M
Symbol for magenta in four-color printing.

M Weight
The actual weight of 1000 sheets of any given size of paper.

Machine Coated
Paper that has had a coating applied to either one or two of its sides during the papermaking process.

Machine Direction
An alternate term for grain direction.

Machine Finish
A paper finish that results from the interaction of the paper with the Fourdrinier process as opposed to post machine embossing. Reference, Fourdrinier.

Magnetic Black
Black pigments containing black iron oxides, used for magnetic ink character recognition.

Make-Ready
(1) All activities required to prepare a press or other machine to function for a specific printing or bindery job, as compared to production run. Also called setup. (2) Paper used in the makeready process at any stage in production. Makeready paper is part of waste or spoilage.

Margin
Imprinted space around edge of page.

Mark-up
To write up instructions, as on a dummy.

Mask 
(1) The blocking out of a portion of the printing plate during the exposure process. Also called knock out. (2) A photo negative or positive used in the color separation process to color correct.

Match Print
Photographic proof made from all color flats and form composite proof showing color quality as well as accuracy, layout, and imposition before plates are made.

Matte Finish
A flat (not glossy) finish on coated printing paper.  

Mechanical
A term used to describe finished artwork that is camera ready for reproduction, including all type, photos, illustrations, and instructions.

Midtones 
In a photograph or illustration, tones created by dots between 30 percent and 70 percent of coverage, as compared to highlights and shadows.

Mock Up
A reproduction of the original printed matter and possibly containing instructions or direction.

Moire
An undesirable halftone pattern produced by the incorrect angles of overprinting halftone screens.

Mottle
Spotty or uneven ink absorption.  Also called sinkage.

Mull
Coarse muslin glue placed on the back of book or pads for strengthening.