THE PAPER

FUNDAMENTALS OF PRINT PRODUCTION

HISTORICAL BACKGROUND
Since time immemorial, man has sought and found various supports to anchor
thought, to preserve the memory of the events that interested him and, subsequently,
establish writing. These supports came from very diverse materials and origins,
among those we found: stones, baked clay tiles, metal or wooden sheets,
fabrics, animal skins and bones, plant leaves, slabs of marble, of granite,
etcetera. The inscriptions in these materials responded to needs of different and very
of varied nature. For example, commemorations of a ritual type, such as the ancient inscriptions
on the gravestones; others of a historical type, such as the Persian inscriptions near
Behistun, which recounts the triumphs of Darius; others of a religious nature, others of a...
artistic, etc.
The metals, among which there were sheets of bronze and lead, and in some cases
exceptional, thin sheets of gold were frequently used for transmission
of liturgical or legal texts. Fabrics were also used abundantly, as
be the linen, or the silk, that the Chinese have used since ancient times as material of
writing. On some occasions, it was painted on cloth, while on others, it was embroidered.
registrations, and in some cases they came to be remarkable complete stories represented
in these materials. A notable example of this is the Bayeux Tapestry, which dates back to the century
XI and narrates the expedition of William the Conqueror against England. It is a piece of linen.
approximately 70 meters long by 0.50 meters wide that comprises a
set of 58 embroidered scenes and explanatory legends. It is remarkable the similarity with a
infographic that we can distinguish in this piece. We can also mention this type of
stories on the buffalo hides designed by the Native Americans of North America, in which
narrate the Battle of Little Big Horn, in which General Custer died in 1876.
Animal bones were also used, such as sheep scapulae, plant leaves,
for example, of palm trees and others, the wood and its bark. The word 'book' (from
Latin liber) comes from here, as the word originally designated the film located
between the bark and the wood of the tree.

THE PROTOPAPERS
The papyrus
It was made from the epidermis of a plant similar to rush, called papyrus or charta.
Aegyptiaca or Cyperus papyrus, from the family Cyperaceae, which grows abundantly
on the shores of the Nile, in Sicily, and on the banks of the Rhône. Egypt was the great producer and
papyrus consumer, which constituted its writing material par excellence, but not only
they used it, but also the peoples of the East, of Greece, of Rome, and of Europe
Western between 3000 BC and the 5th century AD. The papyrus was characterized by its long leaves.
and of soft stems, and its boiled inner part was consumed as food.
As a writing support, it was relatively inexpensive and lightweight, but fragile and scant.
moisture resistant, which is why in Egypt, a dry country, is where the greatest has been found
number of papyrus specimens extracted from the excavations. Papyrology, which is the
a discipline that is dedicated to its study and deciphering has resulted in the acquisition
a lot of information on the subject, from historical documentation to
fragments of classical authors.
The preparation was carried out, according to Pliny the Elder, in this way: "They prepare the
leaves dividing the papyrus into very thin strips but as wide as possible. The best ones
they are in the center of the stem, and from there outwards they follow in decreasing order of quality.
All kinds of papyrus are made on a board moistened with water from the Nile; this
Cloudy liquid acts as glue. First, on this inclined table, it is placed
strips of the total length of the papyrus, trimmed at their ends, are then placed
transversely other bands, in the form of a grid. They are subjected to pressure, this produces
a leaf that dries in the sun. Then all the leaves are gathered, putting the best ones first
to put an end to the worst. The meeting of these sheets, never more than twenty, forms a
'hand'... The inequalities of the papyrus are smoothed with a tooth or a shell, but the characters
they are exposed to being erased, the polished sheet is shinier but does not absorb ink as well.
The parchment
Animal skins were also a medium for writing. Among the skins, especially
prepared for this end, we have the parchment. Pliny the Elder recounts that at one point,
The monarchs of Egypt prohibited the export of papyrus to prevent the development of the
library of the kings of Pergamum, who their intellectual rivals were. So, these
They searched for a material that would replace it and found the solution in lambskins.
The preparation technique reached levels so specialized and of such perfection in the city
from Pergamum that the product took the name of the city. The Romans called it charta.
Parchment, from which our word 'parchment' derives. The preparation was carried out
basically like this: 'the well-scraped hide was placed in lime water to strip it'
of the fatty substances; then it was dried and rubbed, without further tanning, with finely ground chalk.
powdered; finally, it was polished with pumice stone or another similar means.
The product obtained from the skin of a stillborn, called vellum, was the finest variety.
and appreciated. During the High Middle Ages, the use of papyrus gradually disappears. The
parchment replaces it and predominates almost until the end of the Middle Ages.

The paper
Silk has been known to be used for the production of pseudopapers since the year 300.
around 200 B.C., and the use of tissue and linen paper since 200 B.C., but
of poor quality for writing and therefore were mainly used for wrapping.
The invention of paper is attributed to Tsai Loun (or Ts’ai Lun), a palace official who
was in charge of the supplies of the emperor Ho Ti's royal household. In the year 105 A.D. in
response to the emperor's request to obtain new materials to write about them.
offered a blank sheet of paper. The request was due to the fact that China was at that time a
bureaucratic society that required abundant documents to keep its records for
written. Tsai Loun took care of obtaining the necessary patents and organizing the production
on a large scale. It was made by: “the disintegration of plant fibers and
rags with a heavy wooden mallet in a stone mortar. The shape in Chinese hand
it was made up of a wooden frame, in which a fine bamboo fabric was held
joined with silk threads. As a cohesive material to bind the fibers and provide impermeability.
necessary, an agar extract was used, a seaweed that was already being used in China for purposes
medicinal since ancient times
In this way, the foundations were laid for the manufacture of a lighter support.
easier to store and transport than wooden planks and of better quality for the
writing that the silk fabrics used then. Here it is essential to point out the role that the
Chinese characters or ideograms played a role in unification, as a large number of
towns (within China itself, but also as far as Korea and Japan) that had different
languages were able to understand what was written. At this time, paper begins to
to be used as a support for recording writing and the manufacturing methods arise from
Kozo paper (probably the strongest and most durable material of all used in the
handmade paper production, from very long and indestructible fibers) and from mulberry bark
The Chinese were jealous guardians of their invention for 500 years, but in the
Around the year 600, paper was also being made in Korea and Japan according to the ancient
tradition and were perfecting the system. In the year 700, the production of paper had
arrived in almost all of Central Asia.

EXPANSION
The expansion of paper was due to the Arabs, who, due to an armed conflict, arrived at
the borders of China and took prisoners, among whom were experts in the
formula to produce paper. They had to, in exchange for their lives, reveal the way to
to produce it. Around the year 751, the first factory was established in Samarkand. In its
production used the abundant hemp and flax from the area to obtain a paper of
smooth and fibrous appearance. A second factory was later established in Baghdad in the year 795.
also with Chinese paper manufacturers. The Arabs are credited, among others, with the innovation
to introduce colors, the standardization of measurements, a method for aging paper and the
introduction of wires into the molds. Then, familiarized with the production of paper
they established mills in Baghdad, Damascus, Cairo, and later, in Morocco,
Spain and Sicily. Thus, in their expansion during the 12th century, the Arabs brought the technique of
paper production in North Africa and Spain. In this way, paper enters Europe,
almost certainly along the road to the city of Córdoba, where it is inferred that it was founded
first workshop (around the year 1036) given the conditions: presence of a large river,
abundance of rags and starch, and the fact that at this time, the city of Spain was living
a cultural splendor and was the center of teachings in medicine and mathematics.
The first workshop for which there is documentation is the one established in the city of Játiva.
around the year 1150, whose production was dispatched to both the east and the west. The
the next place where we find the presence of paper is in Italy, where it arrived either by
the path of Spain or through the movements caused by the Crusades. In this country
we found in the town of Fabriano data on paper production in the year 1275
approximately. Even today, excellent handmade papers are still produced.
characteristics in this place. Small workshops quickly spread throughout the country.
dedicated to paper production. Fabriano stood out not only for its mill
paper-maker, but also by the use of mallets in production and by the innovation of
to make satin rag paper with an animal gelatin glue.
This novelty was very well received by the scribes, which made it even more accepted.
replacement of parchment with paper. This glossy surface allowed the pen to glide.
that scribes used with greater kindness and less effort than on other supports, the
that prevented it from tearing due to excess pressure. To Italian paper production
we also owe the introduction of the use of watermark, the first known is from the year
1282 and from this town as well.
We have to wait until the end of the 14th century to find paper mills in Europe.
Central, where later, thanks to the invention of the printing press, they enjoy a huge
expansion. Although it is known that paper mills existed in England and Holland since
the late 15th and 16th centuries, respectively, their great development was achieved in the centuries
XVII and XVIII, above all, the Dutch, due to the immigration of French papermakers, to
the technical advances and the influence of Japanese paper. The handcrafting of paper
Until the end of the 18th century, paper was made by hand; it was the so-called 'tub' paper and it was
I made it with cloth. The technique was basically as follows: after discarding their
folds and seams and classified by colors and textures, the rags were introduced into a
container with water to be crushed by the action of a set of hammers with
iron tips After being thoroughly washed, they were placed in a basement where the
putrefaction "digested" them. This putrefaction was later replaced by a cooking in a
alkaline medium, such as quicklime or caustic soda. This pulp was again crushed by the
action of other bats until achieving a perfect paste that was whitened with various
procedures; initially through natural oxygenation, which was later replaced by agents
chemicals, such as sodium hypochlorites and chlorides. Finally, the paste was placed in
a "tub", a type of basin in which generally through a steam current, it
it maintained a smooth and uniform constant temperature.
The actual manufacturing involved extracting the paste from the vat using
"form", a frame made of hardwood equipped with a sieve or screen, generally made of
a fabric of very compact wire threads. The worker immersed the shape in the tub and it
It was filled with dough. The water drained instantly through the mesh.
small horizontal swaying movement helped to drain the water and at the same time generated the
binding of the fabric fibers contained in the paste. The shape was then poured over a
felt sheet or 'sayal'. In this way, the paper, still a fragile paste, was spread out and
flattened and was covered with a second sayal. Successively, they were interleaved and were
it formed a stack of paper that was then pressed to extract the maximum amount of
possible water.
After extracting the fibers, the stack was subjected to a new pressing, and then it was left
to dry completely. This procedure underwent its first modification when it
they replaced the crushing hammers with cylinders lined with cutting blades that rotate
constantly produced a faster and more efficient grinding than that obtained by the work of
the decks. Then came the invention of the continuous paper-making machine. By
Lastly, the cloth was abandoned as raw material and was replaced by the paste of
wood.

THE PRINTING PRESS AND THE DEMAND FOR PAPER

In 1440, Johann Gutenberg, from Mainz, invented the typographic art with which it is possible to
Compose texts of any length and obtain a large number of copies.
The printing press gave a true measure of the value and utility of paper since it brought together, besides
its graphic qualities, being abundant, cheap (costing a tenth of the price of parchment),
durable, transportable, and affordable for the enormous quantities required by printers.
A printing press needed three reams of paper daily (1,500 sheets); for this reason
there is a relationship so close between the manufacture of paper and printing, and it is not conceived
the prosperity of one without the other.
This is why, between the late 15th century and the mid-16th century, Europe was filled with windmills.
of paper. Until that moment, paper was of restricted use and alternated with parchment.
Because books could be published in large print runs, there was a greater thirst for knowledge, more
men who learned to read and write, and within a few decades all spiritual life
and cultural achieved a total resurgence. Due to the increasing consumption of paper, the acquisition
of raw materials, which was almost exclusively made of old rags, began to constitute a serious
problem, and a huge imbalance was created between supply and demand. There are reports of
all countries about ongoing conflicts between paper merchants and rag collectors. Many sovereigns
export prohibitions were declared to protect their industry.
The increase in the use of paper during the 17th and 18th centuries led to a shortage of fabrics and
rags, the only satisfactory raw materials that European papermakers knew; they tried
introduce various substitutes, but none produced good results. It was also attempted to reduce
the cost of paper through a machine that will replace the manufacturing process
manual.
Closer and of better quality each time
It was a Frenchman, Nicholas Louis Robert, an employee at the Didot workshop in France, who, in 1798,
he built an effective machine. With it, sheets of twelve to fifteen meters could be manufactured.
length. Robert could not perfect it and complete it, and it was developed in England by two
British, the brothers Henry and Sealy Fourdrinier, who were assisted by the English engineer
Bryan Donkin created the first of the machines marked with his surname in 1803.
In 1840, they introduced the wood grinding process to produce pulp, which allowed for
was able to manufacture paper from a raw material of lower cost. Ten years later, it
carried out the first chemical process to produce pulp, which also contributed to the
cost reduction. In 1844, Federic Gottlob Seller was the first to obtain, through a
mechanical process, wood pulp.
Around 1852, Meillier discovered cellulose and Tilghman patented the process by means of the
which cellulose was obtained from wood using calcium bisulfite. Since that date, all the
efforts converged towards the search for the improvement of machines and techniques,
renewal of materials and the reduction of production times.

INDUSTRIAL PRODUCTION OF PAPER

Paper is a porous structure obtained from the filtration and interweaving of
vegetable fibers of cellulose. With the addition of inert substances, such as fillers and
fillers, allows the formation into thin sheets of a material of low thickness, flexible,
lightweight and durable.
Plant fibers (which are the raw material in paper manufacturing) have cells that
They are surrounded and protected by solid fortified walls, with an interweaving of
resistant fibers, cellulose fibers. These are found in various plant species,
some of which are more suitable than others for paper production, due to their
different structure depending on the class or species.
This variation in structure (for example, fiber length, fiber width, its
wall thickness, its weight per unit length, etc.) will result, process of
transformation through, into different characteristics of the obtained pulps, such as
resistance, quality, printability, stability, etc.
The main sources of cellulosic material are:

Fruit fibers: cotton, silk floss, etc. They range in length from 5 to 30.
mm.

Liberian fibers: they are obtained from the outer bark ('liber') of the plants.
dicotyledons. Some are: mulberry, hemp, flax, etc. They vary in length between 5
and the 20 mm.

Leaf fibers: they are obtained from manual or mechanical scraping and their strands are oriented.
longitudinally. Some are: cassava (sisal), caroa, formium, etc. They vary in their length
between 2 and 15 mm.

• Grasses: bagasse, esparto, straw pulp. They range in length from 0.5 to 3 mm.

Tree fibers: the paper industry currently mainly uses wood from
various species as raw material for the production of pulp. Around the
95% of the pulp is obtained from wood, and only a very small portion is obtained
of the other usable subjects.

The chemical composition of wood is the determining factor for this, due to its
performance in the manufacturing process. Other plant materials different from wood, such as
like straw, grasses, etc., contain less cellulose and, therefore, have very
low yields. At the other end, cotton, which is almost pure cellulose, presents a
very high performance. As we mentioned earlier, plant fibers have
different characteristics due to their structure, depending on the class or species. A characteristic
the length of the fiber is important. This means that woods are classified according to it.
dimension in long fiber or short fiber. The longer fibers form a thicker layer.
coherent and, therefore, a more resistant paper. Among the short-fiber tree species
we can distinguish: oak, poplar, birch, beech, eucalyptus (species with a round crown and climate
tropical). Among the species of long fiber trees, we can distinguish: pine, fir, spruce,
araucaria, conifers in general (species with long crowns and cold climates).
Obviously, from the use of trees as raw material for manufacturing
paper, there was a marked deforestation, which has led to rationalization policies and
deforestation by some countries. It is estimated that the percentage obtained from
The recycling of the total paper in use would only reach 30% of the volume. Despite the policies
mentioned, this is still a problem today.

Some optical characteristics of paper

• Brightness: whiteness expressed as a level of approximation to the standard that is oxide of
magnesium, whose value is 100.
Opacity: degree of non-transparency of the paper, expressed as the percentage of light
transmitted.
Brightness: specular reflection of light on the paper surface expressed as a percentage
of reflected light.

Some physical characteristics of paper

• Grammage: it is the mass of the paper surface unit expressed in grams per square meter.
square, that is, the weight in grams of a square meter of paper (g/m2). This measurement is
very important since it determines the regulation of the paper pulp in the machine
function of weight in grams per square meter that will be given to the paper and why commerce
The cost of paper is calculated based on its price in pesos per kilogram.
Thickness or gauge: thickness of the paper (μm)
• Hand: specific volume. It is obtained by dividing the thickness by the grammage (cm3/g).

Some mechanical properties of paper

• Break resistance: breaking tension of a strip of standard width paper subjected to
a parallel extension.
Stiffness: resistance to bending.

Some printability features of paper

Print gloss: specular reflection of light on printed paper.
Ink rub resistance: the ability of printed paper to withstand abrasion.
Startup resistance: the ability of the stucco and the fibers not to separate during the
print.
Ink fixing: process of penetration of the varnishes, which leads to the immobilization of the
ink on the paper.
Drying of the ink: hardening of the ink film deposited on the paper.

Some commercial characteristics

Format: paper size expressed in centimeters. It is closely linked to the weight.
of the paper, since these variables affect the weight in kilograms of the ream.
Ream: 500 sheets.