Before printing from a plate, a proof is taken on an impression sheet from which portions which print too fully are cut away, and others which do not give a clear impression are patched up with portions cut from other sheets. The sheet thus treated is placed on the tympan of the press or on the impression cylinder, and is fixed there, as an overlay, to correct the inequalities in the printing surface. It seems finicky work, and is now largely done by mechanical processes. Make-ready is of special importance in typographical stamp printing where the extremely fine lines have to be given their full value, not just on one stamp, but on each of the 100, 240, or more units on a plate.

It serves to produce some philatelic curios, but is more useful to collectors in distinguishing different printings, and the work of different printers.

In addition to the overlay, there is often an underlay of thicknesses of paper on the under side of a plate.