Glossary

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A international sizes
A size, RA size, SRA size, IPS. The A series of sizes uses a parent sheet AO 841x1189 mm, a sheet with an area of 1 square metre and the sides in proportion of the square root of two. This proportion was selected so when the sheet is folded or cut in two the sides are still in the same proportion. Sixteen A4 sheets can be cut exactly from an A0 sheet. For processing an allowance is added to the length and breadth. The RA series adds approximately 2.5% to allow for trimming and grip, the SRA series adds about 15% allows for bleed, fold, trim and grip. The B series of sizes are not as well established. They are based on BO a size of 1000x1414, B4 is 250x354 and B5 177x250mm. The common B1 size stocked varies from 700x1000 to 720x1020, unfortunately not all B1 sizes presses can accept 720x1020.
A0
841 x 1189, 860 x 1120, 900 x 1280
A1
594 x 840, 610 x 860, 640 x 900, 650 x 910
A2
420 x 594, 430 x 610, 450 x 640, 455 x 650
A3
297 x 420, 310 x 430, 320 x 450
A4
210 x 297
ABCD Waste
Classification System used by some of the Paper Industry to define types of waste used to make a particular recycled paper. Although not perfect, it gives some indication of technical and environmental quality.
Absorption
In paper, the property that causes it to take up liquids or vapours in contact with it. In optics, the partial suppression of light through a transparent or translucent material.
Acid free
A paper manufactured to a neutral pH reading. Primarily used for permanent records and to protect materials when contact with paper acidity would be harmful.
Acid Rain
A combination of atmospheric moisture, airborne sulphur and nitrogen oxides to form sulphuric and nitric acids.
Additive primaries
In colour reproduction, red, green and blue.When lights of these colours are added together, they produce the sensation of white light.
Against the grain
Folding or feeding paper at right angles to the grain direction of the paper.
Air brush
Used to correct and obtain tone or graduated tone effects.
Alkaline paper
Paper made with a synthetic alkaline size, and alkaline filler like calcium carbonate, which gives the paper over four times the life (200 years) of acid-sized papers (40-50 years).
AM (amplitude modulation)
Halftone screening, as opposed to FM screening, has dots of variable size with equal spacing between dot centres (see Halftone).
American quarto
The usual size of office documents in the USA as opposed to the metric systems A4 or B5. American Quarto is 8.5 x 11 inches, (equivalent metric size is 216 x 279 mm.)
American substance
The industry in the USA uses imperial measurement in inches and pounds and has its own system of measuring the basis weight of paper. The size used to calculate the basis weight varies dependent upon the paper type. The table below tries to equate the systems. Metric Weight equivalents of popular American substances are as follows: 24 lb Writing 90 gsm, 60lb Text 89 gsm, 28lb Writing 105 gsm, 70 lb Text 104 gsm, 80 lb Text 118 gsm, 100 lb Text 148 gsm, 65 lb Cover 176 gsm, 80 lb Cover 216 gsm, 100 lb Cover 270 gsm, 130 lb Cover 352 gsm.
Analogue colour proof
Off-press colour proof made from separation films.
Anti-halation backing
In photography, coating applied to back of film to prevent halation.
Anti-offset or set-off spray
In printing, dry spray of finely powdered starch used on press to prevent wet ink from transferring from the top of one sheet to the bottom of the next sheet.
Antique finish
A term describing the surface, usually on book and cover papers that have a natural rough finish.
AOX
Reported as the total amount of chlorine bound to organic compounds in waste water.
Aperture
In photography, lens opening or lens stops expressed as an f/no. Such as f/22.
Apochromatic
In photography, colour-corrected lenses, which focus the three, colours, blue, green and red, in the same plane.
Art
All illustration copy used in preparing a job for printing.
Ascender
That part of a lower case letter, which rises above the main body, as in "b".
Automatic processor
In photography, machine to automatically develop, fix wash and dry exposed photographic film. In plate making, machine to develop, rinse, gum and dry printing plates.