In letterpress printing, the compositor arranges pages of type inside this rigid metal rectangle on an imposing stone. Wooden or metal furniture is placed around the type, and expanding quoins are tightened to lock everything into a solid, immovable mass. Once locked up, the entire assembly can be safely lifted and mounted onto the bed of the printing press.
Lock up the form tightly in the chase, because if a single letter drops out while we move it to the platen, we've to start over.
Related terms
Furniture
Blocks of wood or metal used to fill blank spaces in a chase and establish page margins.
Quoin
An expandable wedge used to lock metal type securely inside a chase.
Form
A complete body of assembled type and blocks locked into a chase ready for printing.
Imposing stone
A flat, heavy surface used for assembling and locking up metal type.