| M | An abbreviation for a quantitiy of 1,000 sheets of paper, or number of impressions. |
| Machine coated | Paper which is coated on one or both sides on a paper making machine. |
| Machine direction | Indicates the direction of forward movement on the press. |
| Machine finish | A grade of paper available for use in the finish that comes from the paper machine. |
| Magenta | Hue of a subtractive primary and a four colour process ink. It reflects or transmits blue and red light whilst absorbing green light. |
| Magenta screen | A dyed contact screen used for making halftones. |
| Magnetic cylinder | A steel based cylinder having a series of permanent magnets inserted around its periphery. It may be used to retain flexibles dies in position and also metal backed printing plates. |
| Magnetic die | A steel plate of some nominal 0.4mm in thickness upon which the required die cutting configuration has been etched. Due to the thickness the plate is flexible and may therefore be used in either flat or rotary formats. |
| Magnetic storage | Any disc, film, tape, drum, or core that is used to store digital information. |
| Magnetography | Follows the concept of electron deposition except that a magnetic drum, a magnetic charge and special magnetic toners are used to produce the printed image. |
| Makeready | Embraces all the activities involved in getting ready all the components prior to running a job on the label press. |
| Malachite test | A green coloured die which when mixed with water may be used to check for any penetration of the silicone coating during die cutting. |
| Mandrel | A shaft upon which cylinders or other items are located for support during a print run. Also applies to unwind and rewind shafts onto which rolls of material or finished labels may be wound. |
| Manila | Describes the colour and the qualities of a paper made from strong fibre materials. |
| Mask | The inactive area of a bitmapped image that will not respond to changes. |
| Masking | Covering part of an image during exposure or etching. A method of attaining differential exposure within a section of a plate or film. |
| Master roll | The roll of paper or laminate as it comes off the production machine prior to being trimmed and slit. |
| Mat finish | A dull finish without gloss or luster. |
| Material | Used to describe either plastic or paper in mono or laminated form. |
| Material memory | The phenomena whereby a material that has been produced under tension retains a memory of its natural dimension and returns to it once the tension is removed. |
| Matrix | The skeleton of face material around die cut labels. |
| Medium pressure mercury lamps | This type of lamp emits at the normal mercury spectra. Such lamps may be modified with ion and gallium which gives them a different spectra and a shorter life. Power emitted may be between 120 and 240 watts per cm. |
| Megabyte (Mb) | One million bytes of information. |
| Membrane switch | Self-contained sealed film lamination, usually screen printed with conductive inks that provide trace paths for electrical currents. |
| Memory | The property of a material that attempts to return it to its original configuration once released from tension. |
| Menu | A method for selecting alternative functions displayed as a list on a workstation screen. Selected via a mouse, key, or sequence of keys. |
| Mesh size | Refers to the size of gaps in the mesh for the ink to be pressed through in screen printing (screen process). |
| Metal foil | Thin, flexible layer of metal, often aluminium, used as a label material. The thinner gauges may be laminated to a paper support for added strength. |
| Metalized film | A clear filmic material which has been passed through a special chamber and had a thin layer of vaporized metal electronically applied to the surface. |
| Metalized paper | A laquered paper which has had a thin layer of metal depositited on the surface. |
| Meyer rod | A wire wound steel rod which is used to control the thickness of any coating being applied to a paper or filmic material. The diameter of the wire controls the flow of colour or adhesive onto the surface. |
| MICR | Magnetic Ink Character Recognition. The process of machine reading of printed characters. |
| Micrometer | A device used to measure thickness or diameter down to 0.001mm or less. |
| Middle tones | The tonal range between highlights and shadows of a photograph or reproduction. |
| Mill roll | A roll of paper, film, or foil, as it is delivered to the printer from the mill. |
| Millipoise | The unit of viscosity measurement. 1/100th of a poise. |
| Minimum application temperature | The lowest temperature at which a self-adhesive label may be applied whilst retaining its initial tack. |
| MIS | Management Information System. |
| Miscible | Mutually soluble ingedients which are capable of being mixed. |
| Misting | Minute droplets of liquid are thrown off as rollers rotate. Such effect constitutes a health hazard quite apart from the waste of medium and the fact that it can form an unsatisfactory build-up on parts of the coating line or printing press. |
| Modem | An add-on device that allows computers to communicate through telephone lines. |
| Moire | Unwanted wavy effect produced in printing when halftone screen patterns become visible due to the clashing of screen angles of different colours or images. |
| Moisture content | The amount of moisture retained in a material. (humidity). |
| Moisture equilibrium | The condition of a material in which moisture is neither being absorbed or lost to the surrounding atmosphere. |
| Moisture proof | The property of a material that makes it almost impervious to water vapour. |
| Moisture resistance | The property of a material which helps to resist the intake of moisture. |
| Monomer | Constituent of oligomers and polymers. |
| Mottle | A spotty or uneven appearance. Noticed in solids printed from over thinned ink. |
| Mould release agents | An agent, often silicone based, which is used to speed up the removal of moulded items on the completion of moulding. When a proportion of such agents remains upon the surface of the moulding the keying of the adhesive may be adversely effected. |
| Mounting | The process of mounting plates or flexible dies. Ensuring colour to colour and colour to die register. |
| Mounting tape | Thin double sided material coated with strong adhesive and used for mounting printing plates. |
| Multi-process | A printing press laid out to print from more than one process at a single pass through the press. The addition of a varnishing or lacquering station following the printing activity is not considered as multi-process. |
| Multi-roll coater | A coating head designed to dispence a measured amount of silicone or adhesive by passing it through a series of rollers until the required amount passes to the final applicator roll from where it is transferred onto the substrate. |
| Multi labelling | Refers to the situation when a number of labels are applied to a container at the same time. Usually involves using linked applicators, one for each label. |
| Mylar | A film having high mechanical strength and dimensionable stability |