- KRAFT PAPER Paper made from a type of chemical wood pulp; it may be bleached or unbleached and produces a strong paper which is used for wrapping and packaging; the term comes from the German word for strong.
- KRAFT PULP Chemical wood pulp produced by digesting the wood by the sulphate process. Originally a strong, unbleacbed coniferous pulp for packaging papers. Kraft pulp has now spread into the realms of bleached pulps from both coniferous and deciduous woods for printing papers.
- LABEL PAPERS A large variety of plain or coloured body papers which are made to be gummed, or for application of a self-adhesive material, and subsequently cut into a vast number of shapes and sizes depending on end use and surface application.
- LAID LINES A Continuous watermark consisting of very close parallel lines, generally associated with spaced lines (chain lines) at right angles to these.
- LAMINATE Overlay of sheets of paper or board either with other paper or board or with other materials such as plastic or metal foil to form a product with special qualities.
- LICK COATING A light form of mineral coating, achieved by supplying the surface sizing press of the paper making machine with coating material instead of normal surface sizing solution.
- LIGNIN A substance in wood which binds its fibres together and reinforces its structure. Lignin is removed in the manufacture of chemical pulp.
- LITHOGRAPHIC PRINTING A planographic printing process in which the non-image areas of the printing plate are made hydrophillic and the image areas are made hydrophobic. LOADING White, inert mineral matter such as China Clay, Calcium Carbonate, Titanium Dioxide etc. added to the papermaking stock to confer opacity on the finished paper. Loading may also beneficially affect flatness and dimensional stability.
- LONG GRAIN See Short Grain
- LOOK-THROUGH The appearance of the paper when held up to transmitted light. It discloses whether the formation is even and uniform or lumpy and “wild”. For book publishing papers, a regular, even look through is desirable, indicating a well made, uniform sheet.
- MACHINE CLOTHING Fabrics of various types employed on the paper machine to carry the web and perform other functions. It includes the machine wire and wet and dry felts which may be composed of natural or synthetic materials.
- MACHINE COATING See ON-MACHINE COATING MACHINE DECKLE The overall width of the wet web as it leaves the forming zone of the paper making machine. Note: Often used incorrectly to indicate the width of the web at the dry end of the machine.
- MACHINE DIRECTION The direction the wire mesh on a paper making machine is travelling; over 50% of the fibres position themselves with their lengths parallel to this direction.
- MACHINE FILL OR DECKLE FILL The width of the paper making machine taken up by a making of paper. For reasons of economy it should approach so far as possible the maximum trimmed width of the machine.
- MACHINE FINISHED PAPER (MF) Paper which has been made reasonably smooth by means of calender stacks at the end of the paper making machine.
- MACHINE-GLAZED PAPER (MG) Paper which has had one side made smooth and glossy by drying in contact with a large, heated, polished metal cylinder which forms part of the drying section of the machine. The other side of the paper remains relatively rough.
- MACHINE WIRE The fabric used for converting the dilute stock into a formed sheet by permitting drainage of water and retention of the other elements of the stock. It may consist of a woven wire cloth or a plastics or similar fabric which contains a suitable pattern of perforations.
- MANIFOLD See Airmail Paper
- MAXIMUM TRIMMED WIDTH The greatest width of usable paper it is possible to make on a given paper making machine, i.e. the full width less the necessaiy trim to give clean edges. It is not possible to specify sizes which, in aggregate, exceed this width.
- MECHANICAL PAPER Paper, the furnish of which contains a substantial proportion of mechanical wood pulp.
- MECHANICAL PRINTINGS Printing papers made chiefly from pulp produced by the groundwood method. By this method of pulp production the wood is mechanically ground with water to separate the fibres and produce pulp. This grade may be coated on or off the machine, machine or supercalendered.
- MECHANICAL WOODPULP (GROUNDWOOD) Pulp produced from wood solely by mechanical means such as grinding or refining.
- MICRO-CREPING A process for compacting the paper web in the machine direction and imparting a high degree of stretchability by passing the web between a roll and, for example, an endless robber blanket. The blanket is extended immediately before the point of contact with the web and allowed to return to its normal state during the passage of the web through the space between the roll and the rubber blanket. A typical example of micro-crêping is the Clupak process.
- MICR PAPER (Magnetic Ink Character Recognition Paper) Usually a high-quality bond paper with good surface characteristics and dimensional stability for printing with magnetic inks for computer sorting.
- MIDDLE (OF BOARD) Furnish layer of a hoard situated between the two external furnish layers, or between the underliners, or between an underliner and an external furnish layer.
- 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.
- MIS-REGISTER The appearance of a printed image out of its correct position.
- MOULD MADE Originally, paper made by hand by the traditional method of paper moulds, usually from rag pulp. Today, mould made papers are high quality grades made on a cylinder mould machine, as opposed to a Fourdrinier or other type of machine, and may be made with or without deckle edges.
- MULTIPLE BOARD MACHINE A machine in which a number of plies of paper can be combined together in the wet state to produce thick cardboard.