Makeready is literally the process of making the press ready to print. Makeready is more than oiling and inking the press, and making sure the form is locked up securely; it is,

in the narrowest sense . . the diagnosis of defects, the selection of the best remedies for correcting the defects, and the application of those remedies, so that the form will produce the best possible print on the sheet. The defects generally may be classified as: imperfections in the form, the wrong kind or amount or improper distribution of the ink, the wrong amount or improper distribution of printing pressure, slurs, or poor register.¹

In this video, Harold Kyle of Boxcar Press demonstrates makeready for fine tuning impression on a platen press

Tools for effective makeready

Loupe or magnifying glass
Knife
Paste or light glue
Tissue

Regulating Impression

Underlay

An underlay is a thickness of paper pasted to the base of a plate to make the plate level and type-high or, in some cases, to raise a heavy printing surface slightly above type-high. Underlays should only be used when the plate is not level and type high.²

Interlay

Overlay

An overlay is a trial impression sheet placed in the packing so that the form will print exactly upon it, line for line. Thicknesses of paper are pasted to this sheet where needed to add pressure to weak printing areas; other thicknesses may be peeled or cut away to reduce pressure on areas that are printing too heavily. The overlay is used for more delicate pressure adjustments than the underlay. . . and may be started only after the imposition and underlays are satisfactory.³