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Printing Glossary

This glossary of printing terms was created by people working in today's printing industry and is brought to you by MirPrint.com. It has been revised and edited and we have rewritten some technical descriptions in every day language to help the non technical person. Any suggestions that you may have on how we can improve this glossary will be carefully considered. Please send your comments and any new definitions to us at MirPrint.com.

Gang

The term Gang can refer to grouping images, photographs, or other original art together for shooting negative or color separations, rather than making each exposure separately. It can also mean the running of two or more printing jobs simultaneously.

Gate Fold

In a Gate Fold the left and right edges of the paper fold inward with parallel folds and meet in the middle of the page without overlapping. The paper might be folded again down the middle so that the folded edges meet and a fold is created in center panel of the paper.

Ghost Halftone

A Ghost Halftone is an image comprised of a series of very small dots whose density has been reduced to produce a very faint image.

Ghosting

Ghosting is an offset printing defect characterized by the appearance of faint replicas of printed images in undesirable places, produced in one of two ways. Mechanical ghosting is characterized by the appearance of a "phantom" image on the printed side of the sheet; it appears during printing and is easily detectable in the delivery tray. It can be caused by such things as ink starvation, as heavily-inked areas on the plate aren't always adequately re-inked by the form roller, or by incorrect-diameter form rollers. Chemical ghosting, also called gloss ghosting or fuming ghosting, is characterized by a "phantom" image on the reverse side of a sheet originating from the sheet below it (not caused by ink setoff), and typically results from an ink reacting with and altering the drying of the ink on the sheet on top of it. Ghosting can also refer to a faint reproduction of an image without actual ink transfer.

Gloss

Gloss refers to the quality of a paper that causes it to appear shiny. When light hits a paper's surface, the orientation of the reflected light rays (or specular reflectance) determines a paper's gloss. A paper that has undergone extensive calendering, supercalendering, or coating, or has had its surface highly polished, will reflect the light primarily as parallel rays, or all in the same direction. This is what causes a paper surface to be shiny, or "glossy". Glossy papers are used in some printing jobs to increase the gloss or color brilliance of the printing ink (glossy paper reflects light back through the ink), and less glossy papers are used in other printing jobs to reduce eyestrain (the high degree of reflected light makes text printed on glossy paper hard to read).

Gloss Ink

Gloss Ink is a variety of printing ink produced with an additional quantity of varnish that allows the ink to dry with a highly glossy finish, typically by oxidation and polymerization. High gloss inks achieve their best results when used on paper (typically coated paper) that allows a high degree of ink holdout, or does not allow rapid penetration of the ink vehicle into the paper surface. Rapid drainage of the fluid vehicle hampers oxidation and reduces printed gloss. The application of heat to expedite ink drying also works to reduce printed gloss. High-gloss inks are manufactured for use in both letterpress and offset lithographic printing processes.

Grade

Grade is a method of categorizing different types of paper by size, weight, pulp composition, manufacturing procedure, thickness, and end use. There are hundreds of different paper grades and sub-grades.

Gray Balance

Grey Balance refers to combinations of cyan, magenta, and yellow inks which produce neutral shades of gray. Improper proportions of any of these colorants will result in one particular dominant hue, which may or may not be desirable. Regardless, it is necessary to ensure a consistency of the gray balance throughout the proofing and printing processes.

Gray Scale

A Grey Scale is a thin strip of paper or film containing 15:20 shades of gray, increasing in density (typically in a logarithmic, not linear, fashion) from white to black, used to analyze and optimize the contrast of color and black-and-white images. Gray scales come in a variety of different forms, for different types of reproduction. A gray scale can be supplied on film, as either continuous tones or halftone dots. If it is on film and comprises discrete stages of gray, it is called a step tablet. If it is on film and comprises a single continuous strip of progressively dense gray, it is called a continuous wedge. If it is on film and comprises halftone dots in discrete levels of gray, it is called a halftone scale. Gray scales are often printed beyond the trim boundaries of printed pages as a means of ensuring the consistency of the print characteristics. On a computer monitor, gray scales are produced by varying the intensity of the pixels, on a scale of white to black. Images saved in the TIFF file format convert gray scale information into printer commands, which instruct the printer to construct a bit map plotting all the levels of gray for each spot in the output. The more levels of gray that a computer and printer can discern, the smoother and more realistic the image.

Grind Edge

Grind Edge is an alternative term for the The edge of a printed sheet or paper web on which binding is to occur.

Gripper Edge

Gripper Edge means the edge of a sheet of paper passing through a sheet-fed press containing the gripper margin, or, in other words, that edge of the sheet which is grasped by the grippers of the press. The term gripper edge also refers to the edge of a wraparound printing plate which is secured by the plate clamp.