(G) Global Eco-labelling Network
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The Global Eco-labelling Network (GEN) is an association of worldwide eco-labelling organisations which set criteria to certify products and services with lower environmental burdens and impacts than comparable products with the same function. Currently GEN has 14 eco-labelling organisations as members, including The Blue Angel and the Nordic Swan.
(G) Greenhouse Effect
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The greenhouse effect means the damaging effect of green-house gases in the atmosphere. They allow short-wavelength solar radiation to reach the Earth but retain longer wavelength radiation which causes warming of the atmosphere. The most important greenhouse gases are water vapour and carbon dioxide.
(G) Greenhouse Gases
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As defined in international conventions on climate change, include carbon dioxide, methane and nitrogen oxides, and less significant PFC and HFC compounds and sulphur hexafluoride.
(G) Green Seal
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Green Seal is an American eco-label which is awarded to products that are found to cause less harm to the environment than other similar products.
(g) g/m2 (gsm)
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Both stand for grams per square metre, g/m2 is the correct definition by paper makers but gsm is used much more frequently by printers. This is the primary measurement of the weight of paper, ie 60 g/m2 is a paper of weight 60 grams per square metre, making it obviously lighter than an 80 g/m2 paper.
(G) Gamma
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Measure of how compressed or expanded the dark and light shades become in an image.
(G) Ghosting
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There are two types of ghosting: a) An image that appears as a lighter area on a subsequent print, due to local blanket depressions from previous image areas. b) Spoiling of a print by an image on it of work on the reverse side that has interfered with its drying, so that differences in the trapping of some colours or variations in gloss are apparent.
(G) Glassine
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A hard semi- transparent paper.
(G) Gloss
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Gloss can refer to the reflectivity of paper itself or to the printed result on it. Gloss of paper is measured by using a Gardner gloss meter, which measures reflected light at an angle of 75°, and is expressed in Gardner gloss units – the higher the number, the glossier the paper surface.
(G) Graduated screen
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A ‘screen’ is a series of ink ‘dots’, printed on to a paper, which gives the appearance of a solid colour. The depth of screen colour can be deepened by increasing the dot frequency (see dpi), or the converse. A graduated screen is one where the dpi is varied across the screen so that you get a fading/deepening effect across the printing.
(G) Grammage
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Another expression of gsm or g/m2, used to express the weight of paper or board (see g/m2).
(G) Graphic papers
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Papers for printing and writing.
(G) Gravure printing
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Process in which recesses on a printing cylinder are filled with ink and the surplus removed by a blade. The paper contacts the cylinder and ‘lifts’ the ink from the recesses before depositing it on the paper. Generally used for long run printing, eg magazines and catalogues, because of the high cost of the cylinders.
(G) Greaseproof paper
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Paper that has a high resistance to penetration by grease or fats from foodstuffs. The paper is produced by prolonged beating in the pulp stage.
(G) Green paper
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Immature paper that has not been conditioned or had the opportunity to mature naturally.
(G) Greyscale
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The ‘greyscale’ is literally a strip of paper showing tones from white to black. ‘Greyscale’ refers to a range of neutral colours – an 8 bit a file can have 256 levels of grey (including black and white). A colour monitor uses 8 bits for each pixel,displaying 2 to the 8th power (256) different colours or shades of grey.
(G) Grey board
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A board made entirely from waste paper. It can be lined or unlined and is used for a variety of packaging purposes.
(G) Gripper
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A device on a printing machine for holding the sheet during the printing or finishing process.
(G) Grain direction
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A term applied to thr machine direction of papers or boards, as opposed to the cross direction.
