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Paper & Pulp Dictionary Glossary "G"

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 Definitions for commonly used terms, words and phrases used in the pulp and paper trade

 

 

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Gatefold
Two or more parallel folds on a sheet of paper with the end flaps folding inward.
Ghosting
Variation in ink gloss, density or color that are not part of the original design, but appear as a repeat or ghost image associated with another area of  the copy.
Glassine Paper
A translucent paper made from highly beaten chemical pulp and subsequently supercalendered.
Glazed Paper
Paper with high gloss or polish, applied to the surface either during the process of manufacture or after the paper is produced, by various methods such as friction glazing, calendering, plating or drying on a Yankee drier.
Gloss
The property that's responsible for a paper's shiny or lustrous appearance; also the measure of a sheet's surface reflectivity. Gloss is often associated with quality: higher quality coated papers exhibit higher gloss.
Gloss Mottle
Blotchiness or non-uniformity in the paper's gloss (unprinted or printed). Typically only visible at certain viewing angles. Usually attributable to poor formation and heavy calendering.
Grade
Papers are differentiated from each other by their grade. Different grades are distinguished from each other on the basis of their content, appearance, manufacturing history, and/or their end use.
Grain
The direction in which most fibers lie in a sheet of paper. As the pulp slurry moves forward on the papermaking machine's formation wires, the fibers tend to align themselves in the direction of movement. Binding books parallel to the grain allows for a smoother fold then working across the grain. Grain direction of sheet fed papers is usually indicated by underlining the number, e.g., 23" X -35". On a web press, the grain direction should run along the length of the paper web.
Grain Long
Grain running lengthwise along a sheet of paper.
Grain Short
Grain running widthwise along a sheet of paper.
Grammage
Weight in grams of one square meter of paper or board (g/m2); also basis weight.
Gravure
A printing process that uses intaglio, or recessed, image carriers. The image carrier, which is flat or cylindrical, moves through an ink pool. A blade scrapes excess ink off the plane of the plate, leaving ink in the recessed wells. A second cylinder presses the paper onto the plates, where it picks up ink from the wells. The high speed of gravure presses and the durability of the metal intaglio plates make gravure an economical printing method suitable for large print runs (more than two million copies).
Gravure Paper
Paper for gravure printing that has very low print roughness and good wettability of gravure inks.
Gray Board
A homogeneous board made usually of mixed waste papers with or without screenings and mechanical pulp on a continuous board machine, in thickness less then 1 mm.
Greaseproof Paper
A protective wrapping paper made from chemical wood pulps, which are highly hydrated in order that the resulting paper may be resistant to oil and grease.
Greenfield Mill
Mill or production facility built on undeveloped site.
Green House Gases
Gases that provide an insulating effect in the earth's atmosphere, potentially leading to global climate change. These gases include carbon dioxide, methane, nitrous oxide, ozone, and water vapor.
Green Liquor
The liquor that results when the inorganic smelt from the recovery furnace is dissolved in water is called "green" liquor.
Green Paper
Immature paper which has not been conditioned or had the opportunity to mature naturally.
Grinder
A machine in which logs are defibrated against a revolving grindstone.
Groundwood Papers
A general term applied to a variety of papers made with substantial proportions of mechanical wood pulp together with bleached or unbleached chemical wood pulps (generally sulfite), or a combination of these, and used mainly for printing and converting purposes.
Groundwood Pulps
A mechanically prepared (by grinding wood logs against a rough surfaced roll rotating at very high speed) coarse wood pulp used in newsprint and other low cost book grades where it contributes bulk, opacity, and compressibility. Groundwood pulp is economical since all the wood is used; however, it contains impurities that can cause discoloration and weakening of the paper.
Guar Gum
A natural polymer that is used as a dry-strength additive, often as a cationic derivative.
Guillotine
A machine used to trim stacks of paper, which works the same way the original French guillotine worked. A cutting blade moves between two upright guides and slices the paper uniformly as it moves downward.
Gurley Porosity
A method to measure the air permeability of paper by TAPPI method T536. See "Air permeability."
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