smooth-ground block of carbonate of lime (calcium carbonate – CaCO3). The stone block is moistened before being inked up with oil-based printing ink. The printing areas then take up the oil-based ink, while the unchanged limestone repels it. The word lithographs (“lithos” for short) is also used colloquially for copy for offset printing (screened images, line engravings).
Lithographic printing
Refers to all printing processes in which the printing areas of the printing plate lie on the same or virtually the same plane as the non-printing parts. This technology takes advantage of the fact that it is possible to create both oleophilic (oil-friendly) and hydrophilic (water-friendly) areas on the printing surface. When the plate is inked, only the oleophilic areas retain the ink. The first lithographic process was stone printing, invented by Aloys Senefelder in 1796. Offset printing is based on this technology.
Long grain
See "grain long, grain short".
Logging
Recording of computer activity used for statistical purposes as well as for backup and recovery. Log files are created for such purposes as storing incoming text dialog, error and status messages and transaction details.
Lumbeck system
Polyvinyl acetate adhesive binding system used for brochures, books and other printing materials, in which the ends of a pile of sheets are fanned out. After clamping, the leaves are fanned out in one direction and coated with glue. This process is then repeated on the other side. The process is named after the bookbinder Emil Lumbeck (1886-1979).
Lumen
One lumen is the amount of light emitted by a light source with a luminous intensity of one candela (cd) into the spheridian unit of one steradian (sr – quotient of the superficial content of a segment of a spherical surface and the square of the associated radius of the sphere). The lumen unit is now mainly used in a form defined by the American National Standards Institute (called the “ANSI lumen”). To this end, the average of the brightness values measured at nine points on an illuminated surface is taken and the luminous flux determined on the basis of a table published by the Institute.
LWC
See "HWC". Back to top


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