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.

Adsorbable Organic Halogen Compounds(AOX) Reported as the total amount of chlorine bound to organic compounds in waste water.

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).

Alternative Fibre

Paper made from fibre that is sourced from alternatives to wood.  These include Bagasse (sugar cane), cotton, hemp and bamboo.  Raleigh products containing alternative fibre include Harvest Recycled (60% sugar cane) and Strathmore Writing (25% cotton content). The visual characteristics of these stocks are often indistinguishable from traditional wood based products.

AM (amplitude modulation) Halftone screening, as opposed to FM screening, has dots of variable size with equal spacing between dot centres (see Halftone).

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.

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.)

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.

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.