A quoin is a device used to lock printing type in a chase in

letterpress Letterpress printing is a technique of relief printing for producing many copies by repeated direct impression of an inked, raised surface against individual sheets of paper or a continuous roll of paper. A worker composes and locks movable t ...

printing. Quoins are pairs of wedges, facing opposite directions. A wrench or quoin key forces them together.

References

Letterpress printing Relief printing {{Typ-stub