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Lexikon
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A • B • C • D • E • F • G • H • I • J • K • L • M
N • O • P • Q • R • S • T • U • V • W • X • Y • Z |
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Bleed
This printing term refers to printed matter which runs off the edge of the paper as part of the design. Normally, 3mm is allowed to cover variations in folding, trimming, binding etc. Printers and copiers do not generally print to the edge of a sheet, so the design should avoid this feature. If the design requires bleed, the solution is to print on a larger sheet, e.g. A3+ or SRA 3 and trim the product.
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Bending Stiffness
The stiffness of paper is usually measured as the bending moment, which expresses the force needed to bend a paper strip to a defined angle. As the stiffness of paper is higher in the machine direction, it is essential to have a certain stiffness in the cross direction in order to avoid problems. Stiffness can affect the runability of paper in the printing press, e.g. a laser printer, as well as in converting processes such as binding or folding. Paper is about three times stiffer lengthwise than across its width. The stiffness is higher lengthwise than across its width.
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Brightness
The ISO brightness of pulp and paper is defined as the directional reflectance of light at a wavelength of 457 nm. This property was developed to measure the effect of pulp bleaching. It is not a good measure of perceived whiteness since it disregards a large part of the visible spectrum of light. For this reason the paper industry is gradually adopting the CIE whiteness index to define the whiteness of its paper.
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Bulk
Bulk is defined as the paper volume per unit mass. High bulk is particularly important for paper of low basis weights, representing a voluminous and normally fairly stiff paper.
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Basis Weight
The basis weight or grammage of paper is the mass per unit area, usually one square metre. For example, newsprint has a basis weight of about 45 g/m² and copy paper one of 80 g/m². Coated fine papers come in a wide basis weight range of 80 g/m2 to 300 g/m² and coated graphic board in the range of 200 g/m² to 500 g/m². The grammage is the mass in grams per square metre of paper.
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