Paper is made by a simple, yet technical process.The steps include firstly gathering the 'raw' material, secondly cleaning the material, thirdly chipping (created into wood chips), fourthly digesting (soaked in chemicals), fifthly churned, sixthly setting of fibers, seventh screening, eight blotting, ninth squeezing, tenth drying, and eleventh ironing. The steps are further explained below...
Gathering the Raw
Material Paper can be made of almost any fibrous
material. The Arabs used to make it out of linen and flax
and rags, or out of various vegetable fibers. We still
use all of these things and many others -- hemp and jute,
cornstalk, straw, old rope, bamboo, and many others. But
the main thing we use is wood. At one time thousands of
square miles of trees had to be cut down in order to make
just a few hundred feet of paper, but modern plants
frequently use scraps left over from lumber mills and the
parts of trees that are too small to make into lumber, as
well as trees specially grown for the paper mill.
Cleaning the Raw
Material Whole trees must be cut into managable
lengths and then stripped of their bark before the
papermaking process can begin. The debarking is typically
done by a revolving drum in which projecting blades cut
away the bark and leave a fairly smooth log. The logs
must also be washed down to remove loose dirt and foreign
objects. Lumber mill scraps can usually skip the
debarking process but must still be cleaned before
proceeding to the next step.
Chipping Once
debarked and cleaned the logs/scraps are sent to a huge
machine that reduces them to uniformly-sized chips.
Digesting The
wood chips are dumped into a huge cylinder called a
"digester," in which they are soaked in a bath
of chemicals -- mainly bisulphite of lime -- and cooked
under pressure for about eight hours. All wood contains,
along with the cellulose that make paper, a great deal of
other material that will slowly decay; the digesting
process removes this other material, leaving just the
cellulose.
Beating and Churning The digested mixture is
passed to a machine that beats and churns it. The mixture
goes in with a consistency much like that of cottage
cheese and comes out as a smooth milky liquid similar to
that of thin latex paint.
"Setting" of
Fibers The mixture then goes into the Jordan
Engine, a huge revolving tank with revolving blades that
cut the wood fibers into even lengths. It is at this
stage that various "fillers" -- such as talc or
china clay -- and/or "sizing agents" are added.
These fillers and sizers are what give the finished paper
its specific color, strength, and fineness/roughness of
writing surface. The mixture is now ready to be turned
into what we recognize as paper.
Screening The now latex-consistency pulp mixture
passes through a strainer that takes out any remaining
lumps and is then sent to the machine which will turn
into paper. The pulp mixture runs as a filmy sheet or
"web" upon a fast-moving belt of fine
copper-wire mesh. The belt carries it along, letting the
water drip out of it and also drawing the water out by
suction; and it shakes the pulp a bit from side to side
to settle the fibers firmly. Toward the end of the trip
on the wire belt the sheet may pass under what is known
as a "dandy roll" where it receives a
watermark.
Blotting
From the "dandy roll" the pre-paper product
passes through a pair of felt rollers that "blot
up" much of the leftover water.
Squeezing The sheet then
passes through a series of steel rollers that squeeze
even more water out, as well as help stiffen the sheet.
Drying The final set of
drying rollers are heated from the inside and remove the
last traces of moisture.
Ironing The final stage
involves sending the long sheet through what is known as
a Calendar Stack. This stack of rollers "irons"
the sheet flat. The more rolls there are in the stack,
the smoother the paper becomes. The finished paper is
rolled up and the process is complete.
Works Cited:
"How We Make Paper." Richards Topical Encyclopedia. New York:The Richards Company, Inc., 1961. (volume IX, pages 273-280).
