Paper is a thin material produced by pressing together moist fibres of
cellulose pulp derived from wood, rags or grasses, and drying them
into flexible sheets. It is a versatile material with many uses,
including writing, printing, packaging, cleaning, and a number of
industrial and construction processes.
The pulp papermaking process is said to have been developed in China
during the early 2nd century CE, possibly as early as the year 105
CE, by the Han court eunuch Cai Lun, although the earliest
archaeological fragments of paper derive from the 2nd century BCE in
China. The modern pulp and paper industry is global, with China
leading its production and the United States right behind it.
2 Early sources of fibre
4.1 Chemical pulping
4.2 Mechanical pulping
4.3 De-inked pulp
4.5 Producing paper
6 Types, thickness and weight
8 Environmental impact
10 See also
13 Further reading
14 External links
Main article: History of paper
Hemp wrapping paper, China, circa 100 BC.
The oldest known archaeological fragments of the immediate precursor
to modern paper date to the 2nd century BCE in China. The pulp
paper-making process is ascribed to Cai Lun, a 2nd-century CE Han
In the 13th century, the knowledge and uses of paper spread from China
Middle East to medieval Europe, where the first water
powered paper mills were built. Because paper was introduced to the
West through the city of Baghdad, it was first called bagdatikos.
In the 19th century, industrialization greatly reduced the cost of
manufacturing paper. In 1844, the Canadian inventor Charles Fenerty
and the German F. G. Keller independently developed processes for
pulping wood fibres.
Early sources of fibre
Hemp based Paper.
Fibre was commonly used in
the production of paper from 200 BCE to the Late 1800's.
See also: wood pulp and deinking
Before the industrialisation of the paper production the most common
fibre source was recycled fibres from used textiles, called rags. The
rags were from hemp, linen and cotton. A process for removing
printing inks from recycled paper was invented by German jurist Justus
Claproth in 1774. Today this method is called deinking. It was not
until the introduction of wood pulp in 1843 that paper production was
not dependent on recycled materials from ragpickers.
Further information: Papyrus
The word "paper" is etymologically derived from
Latin papyrus, which
comes from the Greek πάπυρος (papuros), the word for the
Cyperus papyrus plant.
Papyrus is a thick, paper-like material
produced from the pith of the
Cyperus papyrus plant, which was used in
ancient Egypt and other Mediterranean cultures for writing before the
introduction of paper into the
Middle East and Europe. Although the
word paper is etymologically derived from papyrus, the two are
produced very differently and the development of the first is distinct
from the development of the second.
Papyrus is a lamination of natural
plant fibres, while paper is manufactured from fibres whose properties
have been changed by maceration.
Main article: Papermaking
Main articles: kraft process, sulfite process, and soda pulping
To make pulp from wood, a chemical pulping process separates lignin
from cellulose fibres. This is accomplished by dissolving lignin in a
cooking liquor, so that it may be washed from the cellulose; this
preserves the length of the cellulose fibres.
Paper made from chemical
pulps are also known as wood-free papers–not to be confused with
tree-free paper; this is because they do not contain lignin, which
deteriorates over time. The pulp can also be bleached to produce white
paper, but this consumes 5% of the fibres; chemical pulping processes
are not used to make paper made from cotton, which is already 90%
The microscopic structure of paper:
Micrograph of paper
autofluorescing under ultraviolet illumination. The individual fibres
in this sample are around 10 µm in diameter.
There are three main chemical pulping processes: the sulfite process
dates back to the 1840s and it was the dominant method extent before
the second world war. The kraft process, invented in the 1870s and
first used in the 1890s, is now the most commonly practiced strategy,
one of its advantages is the chemical reaction with lignin, that
produces heat, which can be used to run a generator. Most pulping
operations using the kraft process are net contributors to the
electricity grid or use the electricity to run an adjacent paper mill.
Another advantage is that this process recovers and reuses all
inorganic chemical reagents.
Soda pulping is another specialty process
used to pulp straws, bagasse and hardwoods with high silicate content.
There are two major mechanical pulps: thermomechanical pulp (TMP) and
groundwood pulp (GW). In the TMP process, wood is chipped and then fed
into steam heated refiners, where the chips are squeezed and converted
to fibres between two steel discs. In the groundwood process, debarked
logs are fed into grinders where they are pressed against rotating
stones to be made into fibres. Mechanical pulping does not remove the
lignin, so the yield is very high, >95%, however it causes the
paper thus produced to turn yellow and become brittle over time.
Mechanical pulps have rather short fibres, thus producing weak paper.
Although large amounts of electrical energy are required to produce
mechanical pulp, it costs less than the chemical kind.
Paper recycling processes can use either chemically or mechanically
produced pulp; by mixing it with water and applying mechanical action
the hydrogen bonds in the paper can be broken and fibres separated
again. Most recycled paper contains a proportion of virgin fibre for
the sake of quality; generally speaking, de-inked pulp is of the same
quality or lower than the collected paper it was made from.
There are three main classifications of recycled fibre:.
Mill broke or internal mill waste – This incorporates any
substandard or grade-change paper made within the paper mill itself,
which then goes back into the manufacturing system to be re-pulped
back into paper. Such out-of-specification paper is not sold and is
therefore often not classified as genuine reclaimed recycled fibre,
however most paper mills have been reusing their own waste fibre for
many years, long before recycling became popular.
Preconsumer waste – This is offcut and processing waste, such
as guillotine trims and envelope blank waste; it is generated outside
the paper mill and could potentially go to landfill, and is a genuine
recycled fibre source; it includes de-inked preconsumer (recycled
material that has been printed but did not reach its intended end use,
such as waste from printers and unsold publications).
Postconsumer waste – This is fibre from paper that has been
used for its intended end use and includes office waste, magazine
papers and newsprint. As the vast majority of this material has been
printed – either digitally or by more conventional means such
as lithography or rotogravure – it will either be recycled as
printed paper or go through a de-inking process first.
Recycled papers can be made from 100% recycled materials or blended
with virgin pulp, although they are (generally) not as strong nor as
bright as papers made from the latter.
Besides the fibres, pulps may contain fillers such as chalk or china
clay, which improve its characteristics for printing or
writing. Additives for sizing purposes may be mixed with it or
applied to the paper web later in the manufacturing process; the
purpose of such sizing is to establish the correct level of surface
absorbency to suit ink or paint.
Paper machine and papermaking
The pulp is fed to a paper machine where it is formed as a paper web
and the water is removed from it by pressing and drying.
Pressing the sheet removes the water by force; once the water is
forced from the sheet, a special kind of felt, which is not to be
confused with the traditional one, is used to collect the water;
whereas when making paper by hand, a blotter sheet is used instead.
Drying involves using air or heat to remove water from the paper
sheets. In the earliest days of paper making, this was done by hanging
the sheets like laundry; in more modern times, various forms of heated
drying mechanisms are used. On the paper machine, the most common is
the steam-heated can dryer. These can reach temperatures above
200 °F (93 °C) and are used in long sequences of more than
forty cans where the heat produced by these can easily dry the paper
to less than six percent moisture.
The paper may then undergo sizing to alter its physical properties for
use in various applications.
Paper at this point is uncoated.
Coated paper has a thin layer of
material such as calcium carbonate or china clay applied to one or
both sides in order to create a surface more suitable for
high-resolution halftone screens. (Uncoated papers are rarely suitable
for screens above 150 lpi.) Coated or uncoated papers may have their
surfaces polished by calendering. Coated papers are divided into
matte, semi-matte or silk, and gloss. Gloss papers give the highest
optical density in the printed image.
The paper is then fed onto reels if it is to be used on web printing
presses, or cut into sheets for other printing processes or other
purposes. The fibres in the paper basically run in the machine
direction. Sheets are usually cut "long-grain", i.e. with the grain
parallel to the longer dimension of the sheet. Continuous form paper
(or continuous stationery) is cut to width with holes punched at the
edges, and folded into stacks.
All paper produced by paper machines as the
Fourdrinier Machine are
wove paper, i.e. the wire mesh that transports the web leaves a
pattern that has the same density along the paper grain and across the
grain. Textured finishes, watermarks and wire patterns imitating
hand-made laid paper can be created by the use of appropriate rollers
in the later stages of the machine.
Wove paper does not exhibit "laidlines", which are small regular lines
left behind on paper when it was handmade in a mould made from rows of
metal wires or bamboo. Laidlines are very close together. They run
perpendicular to the "chainlines", which are further apart. Handmade
paper similarly exhibits "deckle edges", or rough and feathery
Paper can be produced with a wide variety of properties, depending on
its intended use.
For representing value: paper money, bank note, cheque, security (see
security paper), voucher and ticket
For storing information: book, notebook, graph paper, magazine,
newspaper, art, zine, letter
For personal use: diary, note to remind oneself, etc.; for temporary
personal use: scratch paper
For communication: between individuals and/or groups of people.
For packaging: corrugated box, paper bag, envelope, Packing &
Charta emporetica and wallpaper
For cleaning: toilet paper, handkerchiefs, paper towels, facial tissue
and cat litter
For construction: papier-mâché, origami, paper planes, quilling,
paper honeycomb, used as a core material in composite materials, paper
engineering, construction paper and paper clothing
For other uses: emery paper, sandpaper, blotting paper, litmus paper,
universal indicator paper, paper chromatography, electrical insulation
paper (see also dielectric and permittivity) and filter paper
It is estimated that paper-based storage solutions captured 0.33% of
the total in 1986 and only 0.007% in 2007, even though in absolute
terms, the world's capacity to store information on paper increased
from 8.7 to 19.4 petabytes. It is estimated that in 1986
paper-based postal letters represented less than 0.05% of the world's
telecommunication capacity, with sharply decreasing tendency after the
massive introduction of digital technologies.
Types, thickness and weight
Paper size, Grammage, and
Card and paper stock for crafts use comes in a wide variety of
textures and colors.
The thickness of paper is often measured by caliper, which is
typically given in thousandths of an inch in the United States and in
micrometers (µm) in the rest of the world.
Paper may be between
0.07 and 0.18 millimetres (0.0028 and 0.0071 in) thick.
Paper is often characterized by weight. In the United States, the
weight assigned to a paper is the weight of a ream, 500 sheets, of
varying "basic sizes", before the paper is cut into the size it is
sold to end customers. For example, a ream of 20 lb, 8.5 in
× 11 in (216 mm × 279 mm) paper weighs 5
pounds, because it has been cut from a larger sheet into four
pieces. In the United States, printing paper is generally
20 lb, 24 lb, or 32 lb at most.
Cover stock is
generally 68 lb, and 110 lb or more is considered card
In Europe, and other regions using the
ISO 216 paper sizing system,
the weight is expressed in grammes per square metre (g/m2 or usually
just g) of the paper.
Printing paper is generally between 60 g
and 120 g. Anything heavier than 160 g is considered card.
The weight of a ream therefore depends on the dimensions of the paper
and its thickness.
Most commercial paper sold in North America is cut to standard paper
sizes based on customary units and is defined by the length and width
of a sheet of paper.
ISO 216 system used in most other countries is based on the
surface area of a sheet of paper, not on a sheet's width and length.
It was first adopted in Germany in 1922 and generally spread as
nations adopted the metric system. The largest standard size paper is
A0 (A zero), measuring one square meter (approx. 1189 × 841 mm).
A1 is half the size of a sheet of A0 (i.e., 594 mm ×
841 mm), such that two sheets of A1 placed side by side are equal
to one sheet of A0. A2 is half the size of a sheet of A1, and so
forth. Common sizes used in the office and the home are A4 and A3 (A3
is the size of two A4 sheets).
The density of paper ranges from 250 kg/m3
(16 lb/cu ft) for tissue paper to 1,500 kg/m3
(94 lb/cu ft) for some speciality paper.
Printing paper is
about 800 kg/m3 (50 lb/cu ft).
Paper may be classified into seven categories:
Printing papers of wide variety.
Wrapping papers for the protection of goods and merchandise. This
includes wax and kraft papers.
Writing paper suitable for stationery requirements. This includes
ledger, bank, and bond paper.
Blotting papers containing little or no size.
Drawing papers usually with rough surfaces used by artists and
designers, including cartridge paper.
Handmade papers including most decorative papers, Ingres papers,
Japanese paper and tissues, all characterized by lack of grain
Specialty papers including cigarette paper, toilet tissue, and other
Some paper types include:
Coated paper: glossy and matte surface
Construction paper/sugar paper
Fish paper (vulcanized fibres for electrical insulation)
Oak tag paper
Much of the early paper made from wood pulp contained significant
amounts of alum, a variety of aluminium sulfate salts that is
Alum was added to paper to assist in sizing,
making it somewhat water resistant so that inks did not "run" or
spread uncontrollably. Early papermakers did not realize that the alum
they added liberally to cure almost every problem encountered in
making their product would eventually be detrimental. The
cellulose fibres that make up paper are hydrolyzed by acid, and the
presence of alum would eventually degrade the fibres until the paper
disintegrated in a process that has come to be known as "slow fire".
Documents written on rag paper were significantly more stable. The use
of non-acidic additives to make paper is becoming more prevalent, and
the stability of these papers is less of an issue.
Paper made from mechanical pulp contains significant amounts of
lignin, a major component in wood. In the presence of light and
oxygen, lignin reacts to give yellow materials, which is why
newsprint and other mechanical paper yellows with age.
Paper made from
bleached kraft or sulfite pulps does not contain significant amounts
of lignin and is therefore better suited for books, documents and
other applications where whiteness of the paper is essential.
Paper made from wood pulp is not necessarily less durable than a rag
paper. The aging behavior of a paper is determined by its manufacture,
not the original source of the fibers. Furthermore, tests
sponsored by the
Library of Congress
Library of Congress prove that all paper is at risk
of acid decay, because cellulose itself produces formic, acetic,
lactic and oxalic acids.
Mechanical pulping yields almost a tonne of pulp per tonne of dry wood
used, which is why mechanical pulps are sometimes referred to as "high
yield" pulps. With almost twice the yield as chemical pulping,
mechanical pulps is often cheaper. Mass-market paperback books and
newspapers tend to use mechanical papers.
Book publishers tend to use
acid-free paper, made from fully bleached chemical pulps for hardback
and trade paperback books.
Environmental impact of paper
Environmental impact of paper and Deforestation
The production and use of paper has a number of adverse effects on the
Worldwide consumption of paper has risen by 400% in the past 40
years[clarification needed] leading to increase in deforestation, with
35% of harvested trees being used for paper manufacture. Most paper
companies also plant trees to help regrow forests. Logging of old
growth forests accounts for less than 10% of wood pulp, but is one
of the most controversial issues.
Paper waste accounts for up to 40% of total waste produced in the
United States each year, which adds up to 71.6 million tons of
paper waste per year in the United States alone. The average
office worker in the US prints 31 pages every day. Americans also
use in the order of 16 billion paper cups per year.
Conventional bleaching of wood pulp using elemental chlorine produces
and releases into the environment large amounts of chlorinated organic
compounds, including chlorinated dioxins. Dioxins are recognized
as a persistent environmental pollutant, regulated internationally by
the Stockholm Convention on Persistent Organic Pollutants. Dioxins are
highly toxic, and health effects on humans include reproductive,
developmental, immune and hormonal problems. They are known to be
carcinogenic. Over 90% of human exposure is through food, primarily
meat, dairy, fish and shellfish, as dioxins accumulate in the food
chain in the fatty tissue of animals.
Some manufacturers have started using a new, significantly more
environmentally friendly alternative to expanded plastic packaging.
Made out of paper, and known commercially as PaperFoam, the new
packaging has mechanical properties very similar to those of some
expanded plastic packaging, but is biodegradable and can also be
recycled with ordinary paper.
With increasing environmental concerns about synthetic coatings (such
as PFOA) and the higher prices of hydrocarbon based petrochemicals,
there is a focus on zein (corn protein) as a coating for paper in high
grease applications such as popcorn bags.
Also, synthetics such as
Tyvek and Teslin have been introduced as
printing media as a more durable material than paper.
Continuous form paper (or "continuous stationery")
Environmental impact of paper
Graphene oxide paper
Paper and ink testing
Paper size, sizing
Papier "paper" in French or German
Parchment paper, a form of paper made to emulate the texture of
Roll hardness tester
^ Hogben, Lancelot. "Printing,
Paper and Playing Cards". Bennett, Paul
A. (ed.) Books and Printing: A Treasury for Typophiles. New York: The
World Publishing Company, 1951. pp. 15–31. p. 17. & Mann,
George. Print: A Manual for Librarians and Students Describing in
Detail the History, Methods, and Applications of
Printing and Paper
Making. London: Grafton & Co., 1952. p. 77
^ a b c Tsien 1985, p. 38
^ Burns 1996, pp. 417f.
^ Murray, Stuart A. P. The Library: An illustrated History. Skyhorse
Publishing, 2009, p. 57.
^ Burger, Peter (2007).
Charles Fenerty and his paper invention.
Toronto: Peter Burger. pp. 25–30. ISBN 9780978331818.
^ a b c Göttsching, Lothar; Gullichsen, Johan; Pakarinen, Heikki;
Paulapuro, Hannu; Yhdistys, Suomen Paperi-Insinöörien; Technical
Association of the Pulp and
Paper Industry (2000).
Recycling fiber and
deinking. Finland: Fapet Oy. pp. 12–14. ISBN 9525216071.
^ πάπυρος, Henry George Liddell, Robert Scott, A Greek-English
Lexicon, on Perseus
^ papyrus, on Oxford Dictionaries
Dictionary.com Unabridged. Random House. Retrieved 20
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^ Appropriate Technology. Intermediate Technology Publications.
^ Thorn, Ian; Au, Che On (2009-07-24). Applications of Wet-End Paper
Chemistry. Springer Science & Business Media.
^ "Document Doubles" in a virtual museum exhibition at Library and
^ a b "The World’s Technological Capacity to Store, Communicate, and
Compute Information", especially Supporting online material, Martin
Hilbert and Priscila López (2011), Science, 332(6025), 60–65; free
access to the article through here:
Paper Thickness Chart". Case Paper. Retrieved 2017-05-27.
^ Elert, Glenn. "Thickness of a Piece of Paper". The Physics Factbook.
^ McKenzie, Bruce G. (1989). The Hammerhill guide to desktop
publishing in business. Hammerhill. p. 144.
ISBN 9780961565114. OCLC 851074844.
Density of paper and paperboard". PaperOnWeb. Retrieved 31 October
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London: Thames and Hudson. OCLC 959020143.
^ Biermann, Christopher J/ (1993). Essentials of pulping and
papermaking. San Diego: Academic Press. ISBN 012097360X.
^ Clark, James d'A. (1985). Pulp Technology and Treatment for Paper
(2nd ed.). San Francisco: Miller Freeman Publications.
^ Fabbri, Claudia; Bietti, Massimo; Lanzalunga, Osvaldo. "Generation
and Reactivity of Ketyl Radicals with
Lignin Related Structures. On
the Importance of the Ketyl Pathway in the Photoyellowing of Lignin
Containing Pulps and Papers". J. Org. Chem. 2005 (70): 2720–2728.
^ Erhardt, D.; Tumosa, C. (2005). "Chemical Degradation of Cellulose
Paper over 500 years". Restaurator: International Journal for the
Preservation of Library and Archival Material. 26: 155.
^ "The Deterioration and Preservation of Paper: Some Essential Facts".
Library of Congress. Retrieved 7 January 2015. Research by the Library
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it ages, including formic, acetic, lactic, and oxalic acids
^ Martin, Sam (2004). "
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cross-reference to related application
Burns, Robert I. (1996). "
Paper comes to the West, 800–1400". In
Lindgren, Uta. Europäische Technik im Mittelalter. 800 bis 1400.
Tradition und Innovation (4th ed.). Berlin: Gebr. Mann Verlag.
pp. 413–422. ISBN 3-7861-1748-9.
Tsien, Tsuen-Hsuin (1985). Needham, Joseph, ed.
Paper and Printing.
Science and Civilisation in China, Chemistry and Chemical Technology.
V (part 1). Cambridge University Press.
"Document Doubles" in Detecting the Truth: Fakes, Forgeries and
Trickery, a virtual museum exhibition at Library and Archives Canada
Alexander Monro, The
Paper Trail: An Unexpected History of the World's
Greatest Invention, Allen Lane, 2014
Look up paper in Wiktionary, the free dictionary.
Wikimedia Commons has media related to Paper.
Technical Association of the Pulp and
Paper Industry (TAPPI) official
Paper at Encyclopædia Britannica
How is paper made? at The Straight Dope, 22 November 2005
Paper thickness cross reference guide
Thirteen-minute video on modern paper production system, from Sappi
Paper data storage media
Writing on papyrus (c. 3000 BCE)
Paper (105 CE)
Railroad/Transit Punch Photograph (1880s)
Punched card (1890)
Edge-notched card (1896)
Optical mark recognition
Optical character recognition (1929)
Units of paper quantity
Surface chemistry of paper
Manufacture and process
Bleaching of wood pulp
Environmental impact of paper
In the United States
List of paper mills
Decorative arts and handicrafts
Pressed flower craft
Die cutting (web)
Pressure sensitive adhesive
Country of origin
Cigarette warning label
EU energy label
Fair Packaging and Labeling Act
List of food labeling regulations
Nutrition facts label
Radio frequency identification
United Kingdom food labeling regulations
Automatic identification and data capture
Packaging and labeling
Track & Trace
Disposable food packaging
Modified atmosphere/modified humidity packaging
Bags and flexible containers
Corrugated box design
Flexible intermediate bulk container
Foam food container
Insulated shipping container
Intermediate bulk container
Self-heating food packaging
Linear low-density polyethylene
Liquid packaging board
Screw cap (wine)
Shock and vibration data logger
Temperature data logger
Time temperature indicator
Automatic identification and data capture
Blow fill seal
Die forming (plastics)
Electronic article surveillance
Track and trace
Verification and validation
Extended core stretch wrapper
Injection molding machine
Label printer applicator
Lineshaft roller conveyor
Material handling equipment
Mechanical brake stretch wrapper
Orbital stretch wrapper
Rotary wheel blow molding systems
Turntable stretch wrapper
Vertical form fill sealing machine
Glued laminated timber
Oriented strand board
Oriented structural straw board
Structural insulated panel
Ramial chipped wood
List of woods
Non-timber forest products
Palm-leaf manuscript (
Ola leaf (manuscript) (C. umbraculifera)
Birch bark manuscript
Wax tablet (wood)
Parabaik (S. asper)
Bamboo and wooden slips
Samut khoi kraing (paper usu.
Mulberry bark, metals, other)
Inherently impermanent material
Electronic visual display