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Paper-Making
And History
And History
How Is Paper Made?
The way we make paper today is not very
different from how the Chinese did it centuries ago - what differs is the
modern technology, which makes the process exponentially more efficient
Akash Peshin
Paper
is one of mankind’s most revolutionary inventions.
The
invention of paper finally put an end to the cumbersome task of carving on wood
or stone.
In
fact, the scope of information mankind could now limn was so enlarged that
paper wasn’t merely used to catalogue the details of trade, but of daily
events, to express feelings, wisdom, to write poems, to write stories we tell
ourselves to transcend or escape the mundanity of life or stories that nature
whispers to the ones who are keen to listen.
No
one is quite sure when the first sheet of paper was invented.
What
we do know is that it was invented some centuries ago in China, from where
China’s extraordinary trading network ensured that it was eventually exported
to other countries.
However,
how did the Chinese create it?
Trees
Surely,
everyone is aware that paper is made from trees, but you’d be surprised to know
that it is not made from their thin and soft leaves but rather their hard and
rugged logs!
A
logical question, of course, is how does a rigid, inflexible log bear something
as flexible and foldable as paper?
What
the Chinese first did was peel the bark off the logs. The large cylinders of
wood were then diced into chips as small as a few inches.
The
chips were dissolved and cooked in boiling water to form what is called a pulp.
The
cooking ensured that the wood was purged of its robust attributes. The pulp was
then left to dry in a rectangular vessel.
The
solution, like cement, would gradually and completely dry to assume the shape
of its container. What materialized was a thin, rectangular sheet of paper.
However,
the paper obtained, due to the primitivity of the prevalent technology, was
coarse and crude.
What’s
more, the paper would eventually turn yellow due to the presence of lignin, an
organic polymer that comprises the intricate structures of plant tissues.
As
technology flourished, we figured that we could produce papers of a more
refined quality.
However,
these papers would not only be smooth and velvety, but also wouldn’t be
blemished yellow with age.
The
Paper Mill
The
way we make paper today is not very different from how the Chinese did it
centuries ago.
What
differs is the modern technology, which makes the process exponentially more
efficient.
It
also allowed us to meticulously refine or regularize the inconsistencies in the
dried, flattened pulp.
We
also identified certain chemicals that, when dribbled into the cauldron, would
alter the paper’s texture in accordance with our desires.
Today,
the logs are first fed into a drum-shaped machine called a ‘debarker’ that, as
the name suggests, separates the bark from the logs.
The
wood is then diced into single-inch chips and cooked in a solution of acid to
separate the desirable plant fibers from the undesirable lignin, rendering the
solution pulpy and fibrous.
The
pulp is then described as wood-free because it only contains plant fibers.
This
pulp is cleaned and bleached with water to remove the acid and ensure that no
residual lignin survives.
The
treatment with water causes it to acquire the white color that is
characteristic of paper.
Apart
from the wood itself, water is the most important ingredient of the process. At
least 100L of water is required to make 1kg of paper.
However,
engineers have devised clever ways to ensure that very little water is wasted.
Almost
90% of the water is recycled by soaking or recirculating it on a mesh of pipes
throughout the long process.
In
fact, a majority of the wood chips used are actually the waste products of
sawmills!
Even
the chemicals used to bleach the pulp don’t include chlorine, but rather oxygen
and peroxide, to ensure that no harm is inflicted on the environment.
Next,
the pulp is passed through a series of adroitly placed blades to flatten the
fibers, which were entangled like earphones in your pocket.
Other
than eradicating inconsistencies, this process also gives the fibers
fibrillated ends, which facilitate fiber bonding with adjacent fibers, making
the paper much stronger.
Manufacturers
also add calcium carbonate to the pulp to enhance its density and opaqueness,
as well as starch or dyes to color it based on the buyer’s requirement, and
optical brighteners to further improve the paper’s appearance.
The
pulp is now ready to dry. To eliminate the water, the pulp is fed into the
paper machine, the heart of a paper mill.
The
paper machine is a conglomeration of different, smaller machines that
simultaneously perform a variety of chores.
Essentially,
the pulp is dried by making it gush through narrow spaces between rotating
wires and belts.
The
belts carry the water away, while the increased pressure and temperature ensure
that a sheet of paper rolls out from the other end.
To
remove any residual moisture, the paper is subjected to infrared radiation.
The
paper is then meticulously reviewed by experts who might send it for further
refining to eliminate any inconsistencies that might have been spared in the
previous processes.
The
rolls of paper produced can run up to 80km in length and 9m in width!
A
single roll can weigh as much as 120 tons! That is a lot of paper.
Finally,
the paper is divided into smaller lengths, which are loaded in cardboard boxes
to be sold in the market.
The
pulp is also treated with different chemicals to create different kinds of
paper, such as the craggy paper on which the content of a novel is printed, the
smooth paper that forms its cover, tissue papers, and let’s not forget the most
valued paper with which we buy every other paper: money!
So,
try not to take this most ubiquitous of materials for granted and appreciate
the prudence and stringent labor that goes into making it.
Akash Peshin is an Electronic Engineer from the University of
Mumbai, India and a science writer at ScienceABC. Enamored with science ever
since discovering a picture book about Saturn at the age of 7, he believes that
what fundamentally fuels this passion is his curiosity and appetite for wonder.
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