GLOSSARY OF PRINTING TERMS
Below please find an explanation of many printing terms to enable you to better understand the printing process.|
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A software program that automatically applies trapping to output from imagesetters or platesetters. Trapping is the precise relationship between two ink colors when they butt together on a printed sheet. If no trap is added, a white gap may appear between colors. If too much trap is added, a dark line will appear where the colors overlap.
The dimensions of a book or folded piece after it has been bound or folded into its finished state.
The acronym for the four basic ink colors used in four-color process printing: Cyan, Magenta, Yellow and Black.
COLOR SEPARATED LASERS
The process of printing a black and white laser for each color found in a document. I.E. a four-color process
document will result in four lasers when color separated: cyan, magenta, yellow, black.
Color separation is the breaking down of a full-color image into the four basic colors used in process-color
printing. Color originals are exposed to laser light scanning that, through the use of four color filters can “read”
and record the amounts of cyan, magenta, yellow and black that is present. The recorded data is converted into digital form and saved to a computer for further processing and placement into page layout programs.
DIGITAL COLOR PROOFS
Proofs created directly from digital art files-not film. Examples of digital proofs are toner-based black and white or color lasers, phaser wax proofs, dye sublimation, IRIS, thermal and ink-jet prints.
Originally the acronym for Desk Top Publishing-now it also stands for direct-to-plate in the platemaking process.
When a single photograph is printed using two ink colors it becomes a duotone. The most common two-color combinations for duotones are black plus a color. Duotones can also be created using two PMS ink colors.
The dimensions of a book or brochure before it is folded into its final bound size.
The tonal range from very light gray (1% dot) to solid black (100% dot) in increments of 1% ink coverage.
The reproduction of continuous-tone artwork, such as photography or pencil sketches, through a digital
screening process that converts shaded images into solid ink dots of various sizes and concentrations. A few,
tiny dots produces highlight areas. A heavy concentration of large dots produces mid-tone and shadow areas.
The planned arrangement of multiple pages or printed items on a single press sheet.
The acronym for Light Amplification by Stimulated Emission of Radiation. A laser is an intense beam with very
narrow band width that can produce images by electronic impulses from digital data.
Laser proofs are black and white or color digital proofs. They can be printed as composite or color-separated sheets. Composite laser proofs show all colors that will print on one sheet. Color-separated laser proofs show each ink color to be printed on its own separate sheet. I.E., a four-color process document will result in four
lasers when color separated: Cyan, Magenta, Yellow, Black.
The printing process based on the theory that water and oil will not mix. The lithographic printing process uses
a planographic plate to control where the printed image will appear. This plate is sensitized to be ink-receptive
in the image areas and water-receptive in the non-image areas. After the plate is placed on the printing press,
ink is applied to the surface of the plate and stays in the image-designated areas. A miniscule amount of a water
solution is applied to, and stays in, the non-image areas of the plate. This process of keeping the ink area
separated from the water area has an accuracy of 1/1000 of an inch.
The term offset is often used interchangeably with lithography. In fact, lithography is the whole printing process (based on the theory that oil and water don't mix). Offset is a step used within the lithographic process. When a printing plate transfers its inked image onto a rubber blanket before it transfers the same image onto paper, it is called an "offset" printed image.
Plates are the carriers of the images to be printed. One printing plate is required for each ink color printed.
Metal plates are used to produce high quality, close-register printed images. Lesser quality plates can also be made out of plastic and paper.
PMS INK COLORS
PMS is the acronym for Pantone Matching System and was developed by the Pantone Company for color
identification. The system assists clients, designers and printers to communicate about color. Each PMS color
has a unique number and formula for ink mixing. PMS colors are also referred to as "spot" colors.
The four basic ink colors used in process-color printing are cyan, magenta, yellow and black (CMYK). These
colors are semi-transparent inks that "process" with each other when overprinted in predetermined amounts. I.E., When cyan overprints yellow, it produces shades of green. When yellow overprints magenta, it produces shades of orange. Controlled screen tint combinations of the four basic ink colors allow the full spectrum of colors to be produced on a printing press.
PROCESS COLOR SEPARATIONS
Color separation is the breaking down of a full-color image into the four basic ink colors used in process-color printing. The making of a color separation involves the use of a laser light scanner which, through the use of four color filterings, can "read" and record the amounts of cyan, magenta, yellow and black that is present in any
particular area of a color original. The recording of this data is converted into digital form and saved to a computer for further processing and placement into page layout programs.
The quantification of output quality designated in dots per inch (dpi) when applied to paper output, and in lines per inch (lpi) when applied to film or plate output. Laser printers commonly hold resolutions from 300 to 1200 dpi. Film output units (imagesetters) use a resolution specified based on the surface type of papers to be printed. Newsprint can hold a resolution from 65 to 100 line screen. Uncoated papers typically use 133 to 150 line screens. Coated papers can hold resolutions of 175 to 200+ line screens.
SHEET-FED OFFSET PRINTING
Sheet-fed printing sends pre-cut sheets of paper through the printing press rather than paper fed from rolls.
Another name for PMS ink colors. PMS is the acronym for Pantone Matching System and was developed by the Pantone Company for color identification. The system assists clients, designers and printers to communicate about color. Each PMS color has a unique number and formula for ink mixing.
WEB OFFSET PRINTING
Web printing feeds paper through the printing press from a roll rather than using pre-cut sheets.