Select the first letter of the word from the list above to jump to appropriate section
of the glossary. If the term you are looking for starts with a digit or symbol, choose the
extent to which a paper will take up and hold a liquid.
PAPER In principle, paper which
does not contain any free acid. Special precautions are taken
during manufacture to eliminate any active acid that might be
present in the furnish.
A mineral, chemical or dye added to pulp and coatings to give
it special qualities such as opacity.
PAPER Paper dried by exposure to air, generally warm.
PULP Technically, pulp of which the moisture content
is in equilibrium with the ambient atmosphere. Commercially,
pulp at a theoretical moisture content agreed between the buyer
and the seller (e.g. 10 per cent is common).
COATED PAPER Paper coated by a process where the freshly
applied wet coating is smoothed and the excess removed by means
of a jet of air discharged from a slit orifice placed at an
angle to the web.
PAPER Paper made in the lightest substance consistent
with strength and a good surface, for reasons of postage costs.
Generally produced in white, off white or a pale blue for stationery
purposes, usually below 40g/m2. Manifolds and lightweight bonds
are also often known as airmail papers.
A term commonly, but incorrectly, applied in the paper industry
to various qualities of aluminium sulphate.
A characteristic low degree of surface finish which typifies
certain commercial descriptions of paper such as Antique Wove,
Antique Laid etc.
PAPER Paper containing added substances which give
it the property of protecting the surfaces of ferrous metals
SPRAY A device used on the delivery end of the printing
machine to prevent set-off by projecting a fine spray, of liquid
or powder, at the sheet.
Adsorbable Organic Halogens. AOX expresses the amount of organic
chlorine compounds in effluent produced as the chlorine chemicals
react with the residual lignin (q.v.) in the bleaching of pulp.
A safe AOX limit is easier to achieve using chlorine dioxide
than with chlorine.
DENSITY The quotient of the grammage of a paper and
its thickness in micrometres.
This is a generic term given to woodfree coated papers, which
has traditionally referred to papers in the upper quality bracket
and which have a high polished surface. Today the term is less
used because of the introduction of more categories in the sector.
However, Real Art is still used for those woodfree
coated papers, gloss or matt, which are considered to be of
the very highest quality.
The amount of residue when a sample of paper is burned under
controlled conditions so that all ignitable matter is removed.
The ash derives from the mineral loading in the paper.
To print on the reverse side of a printed sheet.
The liquid which passes through the forming
surface when stock is deposited upon it. It is essentially water,
but generally contains dissolved matter or suspended matter
such as fines, filler, etc. Backwater is normally recirculated
within the paper making process, or sent to treatment plant
for the recovery of materials in suspension.
Pulp obtained by chemical means from bagasse,
the residue after extracting the juice from sugar cane.
BAMBOO PULP Pulp
obtained by chemical means from the stems of bamboo, a type
of grass common to Asiatic countries.
BANKS AND BONDS
A range of printing and writing
papers, the better qualities of which were at one time made
largely from rags. The heavier substance papers, above a substance
of about 60g/m2, are often used for correspondence and letterheads,
and are known as bonds, while the lighter weights called banks
used largely for file copy papers have less use today with the
introduction of the automated office.
A major source of energy for pulp mills. The raw timber is debarked
before chipping, the bark being recovered and burnt at a steam
Paper intended to be converted, e.g. by a coating process or
by impregnation. Term sometimes used also for paper to which
a layer of other material (aluminium, plastics, etc.) is bonded.
Also called Body Paper or Rawstock.
The mechanical treatment of fibrous materials in a beater or
refiner to modify certain of their characteristics in order
to give them the properties necessary for the manufacture of
a desired quality of paper.
Very thin printing papers. Originally made specifically for
bibles and prayer books, this grade of paper is also used for
other commercial purposes, such as dictionaries, where many
pages are required with an overall low volume. Bible paper is
also known as India paper.
The adhesive used to stick the layers of
coating together and to the paper or board surface. The most
frequently used binder is starch, but synthetic binders are
also used to give improved performance.
A substance which will decompose as the
result of action by bacteria and other living organisms.
OXYGEN DEMAND (BOD)
This expresses the amount of dissolved oxygen
consumed by micro-organisms as they decompose organic material
in polluted or natural water. The higher the amount of decomposable
material, the higher the BOD value.
WASTE WATER TREATMENT
A variety of methods are used by pulp and
paper mills for purifying their waste water (such as the activated
sludge method) in which natural micro-organisms decompose the
organic substances. The organisms constitute a nutrient cycle
consisting of bacteria, protozoa and higher organisms. The method
reduces the biological oxygen demand by over 95% and removes
about 50% of the organic compounds from effluent, organic chlorine
Defect associated with calendered paper
occurring as unintended local areas of apparently darker or
greyer colour due, for example, to the paper being too damp
when passed through the calender.
Paper coated by a process in which the freshly applied wet coating
is smoothed and the excess removed by a thin, flexible metal
blade which bears on the coated surface.
The cylinder on a printing machine covered with a rubber (or
similar) blanket, which conveys the image from the plate to
A printing machine in which the blanket cylinders act as opposing
impression cylinders, so allowing both sides of the web or sheet
to be printed simultaneously.
The part of a printed image beyond the area
to which the finished print will be cut.
This term describes a packaging system which is a combination
of board and plastics. The product is sealed to the board by
a transparent plastics film. This system is often used for small
products of difficult shapes and sizes.
Highly absorbent papers which can be watermarked,
white or in colours. With the advent of the ball-point pen,
the original use where hand writing ink is absorbed has greatly
Heavy weight paper. The line of demarcation
between paper and board is indeterminate. For many purposes
it is taken as 220 or 225g/m2 but many products below these
levels are described, commercially, as board.
The biological oxygen demand (q.v) of a
waste water sample, measured over seven days exposure
See Banks and Bonds
The calculated limiting length of a strip of paper of any uniform
width, beyond which, if such a strip were suspended by one end,
it would break by its own mass.
Paper and pieces of paper arising at any
point in the mill which are suitable only for repulping, e.g.
wet paper removed from the paper machine or dry paper arising
as trimmings etc., faulty paper etc.
A method of coating a web of paper in which the applied coating
slip is distributed and smoothed by means of brushes, some stationary
and some oscillating across the web.
PACKED ON PALLETS BPOP
A method of packing paper in which the sheets
are not wrapped in parcels but stacked on the pallet, tabbed
at the required intervals to indicate quantity and over-wrapped.
A mechanical paper made to a specific caliper as opposed to
a fixed grammage. Typical calipers are 102 and 127 microns.
This type of paper, used mainly for mass market paperback books,
also has several uses when converted, such as cash register
Paper which appears to be thick in relation to its grammage.
The quotient of the bursting strength of a paper and its oven-dry
grammage as defined in the standard method of test.
The quotient of the bursting strength of a paper and its grammage
in the conditioned state as defined in the standard method of
The pressure necessary to rupture a sample of paper fixed horizontally
between two ring clamps.
Paper which has been smoothed and polished
between sets of rollers called a calender; this process is usually
done at the dry end of a paper making machine.
A thin tissue paper coated on one side with
colouring agent or carbon black which is transferred to a sheet
of paper underneath when pressure in applied.
This consists of two sheets of paper; the underside of the top
sheet is coated with colourless dye in minute gelatine capsules;
the underneath sheet is coated with a reactive chemical which
turns blue or black when mixed with the colourless dye; pressure
from a pen or typewriter on the top sheet causes the gelatine
capsules to break, the dye and chemical mix and the blue or
black copy appears on the bottom sheet.
A container usually made of relatively thin
carton or folding board, but sometimes partially or totally
of plastic; it is delivered by the carton manufacturer to the
user in either flat or collapsed form.
Slightly rough coated or uncoated printing
surfaced paper used for a variety of graphic purposes such as
envelopes. The name comes from the original use for the paper
which was for forming the tube section of a shotgun shell.
Large boxes made of board which are used
as containers for packages; cases are mainly used for transit
and storage purposes.
A method of drying coated paper by contact
of the freshly coated surface with a highly polished chromium
plated heated metal surface.
A cręped web or sheet of open formation
made of cellulose fibres and comprising one or more plies of
Spaced lines at right angles to laid lines
occurring as a watermark in paper.
CHAIN WELTS (CHAIN
Defect in reels due to variations in thickness
across the width, resulting in the slack areas assuming a chain-like
pattern around the periphery.
The ready removal, in the form of a powder,
of an insufficiently bound layer of pigment on the paper surface
resulting from the absorption into the paper of too high a proportion
of the vehicle of an ink.
This measures the oxygen demand caused by all impurities in
the water when oxidising a sample with a strong oxidant. (c.f.
Natural mineral, consisting essentially
of hydrated silicate of alumina, used as a filler or as a component
in a coating slip.
A cheap board grade usually manufactured
from the lower grades of wastepaper.
A term used to describe both papers and
boards used for subsequent brush coating. The various qualities
are determined both by the actual grade of base material used
and the quality of the coating, which may be gummed. Coating
may be applied to one or both sides, depending on end use.
COATED PAPER OR
Material coated on one or both sides with a mixture of china
clay, latex and other loadings to fill up surface pits and improve
the printing surface. The process can be accomplished either
on-line on the paper making machine or away from the paper making
machine as a separate operation. There are a variety of coating
methods, these include: roll coating, blade coating, air-knife
coating and brush coating, or combinations of these types. A
very high quality form of off-machine coating is cast coating.
A layer of minerals applied to one or both
sides of paper or board to improve brightness, gloss and printability;
the mineral most often used is china clay, hydrated aluminium
silicate, but calcium carbonate and titanium dioxide are also
used; the coating is held together and stuck to the paper by
Local deformation of a sheet of paper due
to unequal shrinkage giving it a slightly crumpled appearance.
See Chemical Oxygen Demand
A planographic printing process capable
of producing high fidelity continuous tone colour reproductions,
i.e. no screen is used in producing the negatives from which
the plates are prepared.
Paper which has been treated in the mill
by exposure to hot, moist air to increase the moisture content
of the paper to what is considered to be an optimum level for
flatness and stability.
These boards are made to provide a variety
of product containers and are made from waste materials. They
may, however, be lined with bleached or unbleached kraft, or
other papers, depending on end use. Some of these boards may
also be treated with plastics to provide special characteristics.
grade widely used on modern high-speed accounting and similar
machines. The paper is supplied in reel form and along with
the printing process many finishing techniques can also be used,
such as perforation and special folds. A particular use is for
invoices, statements and similar documents, when it is normally
An image in which tonal gradation is produced
by changes in density.
Unsuitable material found in wastepaper
which must be removed from the pulp before making it into paper,
e.g. paperclips, string, plastics.
A firm that specialises in converting reels
and sheets of paper and board into packaging or finished goods
for sale to the
Treatment of fibrous raw material by heat
in the presence of water, usually with added chemicals.
grade of good quality, used for copying correspondence and documents.
May be glazed or unglazed. Most copier papers are laser compatible
and special grades are made for colour copying.
Board consisting of one or more sheets of
fluted paper stuck to a flat sheet of paper or between several
sheets. The following are the main classifications:
(a) Single face
corrugated fibreboard. Board consisting of one sheet of fluted
paper stuck to one sheet of facing.
(b) Single wall
corrugated fibreboard (also known as double faced). Board
consisting of one sheet of fluted paper interposed between
and stuck to two facings.
(c) Double wall
corrugated fibreboard (also known as double-double faced).
Board consisting of two sheets of fluted paper interposed
between and stuck to three facings.
(d) Triple wall
corrugated fibreboard. Board consisting of three sheets of
fluted paper interposed between and stuck to four facings.
That section of the wet end of the paper
or board machine at which the wet web leaves the vat machine
cylinder or Fourdrinier wire part or other forming surface.
Operation of crinkling paper from a roll
or cylinder in order to increase its stretch and softness. This
process may be carried out on or off the paper making machine.
Two types are recognised:
An on-machine operation carried out
on a dried web.
On or off-machine operation carried
out on a wet or partially dried web.
The direction in the plane of the sheet,
at right angles to the machine direction (q.v), in a sheet or
web of paper; the set expansion coefficient of paper is about
three times as much in the cross section as in the machine direction.
See Thermo Mechanical Pulp.
Operation of slitting and cutting watermarked
paper without regard to where the design falls in each sheet.
The design(s) may fall in different places in successive sheets
and some may be cut.
CUTTING TO REGISTER
Operation of slitting and cutting watermarked
paper so that the design falls approximately in a given position
in each sheet.
The process of applying water to the lithographic
plate on a litho printing machine. Also the application of moisture
to paper in preparation for a subsequent process, e.g. supercalendering.
The roller on a printing machine which applies
the moisture directly to the printing plate.
on the wet end of a paper making machine which is covered with
a woven wire and carries a design to form a watermark in wet
See Machine Deckle
See Machine Fill
The removal of printing ink and mechanical
impurities by flotation and/or washing pulped wastepaper before
it is recycled.
Ability of a paper to retain its dimensions
and its shape (a) despite changes in its moisture content under
the influence of, for example, variations of the surrounding
atmosphere, or (b) despite variations of the physical and mechanical
stresses during printing and converting operations or use.
Highly purified chemical pulp intended primarily
for conversion into chemical derivatives of cellulose.
A blade-like device which rests on the uprunning
surface of a roll in order to keep it clean by removing any
foreign matter adhering to the roll.
The appearance on the printed sheet, locally,
of two non-coincidental images obtained at one impression.
Substances, generally metallic compounds,
added to an ink to increase the rate of drying by catalytic
The part of a paper making machine where
the paper passes through steam-heated drying cylinders.
A method of printing, as in the offset lithographic
method, but from a relief plate, and without the use of fountain
The trough on a printing machine, usually
including an adjustable blade, which contains the supply of
ink and by means of which the ink is presented to the duct roller.
The cylinder in the duct of a printing machine
which, in conjunction with the adjustable knife blade, regulates
the amount of ink applied to the feed roller.
An unprinted representation of the text
pages of a book made by suitably folding and collating sheets
of the intended quality and grammage of paper so that an idea
may be formed of the general appearance and thickness of the
The operation of converting a web of paper
into sheets on a cutting machine equipped with two cross-cut
knives so that two different lengths of sheet can be cut simultaneously.
A common definition for pulp bleached without using elemental
chlorine. Originally any of the bleaching techniques for chemical
pulp, when no molecular (elemental) chlorine is used.
Device comprising two jets of water which
are adjustable across the making machine and which divide the
wet web on the wire lengthwise so that the edges may be removed,
generally at the couch. In this way they control the width of
the web going forward from the wire part and give it comparatively
Paper on which a raised and/or depressed
design has been produced by pressure, generally from an engraved
or otherwise patterned roll or plate.
Dispersion of water into the ink during
printing. An excess of this may cause printing difficulties.
Paper coated by any suitable coating process with plastics or
resins applied in the form of an emulsion.
Sometimes known as internal sizing. The
addition to the paper making stock of chemicals which ultimately
confer on the paper the property of resisting penetration by
aqueous liquids, e.g. writing ink.
The moisture content of a paper that has reached a balance with
the atmosphere surrounding it, i.e. in a condition in which
it will neither give up nor absorb moisture.
A grass naturally occurring in North Africa
which, when pulped, produces a bulky fibre for making good quality
paper; it was once a popular paper making fibre.
A method of coating a web of paper with
resins, plastics or similar hot-melt compounds. The coating
is applied through an extruder die positioned immediately above
the nip between a supporting roll and a chill roll.
The surface on a printing machine over which
the stock is conveyed to the lays.
Imprint left on the paper by one or more
of the felts used in making the paper. The mark may be wanted
or unwanted and special effects can be introduced in this way.
Freeing of the fibrils by partial rupture
of the fibres when submitted to an appropriate treatment, e.g.
beating or refining.
A material such as china clay or calcium
carbonate which is added to make paper smoother and increase
The addition of components of the furnish
of a paper to pulping or slushing equipment in a paper mill.
The spreading of the printed image on a sheet to the point where
the small unprinted spaces are obliterated.
Small fragments of fibres produced, for
example, in the course of beating or refining.
The surface characteristics imparted to
paper by mechanical means.
Paper which has been given a treatment designed to give it a
certain degree of non-flammability and/or of incombustibility.
A container for stock situated immediately
before the forming part of a paper or board making machine,
capable of supplying stock in the required volume and with the
required distribution characteristics to the forming surface.
Also known as the breast box or head box.
A dyestuff which is capable of converting
u/v light into the visible spectrum and improving the brightness
of the paper in which it is incorporated. Sometimes known as
optical bleaching agent (OBA).
Static bar-like devices situated below the
forming wire of a paper making machine to assist drainage of
water from the stock.
Although boxboards can vary in quality from
grey board (q.v) to high-class board made from virgin fibre,
the term is usually taken to mean white lined boards. They are
made on multi-layer machines, and the outer layers may be of
a different furnish to the centre layer.
The manner in which the fibres are disposed
in the sheet as determined by the look-through.
The roller on a printing machine which initiates
the supply of moisture to the damping system.
Water, with additives, for application to
the lithographic plate on a printing machine.
A paper making machine that forms the paper
in a continuous sheet; it was named after the Fourdrinier brothers
who financed the first operational machine at the Frogmore Mill,
Hertfordshire, in 1803.
Stock that, when drained under gravity,
parts easily with the water of suspension.
A measure of the drainability of an aqueous
suspension of stock, determined and expressed as specified in
a standard method of test.
The ingredients or constituents of which
the paper is made. Fibrous furnish concerns only the types and
proportions of the fibres present. Total furnish includes loading
(a) An image
which appears as a lighter area on a subsequent print, due
to local blanket depressions from previous image areas.
(b) Marring of
a print by an image on it of work on the reverse side which
has interfered with its drying, so that differences in the
trapping of some colours or gloss variations are apparent.
Gloss can refer to the reflectivity of paper
itself or of the printed result on it. Gloss of paper is measured
by using a Gardner gloss meter, which measures reflected light
at an angle of 75°, and is expressed in Gardner gloss units
- the higher the number, the glossier the paper surface.
A term applied to the machine direction
of papers or boards, as opposed to the cross direction.
The term used to denote the weight of paper
or board; the measurement used is the weight of a single sheet
of one square metre, expressed as grammes per square metre (g/m2).
Paper which resists grease, or prevents
the fats found in some goods from soaking into it; the paper
is produced by prolonged beating in the pulp stage.
Immature paper which has not been conditioned
or had the opportunity to mature naturally.
A device on a printing machine for holding
the sheet during the printing or similar cycle.
The margin of paper along the gripper edge
of the sheet held by the grippers and which therefore cannot
The edge of the sheet presented to the gripper.
The edge of the plate which is fitted to the leading clamp of
Mechanical pulp made by grinding wood against
an abrasive surface, e.g. a stone.
The representation of tonal gradation by
an image composed of dots of varied sizes, the centres of which
A grid in which the lines and spaces are
of equal thickness and equidistant used in photographing an
original for plate or block making.
Pulp obtained from the wood of hardwood
trees by various processes. The fibres are generally shorter
than those of softwood pulp.
FLOW BOX An elevated tank or container equipped with an
overflow device which, when supplied with excess of a liquid
or fluid, can deliver same at a constant hydraulic head to a
A printing ink produced to dry by the application
of heat after printing.
HOT MELT COATING
A method of coating with a 100 per cent
solids compound of wax, resin of polymer, or mixtures thereof,
heated to a fluid state and applied to the substrate by, for
example, a roll, gravure or extrusion process with a subsequent
A method in which pulp is bleached in an alkaline environment
with hydrogen peroxide, sometimes using oxygen reinforcement.
The method considerably reduces the need for chlorine-containing
chemicals in the final bleaching of chemical pulps.
That cylinder of a printing machine which
supports one surface of the sheet or web while the other surface
receives its printed image from a co-operating blanket cylinder.
A defect, often associated with matt coated
papers, in which parts of a dried ink film are removed by pressure
or friction from another surface.
A mill which starts with logs or wood chips
and first produces wood pulp which it then processes to make
paper or board; there are only five integrated mills in Britain.
A machine for producing sheets of thick board by winding the
web formed on a Fourdrinier wire or cylinder mould(s) around
a making roll to form a sheet consisting of several layers.
When the thickness is sufficient the layers are cut, so forming
a sheet which is removed from the machine for drying and any
The addition of materials to the stock,
generally in order to increase the resistance of the finished
paper to the penetration and spreading of aqueous liquids, e.g.
writing ink. Frequently described as engine sizing.
High-quality board made in white or colours
with a bright, clear appearance, particularly used for visiting
cards and similar high-class printed work. Original Ivory Board
was and still is made in Holland, although the grade is made
in many countries.
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.
Chemical wood pulp produced by digesting
the wood by the sulphate process. Originally a strong, unbleached
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.
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.
A continuous watermark consisting of very
close parallel lines, generally associated with spaced lines
(chain lines) at right angles to these.
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.
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.
A substance in wood which binds its fibres
together and reinforces its structure. Lignin is removed in
the manufacture of chemical pulp.
A planographic printing process in which
the non-image areas of the printing plate are made hydrophillic
and the image areas are made hydrophobic.
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.
See Short Grain
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.
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.
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.
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
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.
Paper which has been made reasonably smooth by means of calender
stacks at the end of the paper making machine.
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.
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.
See Airmail Paper
The greatest width of usable paper it is possible to make on
a given paper making machine, i.e. the full width less the necessary
trim to give clean edges. It is not possible to specify sizes
which, in aggregate, exceed this width.
Paper, the furnish of which contains a substantial
proportion of mechanical wood pulp.
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.
Pulp produced from wood solely by mechanical means such as grinding
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
rubber 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-cręping
is the Clupak process.
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 board situated between
the two external furnish layers, or between the underliners,
or between an underliner and an external furnish layer.
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.
The appearance of a printed image out of
its correct position.
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.
A machine in which a number of plies of paper can be combined
together in the wet state to produce thick cardboard.
Northern Bleached Hardwood Kraft. An important
variety of market pulp, produced chiefly from birch trees, it
is brighter than NBSK but not as strong.
Northern Bleached Softwood Kraft. One of
the chief varieties of market pulp, produced mainly from spruce
trees from Scandinavia, Canada and north-eastern USA. It consists
of longer (hence stronger) fibres than NBHK.
Carbon Required. This expression, which was introduced by the
National Cash Register company (which formerly owned the patents),
has now been superseded by the term Carbonless (q.v.).
The relatively low grade paper intended
for the printing of newspapers; it is mainly produced from mechanical
softwood pulp and recycled fibres.
Character Recognition Paper) Similar to MICR Paper (q.v.), a
high-quality bond paper of good surface and dimensional stability
for printing with characters for computer recognition.
Base paper to which a mineral coating has been applied on a
coating machine separate from the paper making machine.
A covering for a cylinder on a printing
machine for accepting the ink image and then transferring it
to the surface to be printed.
A method of printing in which the image
on the plate is transferred to the final substrate via an intermediate
The sidelay opposite to the operating side
of a printing machine.
Paper which has been coated with mineral matter by coating equipment
installed as an integral part of the paper making machine.
The process of covering the surface(s) of
a paper with one or more layers of coating slip or other materials
in fluid form, without recourse to a separate operation, the
necessary equipment being an integral part of the making machine.
The extent to which a paper is capable of
obscuring matter printed on the verso or on an underlying page
or other surface.
OUT TURN SHEET
A sheet of paper, taken during manufacture,
serving as a reference for the mill or client.
A method of reducing the lignin content
of pulp by introducing oxygen in an alkaline environment, thereby
reducing the need for other chemicals in final bleaching.
A method in which the lignin content of
pulp is reduced by means of ozone, a triatomic form of the element
oxygen. Used in combination with oxygen and hydrogen peroxide,
it can with present-day technology produce almost white pulp
without any chlorine chemicals. A toxic gas, it has to be removed
from the exhaust gases.
The paper and board used for wrapping or
An ancient writing material made from the
stem of the papyrus plant, an African reed. Although the word
paper is derived from papyrus, papyrus is not paper.
A sheet of writing material made from animal
skin, nowadays usually used to denote Vegetable Parchment (q.v),
or parchmentised papers. These have a high resistance to the
penetration of grease and atmospheric humidity. Used largely
for wrapping purposes, there are also grades of imitation parchments
which are less impervious. Similar to greaseproof paper (q.v.).
See also Vellum Paper.
This grade of board consists of one or more
layers, usually of pulp board, pasted together. It may be lined
both sides with paper of one type or another, depending on end
Printing both sides of the substrate at
the same pass through a printing machine.
Paper free from mechanical woodpulp or unbleached
fibre, generally neutral/alkaline sized and containing calcium
carbonate filler, made to controlled pH value and alkali reserve,
intended for the printing of books and similar works for posterity.
Any material present in waste paper that
is difficult to see or detect and which might be detrimental
to the paper being manufactured from the wastepaper or which
might either damage paper making equipment or render repulping
An acidic spot test reagent for paper that produces a red coloration
in contact with lignified fibre.
The process of composing text matter directly
onto a photographic or other light sensitive material.
A number on a logarithmic scale extending
from 0.3 to 14.5 which indicates the active acidity or alkalinity
of an aqueous liquid. Neutrality is represented by pH 7.07,
figures descending below this reading indicating increasing
amounts of acidity, and those above, alkalinity.
The rupture of the surface of a paper during
manufacture or during printing, which occurs when an external
tensile force applied to the surface is greater than the cohesion
of the paper.
Defect in reels, consisting of ridges running
around the circumference, due to moisture take-up by the surface
A type of board with a centre layer of gypsum
and outer layers of board, used in the building industry.
The cylinder in a printing unit to which
printing plates are fixed.
An MG grade with a quick drying surface
used for outdoor poster work. The rough underside lends itself
to rapid pasting.
This is a German word used to describe a
grade of board used for a variety of purposes, often industrial.
It is of a light weight, extra hard, rolled and friction glazed.
Paper coated with a self-adhesive material which in dry form
(solvent free) is permanently tacky at room temperature. A bond
with the receiving surface may be formed by the application
of pressure (e.g. by the finger or hand). A permanent adhesive
is characterised by relatively high ultimate adhesion and a
removable adhesive by low ultimate adhesion. Until the time
of application, the adhesive surface should be covered by a
suitable release coated paper.
A pre-production print, made for the purpose
of checking the accuracy of lay-out, type matter, tone and colour
Chemical pulp is made from a cellulose raw
material (usually wood) by treating it (cooking) with chemicals
to separate the cellulose fibres and dissolve the lignin, etc.,
which binds them together; it can be bleached or unbleached.
Mechanical pulp is made from wood by purely mechanical means,
i.e. grinding or refining of chips; lignin and other impurities
are not removed, and further processing (bleaching) is required
if a white sheet is required. Fibre obtained from wood by either
of the above methods is called primary, or virgin, fibre. Some
pulping processes involve both methods and also include heat
Also known as Printers Board, this
grade is made from a single web of pulp on a paper making machine,
and is produced in various substances. Used for index cards
and other general products, these boards may be white or coloured.
Any apparatus intended for slushing pulp
Paper made from stock containing a substantial
percentage of rag pulp. The minimum proportion of such pulp
required for a paper to be so designated cannot be specified
as it varies from country to country.
A unit of measurement for sheets of paper;
The final process in making paper; after
passing through the drying cylinders and, if appropriate, the
calender rollers, the newly-made paper is wound onto a jumbo
reel: this is the reel up stage.
A machine, usually equipped with discs or
with a cone and plug, intended for the treatment of fibrous
materials in an aqueous medium to give them some of the properties
needed for the manufacture of pulp or paper with the necessary
A set of fine line crosses or other suitable
devices added to the original artwork to provide reference points
for the subsequent registration of the colours of a set of printed
Any paper that has been strengthened mechanically
by the incorporation of other materials such as plastics, threads,
cloth or strips of metal.
Quotient of the amount of moisture in air
and the amount that would saturate it at the same temperature
and pressure, expressed as a percentage.
which has become available as a result of overmaking or side-runs
or because it is in some way less than perfect; perhaps non-standard
or slightly sub-standard. Although sold without a guarantee
the substance and size tolerances would be expected to conform
to industry standards. Often referred to as clearance paper.
Sometimes a material which has the same
appearance and purposes as paper is called paper.
Rice paper is an example, since it is not paper, but the sliced
and flattened pith of a plant which grows in Taiwan; it is used
by Chinese artists as a surface for painting.
Any method of coating a web of paper in
which the coating is applied directly to the paper by transfer
from an applicator roll which carries the coating slip upon
its surface. The applicator roll may rotate in the same direction
as the paper web or in the reverse direction (reverse roll coating).
Traces of printing ink which temporarily
adhere, during litho printing, to the non-image area of the
plate due to its inability to repel ink.
Paper which includes identification features
such as metallic strips and watermarks to assist in detecting
fraud and to prevent counterfeiting.
Used essentially for labelling purposes,
this grade has a self-adhesive coating on one side and a surface
suitable for printing on the other. The adhesive is protected
by a laminate which enables the sheet to be fed through printers
or printing machines, the laminate subsequently being stripped
when the label is applied.
Pulp obtained by partial removal from the
raw material of those non-cellulosic components that can be
removed by a direct chemical treatment, e.g. cooking: to resolve
the fibres, some subsequent mechanical treatment is necessary.
The unwanted transfer of printing ink from
a print to a facing surface.
Coarse fragments of fibrous materials present
in pulp or paper, resulting from incomplete resolution during
The fibres in a web of paper naturally take
up an alignment roughly parallel to the direction of travel
of the web on the paper making machine; this becomes the grain
direction. When cut, the papers grain direction may be
parallel either to the long edge of the finished sheet (when
it is called long grain) or the short edge (short grain). Papers
are normally stocked in long grain form, short grain being supplied
to special order. The grain direction affects the stiffness
in a particular dimension and must be taken into account when
planning a job which needs to be folded, as paper usually folds
easier with the grain.
The degree to which a printed film is visible
through paper due to the low opacity of the paper.
A datum point on a printing machine for
positioning correctly the side of the sheet in relation to the
Mechanism for moving
the sheet to this datum point.
(a) A narrow
reel removed from a web during processing, the width of which
is less than the size ordered, but is large enough to permit
its use for purposes other than re-pulping.
(b) An additional
part of an order placed in order to better utilise the maximum
trimmed machine width of the making machine.
This process can either be applied on the
surface of the sheet or in the sheet: in the first case starch
is applied to the surface to increase its strength and to resist
the penetration of oil-based inks (this process is carried out
at the size press, which is about two-thirds of the way down
the dry end); in the second case chemicals are added to the
stock at the pulping stage before the sheet is formed: this
is called internal or engine sizing and its purpose is to stop
penetration of water-based inks into the sheet.
Dividing a web of paper in the lengthwise
direction into two or more narrower webs.
The surface smoothness of paper is measured
by the Bendtsen smoothness test. The test measures the amount
of air escaping between an annular ring and the material surface,
and results are measured in ml/min. Papers having a value higher
than 50 are usually referred to as Matt, below 50 as Silk (sometimes
called Satin or Velvet).
A relatively new method of smoothing paper.
Soft calenders are more compact than other calenders and adopt
a system whereby the web is passed between steel and hard rubber
rolls. The method permits a wide variety of finishes between
gloss and matt and the retention of bulk.
Pulp obtained from the wood of coniferous
trees by various processes.
A board comprising a single furnish layer.
A board, which may be pasted or unpasted,
and often incorporating a lining of Kraft or other strong furnish,
intended and suitable for the manufacture of fibreboard packing
cases and drums.
Paper coated by any suitable coating process with resins or
plastics dissolved in volatile solvents which are subsequently
Joint in a web of paper in or approximately
in the cross direction, made either by an adhesive or an adhesive
(a) to obtain
a reel of the desired length or
(b) to permit,
for example in a converting machine, a continuous operation
between the end of one reel and the beginning of the next.
A method of coating a web of paper by means
of a vertical plate restraining a pond of viscous coating material,
for example resins, plastics or adhesives, which is drawn through
an adjustable gap between the plate and the paper by the forward
movement of the web over a horizontal support.
A type of calender, generally situated at
the end of the making machine, of which the rolls are of metal
The wet pulp before it is fed onto a paper
making machine, or during the paper making processes before
it becomes a sheet of paper; contains around 99% water and 1%
Collective term for all treatment necessary
for the preparation of the stock before it reaches the making
Paper making pulp obtained from cereal straws
by various processes.
The effect seen on the verso of the sheet
due to excess penetration of printing ink or vehicle into or
through the paper.
of paper or board, shown by scales, taken from a sample. The
weight is nowadays almost entirely defined by grammage per square
metre of a single sheet (g/m2).
Pulp obtained by cooking the raw material
with a mixture consisting of caustic soda, sodium sulphide and
possible other compounds, such as black liquor.
Pulp obtained by cooking the raw material
with a bisulphite liquor.
A surface finish on paper which may vary from relatively dull
but smooth to highly glazed, produced by passing dampened paper
through a supercalender stack. This is broadly similar to a
machine calender stack except that it is separate from the paper
making machine and some of the rolls are of compressed fibre.
Portable testing instrument designed for
insertion into a stack of paper to assess whether the moisture
content of the paper is in equilibrium with that of the surrounding
Paper produced by conventional means from
furnishes comprising substantially or wholly synthetic fibres.
resembling paper, made from synthetic filaments by other means,
e.g. spin bonding. Plastics material in sheet form, surface
treated to render it suitable for commercial graphic printing.
That property, governed by viscosity and
adhesion, which renders a film of printing ink sticky to the
Chlorine Free) Pulp bleached without any chlorine chemicals
The maximum tensile force that a test piece
of the paper will stand before it breaks under the conditions
defined in the standard method of test.
Mechanical pulp in which the wood chips are heat treated before
refining (commonly referred to as TMP). In some modern plants
a degree of chemical treatment is employed as well (chemi-thermo
mechanical pulp or CTMP).
The distance between one surface of a paper
and the other. Also known as caliper. It is measured in micrometres.
Another name for pasteboard, although coated
board can be included in this grade, which is used for tickets,
showcards or similar purposes. May be white or tinted.
Soft, lightweight paper, often creped, generally
between 17 and 30g/m2 in weight which is used for hygienic,
household and several other purposes.
The operation of surface sizing paper by
passing it through a bath of a suitable solution such as gelatine.
Paper or board made on a paper making machine
with a duplicated wire part. In this way two sheets are formed
and combined wireside to wireside so that the finished sheet
has two identical printing surfaces.
An unintended difference of varying degree
in surface texture or shade between the two faces of a paper
or board, which is inherent in the method of manufacture.
Paper produced by combining together two
webs or sheets of paper with bitumen, tar, or similar moisture/moisture
vapour resistant materials.
A description of towns and cities which
are the source of wastepaper as one of the raw materials used
for paper making.
A paper or board making machine comprising
one open ended cylinder, or more than one open ended cylinder
in series, covered with fine mesh wire, which revolves in a
vat of stock. Water draining through the wire leaves a mat of
fibres on its surface and the ultimate thickness of the product
may be determined by the number of cylinders used. The resultant
web is removed from the last cylinder and then passed through
conventional pressing and drying sections.
Waterleaf paper that has been modified by
the action of sulphuric acid. This treatment gives it a continuous
texture, increased surface hardness and a high degree of resistance
to penetration by organic liquids, generally and particularly
fats, oils and greases. The structure also confers on the paper
resistance to disintegration by water, even at boiling point.
Vellum paper - strong, tough and of high
class appearance - is made to imitate the fine smooth finish
of a parchment made from animal skin. Vellum paper is often
used for certificates.
Paper or board pulp fibre being used for
the first time (as opposed to recycled fibre). See also Pulp.
An expression used principally in the context
of papers for book printing to denote the theoretical thickness
in mm of 100 sheets (200pp) of the given paper in 100g/m2. It
thus gives an indication of the bulk of the paper.
A deliberate design or pattern in paper
made by a dandy roll as the stock passes through the wet end
processes; a watermark can be seen by holding the paper up to
The first stages of a paper making machine before the drying
process; at the wet end, stock is fed in and much of the high
percentage of water is eliminated by drainage, suction and press
rollers, leaving a web of paper which then passes to the drying
The superimposing of successive colours
while the printed colour is still wet, in one pass through the
Paper so treated as to decrease its loss
in strength upon wetting.
The ratio, expressed as a percentage, of
the value of a given strength property of a paper in the wet
state to that of the same paper in the dry state, measured according
to the standard method of test.
The face of a web or sheet of paper which was in contact with
the forming wire during manufacture.
Paper made wholly from chemical pulp and free from wood-based
impurities, such as lignin, which are present in mechanical
Printing one side of the sheet, then turning the sheet over,
retaining the same sidelay edges but reversing the front and
back edges, and using the same printing plate.
Printing on one side of the sheet, then turning the sheet over,
retaining the same front and sidelay edges of the sheet and
the same printing plate.
Paper first made as early as 1754 by forming it on a mould with
a cover made from woven wire cloth, hence wove paper;
the paper has no watermark and an even opacity; it is a type
of paper in common use today.