height to paper
In typefounding, the length of a type from its face to its foot.
height to paper: the vertical dimension that makes type lock tight
Height to paper is the precise vertical distance from the printing face of a piece of type to the bottom of its body, or foot. This measurement determines whether type will print at all, and whether it will print evenly across a full forme. In letterpress printing, all type must reach exactly the same height so that when locked into a chase and run through the press, every character strikes the paper with uniform pressure.
The standard height to paper in Anglo-American printing has been 0.918 inches (23.317 mm) since the 19th century, though European foundries sometimes cast to slightly different standards. A type that is even 0.005 inches too short will not touch the paper; one that is too tall risks damaging the press or printing a darker impression than surrounding type. Founders measured this dimension with great precision using special gauges, and printers maintained it by careful storage and handling.
Where variation happens
Wood type and display faces were sometimes cast or mounted to non-standard heights. Display metal type made for art printing, rules, ornaments, and foundry leads and slugs all required conformity to the established height, or the printer had to shim or dress them at the stone. Type that was heavily worn or damaged might be dressed down by a foundry to restore its usefulness, reducing its total height and requiring compensation during composition.
Hand composition required constant vigilance: a single piece of type set one or two thousandths of an inch low would print lighter or not at all. Linotype machines and Monotype casters were engineered to produce slugs and individual types at exact height to paper specifications. The rise of phototype and digital composition eliminated this dimensional concern entirely, which is one reason height to paper is now mainly a historical concern.
Understanding this term is essential when working with salvaged or antique metal type, or when operating a hand press with found sorts. A mixed collection of type from different foundries or eras may have slight height variations that affect print quality. Printers working with metal type still speak of height to paper when diagnosing uneven impressions or explaining why reclaimed type may need mechanical correction before use.