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PULP AND PAPER DICTIONARY

This page contains definitions of the terms, words and phrase commonly used in pulp and papermaking, printing, converting and paper trading.

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M WEIGHT                    The weight of one thousand sheets of paper, any size; or double the ream weight.

M2 YIELD/TON             A measure of the surface area of paper/paperboard which is obtained from a ton of paper.

MACHINE CHEST        Usually the last large chest or tank that contains thick-stock pulp before it is made into paper.

MACHINE CLOTHING OR PAPER MACHINE CLOTHING  Fabrics of various types employed on the paper machine to carry the web and perform other functions. It includes the machine wire, dandy roll cover, press felts and dryer felts etc., which may be composed of natural or synthetic materials.

MACHINE CREPE        Crepe paper produced on the paper machine, and not as a secondary option.

MACHINE DIRECTION  The direction of the web through the paper machine.

MACHINE DIRECTION (MD)   Parallel to the direction of the flow of paper through a machine.  Also see cross direction (CD) and Z direction (ZD).

MACHINE FINISH         Finished produced on the paper as it leaves either the machine or the calendar stack. For increased printability, or smoothness when used as a liner, etc.

MACHINE GLAZED      Machine glazed. Paper with a glossy finish on one side produced on the paper machine by a Yankee cylinder.

MACHINE SPEED        The rate at which paper machine runs, expressed as m/min or ft/min.

MACHINE WIDTH         Width of the paper web in the paper machine.

MALE      When applied to an embossing pattern that is engraved into the surface of an embossing roller or plate, "male" means that the pattern is composed of elements that are raised up from a flat background, like mesas in a desert.  A female pattern is composed of elements that are recessed into a flat background, like potholes in pavement.  However, many patterns are too complex to be described overall either as male or as female.  These terms, male and female, work better when applied to a single embossing element.

MALLEABLE     Literally, cabable of being worked by hammering, so that the material's shape can be extended by the application of mechanical force without breakage.  This shape change should be permanent.  Some materials must be heated to have this property.  A more modern term is plasticity.

MANIFOLD PAPER      A light weight bond paper used for making carbon or manifold copies or for airmail correspondence.

MANILA                         A semi-bleached chemical sulphate paper. Not as strong as Kraft, but have better printing qualities.

MANUFACTURING ORDER  Also known as making order. A quantity of paper manufactured to custom specifications, such as a special weight, colour, or size not available as a standard stocking item.

MARKET PULP            Pulp which is made to be used elsewhere for the production of paper. Usually dried to reduce freight costs but may be "wet lap" ( 50% water).

MARBLING                   Addition of strongly stained fibres to the stock to give the paper a marbled appearance.

MARRYING NIP OR SHOE     The part of the laminating process where the layers to be bonded are pressed together to make the adhesive form a better bond.  The best way to do this is to apply pressure only at the glue-bond points, and avoid crushing any other part of the product.  In nested lamination, this is done by using a marrying roll that is pressed against the same embossing roller that carried the paper which received the glue from the adhesive applicator.  In pin-to-pin lamination, this is done in the laminating nip , which is where the two embossing rollers come into contact with each other.  With random registration , it is not possible to avoid crushing unbonded areas of the product.

MATCHED EMBOSSING OR ENGRAVING    An embossing or engraving nip where the surfaces of the two rollers are perfectly matched, so that wherever the surface of one roller is raised by some distance, the corresponding surface on the other roller is recessed by the same distance.  When the rollers are fully engaged, there is complete contact at every point along the nip line.  In matched embossing, both rollers are engraved (as in steel-to-steel embossing), and one roller is usually made from the other in a matched steel engraving process using acid etching.  In actual embossing practice, absolutely perfect matching is often avoided, in order to improve runnability, by creating a small gap between the rollers in selected areas of the pattern. 

MATTE FINISH             A dull, clay-coated paper without gloss or lustre.

MAXIMUM TRIMMED WIDTH  The greatest width of usable paper that is possible to make on a given paper making machine, i.e. the full width less the necessary trim to give clean edges. There is 3-10% width shrinkage (depending on freeness of stock) in dryers. It is not possible to specify sizes which, in aggregate, exceed this width.

MD   Acronym for machine direction.

MDT   Acronym for Machine Direction Tensile strength.  See tensile strength.

MECHANICAL PAPER This paper contains mechanical pulp, thermomechanical pulp (TMP) or chemithermo-mechanical pulp (CTMP) and also chemical pulp. The shares of chemical and mechanical pulp vary depending on the application. Highly mechanical papers such as newsprint tend to yellow more rapidly if exposed to light and oxygen than woodfree papers so that they are mainly used for short-lived products. In printing papers the mechanical pulp improves opacity.

MECHANICAL PULP    Pulp produced by mechanically grinding logs or wood chips. It is used mainly for newsprint and as an ingredient of base stock for lower grade printing papers.

MEDIUM DENSITY FIBERBOARD (MDF)   A composite panel made from wood fibres and resin and formed under pressure and heat. MDF has a smooth surface and good machinability, and is used for furniture, cabinetry and millwork.

MESH                            Count of wires per inch for metal and/or plastic screen used in paper mill.

METAMERISM              The tendency of colours to appear different under different light sources such as fluorescent or natural sunlight.

MG MACHINE               A paper machine incorporating a Yankee or a MG drying cylinder in the drying section to produce MG paper.

MICRO CRYSTALLINE CELLULOSE PULP  Like Ethers Pulps, these pulps are used in thickening and pharmaceutical applications, particularly in construction of tablets and other non-capsular pills.

MICRO EMBOSSING   Embossing with a very fine pattern, sometimes with the purpose of simulating the wiremark appearance of a TAD product, especially for bath tissue or paper towel.  Pattern fineness is often characterized by the density, or number of elements per unit area.  Micro embossing is sometimes used as a background for spot embossing and/or quilting .

MIL (or mm)                  One thousandth of an inch.

MILL                              The physical site where paper is manufactured; also refers to a company that manufactures paper.

MILL BROKE                Paper generated at the paper mill prior to completion of the manufacturing process. Wet mill broke originates at the wet end of the papermaking machine, while dry mill broke comes from the dry end of the papermaking machine.

MILLBOARD                 A thick, dense, homogeneous board, for book production, made generally from wastepaper, on a special board making machine one sheet at a time. Used in binding case bound books, ledgers etc. as binders’ boards.

MINERAL FILLER         Materials such as chalk and china clay that are added to paper in order to change its density or improve its surface and optical properties.

MIXED OFFICE WASTE  Wastepaper generated from offices, such as letters, memos, invoices, etc. which are collected and sorted for paper qualities. This is the major source of post consumer fibre.

MODIFIED STARCH    Papermaking starch that has been processed generally by oxidation, to achieve lower viscosity or chemical characteristics which are beneficial in use as an additive in papermaking.

MOISTURE CONTENT  The amount of moisture or water in a sheet of paper, expressed in percent. 6 to 7% is desirable.

MOISTURE RESISTANT  Paper Treated with asphalt, wax, plastic, etc. to control penetration of moisture.

MOLDING PULP          Pulp, which is used for producing pulp-based or fibrous products by pressing; example products: egg packages, trays and boxes for fruits and vegetables.

MORDANT                    Chemical added to pulp to improve the fixation of dyes to the fibre.

MOTTLE                       A random non-uniformity in the visual density, colour or gloss of a printed area; also known as orange peel, back-trap mottle, wet-trap mottle, pigment flocculation, striations, etc.

MOTTLING FIBRE      Heavily dyed fibres added to a different colour stock furnish to produce characteristic surface effects.

MULLEN                       Measurement of the force required, in pounds per square inch, to rupture a sheet of Kraft paper. Also known as bursting strength.

MULTI-STAGE COOKING  Chemical pulping process in which the alkalinity of the cooking liquor is varied by charging the alkali in several stages.

MULTIPLY BOARD MACHINE  A machine in which a number of plies of paper can be combined together in the wet state to produce thick paperboard..

MULTIPLY PAPER MAKING PROCESS  A paper/board making process in which different layers of fibres are deposited one over the other to form the sheet. The multiply process is used to make the optimum use of various type of fibres available. It is also used to make heavy basis weight papers.