lead out

To lead out is to increase the vertical space between lines of type by inserting thin strips of lead metal, called leads or slugs, between the lines in a composing stick or chase. In letterpress printing, when metal type is set by hand, the compositor places individual character sorts into a composing stick, then arranges complete lines into a galley or chase. Once the text is assembled, leads (pronounced "ledz") are inserted horizontally into the gaps above and below each line to adjust spacing and improve readability or to fill out a page to the required depth.

Lead stock came in standard thicknesses: 2-point, 4-point, 6-point, and 12-point (a point being 1/72 inch). A 2-point lead is barely visible as spacing; a 12-point lead, called a "nonpareil," creates a substantial gap. Compositors chose thickness based on the desired line spacing, type size, and design intent. A compositor might lead out a page of 10-point type with 2-point leads for tight spacing, or 4-point for a more open feel. The practice allowed precise control without casting new type in different sizes.

Related terms include "leaded" (text with leads inserted) versus "solid" (lines touching), and "leading" (pronounced "LED-ing"), which refers both to the process and the resulting line spacing measurement. A printer might specify "10 on 12" to mean 10-point type on 12-point leading, implying 2-point leads inserted between lines. Slugs, which are thicker metal spacers ranging from 6-point to 12-point, served similar purposes but were sometimes used for larger gaps or paragraph breaks.

The physical consequence of leading out was increased pressure on the type itself and on the printing press. Lead is soft and malleable; repeated inking and impression could deform leads, causing uneven spacing over time. Compositors had to watch for damaged leads and replace them before they affected print quality. In high-volume work, leads wore quickly and represented an ongoing cost.

The term survives in digital typography as "leading," though the concept has been abstracted. Modern designers adjust leading in points or as a percentage of type size without touching metal. The word persists as a ghost of the material process, a reminder that typography was once a physical craft dependent on precise metal measurement and hand placement.