Acetate
A transparent sheet placed over originals or artwork, allowing the designer to write instructions and\or indicate a second colour for placement.

Acid-free Paper
Papermade from pulp containing little or no acid so it resists deterioration from age. Also called alkaline paper, archival paper, neutral pH paper, permanent paper and thesis paper.

Acid Resist
An acid-proof protective coating applied to metal plates prior to etching.

Additive Colour
colour produced by light falling onto a surface, as compared to subtractive colour. The additive primary colours are red, green and blue.

A4 Paper
ISO paper size 210 x 297mm used for Letterhead.

Against the Grain
At right angles to the grain direction of the paper being used, as compared to with the grain. Also called across the grain and cross grain. See also Grain Direction.

Airbrush
Pen-shaped tool that sprays a fine mist of ink or paint to retouch photos and create continuous-tone illustrations.

Alteration
Any change made by the customer after copy or artwork has been given to the service bureau, separator or printer. The change could be in copy, specifications or both. Also called AA, author alteration and customer alteration.

Anodized Plate
An offset printing plate having a treated surface in order to reduce wear for extended use.

Anti-offset Powder
Fine powder lightly sprayed over the printed surface of coated paper as sheets leave a press. Also called dust, offset powder, powder and spray powder.

Antique Paper
Roughest finish offered on offset paper.

Aqueous Coating
Coating in a water base and applied like ink by a printing press to protect and enhance the printing underneath.

Artwork
All original copy, including type, photos and illustrations, intended for printing. Also called art.

Author's Alterations (AA's)
At the proofing stage, changes that the client requests to be made concerning original art provided. AA's are considered an additional cost to the client usually.