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paper
Paper is a thin, flat material produced by the compression
of fibres. The fibres used are usually natural and based upon cellulose.
The most common material is wood pulp from pulpwood (largely softwood)
trees such as spruces, but other vegetable fibre materials including
cotton, linen, and hemp may be used.
A stack of 500 sheets of paper is called a Ream. The edges of paper
sheets can act as very thin, fine-toothed saws, leading to paper
cuts.
Manufacture
Whether done by hand or with a Fourdrinier Machine, the paper making
process has four simple steps:
Preparation of the fibres
The material to be used for making paper is first converted into
pulp, a concentrated mixture of fibres suspended in liquid. As many
of these fibres are derived from natural sources, this process often
requires many stages of separation and washing. Once the fibres
have been extracted, they may also be bleached or dyed to alter
the appearance of the final product.
Forming into sheets
The pulp mixture is then further diluted with water resulting in
a very thin slurry. This dilute slurry is drained through a fine-mesh
moving screen to form a fibrous web. A watermark may be impressed
into the paper at this stage of the process. This moving web is
pressed and dried into a continuous sheet of paper.
In the case of the mould process, a quantity of the pulp is placed
into a form, with a wire-mesh base (or other draining device), so
that the fibres are left coated on the mesh and excess water can
drain away. At this time, pressure may be applied to remove more
water through a squeezing action. The paper may then be removed
from the mould, wet or dry, and go on to further processing.
Most mass-produced paper is made using a continuous (Fourdrinier)
process to form a reel or web. When dried, this continuous web may
be cut into rectangular sheets by slitting the web vertically and
then cutting it horizontally to the desired length. Standard sheet
sizes are prescribed by governing bodies such as the International
Organization for Standardization (ISO).
Drying
The paper may actually be dried several times during its manufacture.
Dry paper is much stronger than wet, so it is best to keep the paper
dry to prevent it breaking and stopping the production line (sometimes
the paper does break in which case it is converted back into pulp
and fed into the line).
Applications
Paper trimmerto write or print on: the piece of paper becomes a
document; this may be for keeping a record (or in the case of printing
from a computer or copying from another paper: an additional record)
and for communication; see also reading. Also a paper may represent
a value:
paper money
bank note
check
security
voucher
ticket
In such cases making a copy that can not easily be distinguished
from the original should be very difficult, to avoid abuse, see
counterfeit.
The paintings are the excellent portrayal of the events and scenes
that we see around us. The painters are the best cameras of the
world. They reproduce many different types of pictures. They even
draw imaginary pictures that do not exist in this world. We tend
to use both thinned oil paints and dense oil paints. Masterpieces
can be dyed more than once, but each time it may be different from
the existing paintings.
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