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 Rready: Process of adjusting final plate on the press to fine tune or modify plate surface.

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.

Mask (2): A photo negative or positive used in the color separation process to color correct. Reference, PRINTING, mask.

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 coated paper finish that goes through minimal calendaring. Reference, calendaring.

Measure: The width of type as measured in picas. Reference, picas.

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

Metropolitan Service Area: A group of ZIP codes usually in close proximity defining a large metropolitan area (e.g. New York City or Los Angeles).

Midtone Dot: Commonly taken as the area between highlight and shadow area of a subject's face in halftone image.

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

Molleton: A cotton fabric used on the dampening rollers of a printing press.

Molybdate Orange: An ink pigment made from precipitating lead molybdate, lead sulfate and lead chromate.

Mottle: A term used to describe spotty or uneven ink absorption.

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

Mullen Testing: A specific test of tensile paper strength; an important factor if web presses are used for printing.