Hairline rule: the thinnest rule that can be printed.

Hairlines: the thinnest of the strokes in a typeface.

Half Up: artwork one and a half times the size which it will be reproduced.

Halftone: an illustration reproduced by breaking down the original tone into a pattern of dots of varying size. Light areas have small dots and darker areas or shadows have larger dots.

Halftone Screen: a glass plate or film placed between the original photograph and the film to be exposed. The screen carries a network of parallel lines. The number of lines to the inch controls the coarseness of the final dot formation. The screen used depends on the printing process and the paper to be used, the higher the quality the more lines can be used.

Hanging Punctuation: punctuation that is allowed to fall outside the margins instead of staying within the measure of the text.

Hardback: a case bound book with a separate stiff board cover.

Heat-Set Drying: drying a web or sheet of paper or board by passing it through a drying unit which forms part of the machine. Special heat-setting inks have to be used.

Hexachrome: a Pantone ®colour matching process using 4 process colours plus a vibrant orange and green (6 colours) giving a wider range of colour reproduction with greater depth than 4 colour process alone.

Hickies:  a dust particle sticking to the printing plate or blanket which appears on the printed sheet as a dark spot surrounded by a halo.

Hot-Foil: a printing technique using very thin aluminium foil in a variety of metallic colours, such as gold, silver, red and blue. The metallic foil is released from carrier base onto a substrate by the application of heat and pressure from a metal printing plate which bears the image to be hot-foiled.

House Style: the style of preferred spelling, punctuation, hyphenation and indentation used in a publishing house or by a particular publication to ensure consistent typesetting.

H.S.W.O.: heat set web offset. A rotary printing process using heat to set the ink. A cylinder transferring the image from the printing plate to blanket to paper at speeds of 30000 or more impressions per hour.