Teoria de Impresion Offset Basico

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Press Stage

Centro de Capacitación para la Industria Gráfica de

ACOACEIG de R.L.

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1.

1. PaperPaper

1.1.

1.1. Modern Paper manufacturing processModern Paper manufacturing process

Paper has been used for thousands of years as a tool for communication. At first, they used natural Paper has been used for thousands of years as a tool for communication. At first, they used natural fibers such as papyrus, cotton or other materials for its production. It was not until mid-19th fibers such as papyrus, cotton or other materials for its production. It was not until mid-19th century that began the widespread use of wood as raw material for paper.

century that began the widespread use of wood as raw material for paper.

Technically, there are over 25,000 types of plants with wood fibers, but conifers and deciduous Technically, there are over 25,000 types of plants with wood fibers, but conifers and deciduous trees, by its structure, are the most suitable for the manufacture of paper. Conifers have much trees, by its structure, are the most suitable for the manufacture of paper. Conifers have much longer fibers that are transient, and thus achieve much stronger paper. The most used coniferous longer fibers that are transient, and thus achieve much stronger paper. The most used coniferous three are the pine and the spruce. The eucalyptus tree is the most widely used of the deciduous three are the pine and the spruce. The eucalyptus tree is the most widely used of the deciduous family for wood free paper such as machine-coated papers.

family for wood free paper such as machine-coated papers.

Pulp manufacturing Pulp manufacturing

The pulp is the base from which paper is made. The pulp is the base from which paper is made. It'sIt's made from wood fiber, water and chemicals made from wood fiber, water and chemicals,, depending on their final use.

depending on their final use.

For the manufacture of pulp, trees are transported to For the manufacture of pulp, trees are transported to large processing plants. There, the first step is to large processing plants. There, the first step is to remove the bark from the trunks of trees. Once without remove the bark from the trunks of trees. Once without its bark, the wood must then be reduced to chips and its bark, the wood must then be reduced to chips and fibers, either through a mechanical or Chemicals fibers, either through a mechanical or Chemicals process.

process.

The mechanical process involves the application of The mechanical process involves the application of large amounts of water (98% of the material is now large amounts of water (98% of the material is now water), while the wood is ground against a rotating water), while the wood is ground against a rotating stone.

stone. The result iThe result is called s called mechanical pulp.mechanical pulp. The chemical process is much

The chemical process is much more complicated, havingmore complicated, having to cook on the wood under pressure with acid, which to cook on the wood under pressure with acid, which generates a cleaner pulp, which is called "wood-free generates a cleaner pulp, which is called "wood-free pulp”. In this section, we’ll focus only on the pulp”. In this section, we’ll focus only on the mechanical pulp.

mechanical pulp.

The resulting pulp is now brown and has to be bleached before it can be used to make paper. The resulting pulp is now brown and has to be bleached before it can be used to make paper. Modern techniques have replaced bleaching acid and chlorine, with an oxygen process, motivated by Modern techniques have replaced bleaching acid and chlorine, with an oxygen process, motivated by the environmental benefit of avoiding the use of toxic

the environmental benefit of avoiding the use of toxic chemicals.chemicals. Once the pulp has been bleached, it passes to

Once the pulp has been bleached, it passes to the paper mill for its the paper mill for its final conversion.final conversion.

Paper Composition Paper Composition

Upon entering the paper mill, the pulp is

Upon entering the paper mill, the pulp is refined (in the following figure, steps 1 through 4), refined (in the following figure, steps 1 through 4), passingpassing by huge rotating cylinders whose surface

by huge rotating cylinders whose surface is composed of several blades, which, moving in is composed of several blades, which, moving in or out,or out, generate different types of paper, depending on the desired structure.

generate different types of paper, depending on the desired structure. Already refined, the pulp is processed with c

Already refined, the pulp is processed with cellulose from an external source to obtain ellulose from an external source to obtain the final formthe final form of the paper.

of the paper.

Additives, such as calcium carbonate and clay are added to produce a more opaque paper and a Additives, such as calcium carbonate and clay are added to produce a more opaque paper and a more closed surface (Step 5). The calcium carbonate in particular helps the paper to be more more closed surface (Step 5). The calcium carbonate in particular helps the paper to be more resistant over the years. Components like these makes up to 30% of the final mass of the paper. In resistant over the years. Components like these makes up to 30% of the final mass of the paper. In addition, you can add other types

addition, you can add other types of components to the paper, such of components to the paper, such as dyes, optical brighteners,as dyes, optical brighteners, etc. Computers carefully regulate this whole process.

etc. Computers carefully regulate this whole process.

But undoubtedly, the most important material in the manufacture of paper is water. Up to a But undoubtedly, the most important material in the manufacture of paper is water. Up to a

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When the pulp is placed on the

When the pulp is placed on the bands of the machine (step 8 bands of the machine (step 8 and 9), these begin to vibrate to and 9), these begin to vibrate to createcreate a smooth surface, it's in this step that the chips and paper fibers are aligned and create the paper a smooth surface, it's in this step that the chips and paper fibers are aligned and create the paper grain direction.

grain direction.

It is during this step, going through the press that It is during this step, going through the press that the paper takes the form of a sheet, and it's the paper takes the form of a sheet, and it's

extracted most of the water (steps 12,13 and 15), extracted most of the water (steps 12,13 and 15), and we have what might

and we have what might be called paper.be called paper. However, for the paper to be used, it must be However, for the paper to be used, it must be prepared according to its next use. Among these prepared according to its next use. Among these preparations is the coating, (as in

preparations is the coating, (as in couche paper).couche paper). The coating of the paper (for example, with starch) The coating of the paper (for example, with starch) helps the paper to avoid absorbing dirt from the helps the paper to avoid absorbing dirt from the environment, and the printing looks clean and even environment, and the printing looks clean and even throughout the whole surface.

throughout the whole surface.

To a same type of paper you can apply different To a same type of paper you can apply different coating processes, as agents regulating its surface coating processes, as agents regulating its surface (natural like starches or synthetic such

(natural like starches or synthetic such as latex), bleach (calcium, carbonate, clays) and as latex), bleach (calcium, carbonate, clays) and dyes, asdyes, as well as special additives that each manufacturer

well as special additives that each manufacturer uses to distinguish its paper from uses to distinguish its paper from thethe competition.

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1.2

1.2 Paper propertiesPaper properties

•

• Basis WeightBasis Weight: the weight in grams of an area of one square meter.: the weight in grams of an area of one square meter. •

• BrightnessBrightness: the percentage of reflection at : the percentage of reflection at a wavelength standard. Is measured primarily on a wavelength standard. Is measured primarily on thethe white ideal. This property affects the c

white ideal. This property affects the contrast, tones, images, and the overall appearance of theontrast, tones, images, and the overall appearance of the printed product.

printed product. •

• GlossGloss: the percentage of light that is reflected from the surface, by firing a beam of light at a: the percentage of light that is reflected from the surface, by firing a beam of light at a certain angle.

certain angle. •

• RoughnessRoughness: is the difference between a perfectly : is the difference between a perfectly flat surface and the surface of flat surface and the surface of the paper underthe paper under review.

review. •

• Opacity Opacity : This is the amount of light that the paper lets (transparency) or not (opacity) go: This is the amount of light that the paper lets (transparency) or not (opacity) go through. Lower opacity lets more light trough than a high opacity.

through. Lower opacity lets more light trough than a high opacity. •

• RelativeRelative humidity humidity : the amount of water : the amount of water suspended in the air between the sheets of suspended in the air between the sheets of paper (andpaper (and not the water inside the paper). For

not the water inside the paper). For offset printing, the relative humidity should be between 50%offset printing, the relative humidity should be between 50% and 55%, and for office

and 55%, and for office paper, 35%.paper, 35%. •

• Acidity Acidity oror alkalinity alkalinity (pH): from an average of 1-14, where the more acidic is close to one; and(pH): from an average of 1-14, where the more acidic is close to one; and close to 14 is alkaline. The paper should have a pH of 7 or near a neutral value for printing. close to 14 is alkaline. The paper should have a pH of 7 or near a neutral value for printing. •

• BulkBulk: : Relations between pRelations between papers of the same weight, expapers of the same weight, expressed in cubic centimeters per gramressed in cubic centimeters per gram

1.3

1.3 Paper StructurePaper Structure

Each sheet of paper has a defined structure

Each sheet of paper has a defined structure, which it's the, which it's the direction in which the fibers that compose them are placed. As direction in which the fibers that compose them are placed. As we saw in the

we saw in the previous sections, when the trees are shredded intoprevious sections, when the trees are shredded into fibers and chips, these fall into the

fibers and chips, these fall into the bed of the machine and bybed of the machine and by vibration are aligned in one direction.

vibration are aligned in one direction.

To identify the direction of a sheet of paper, you can use several To identify the direction of a sheet of paper, you can use several methods:

methods: •

• Tear the paper: if the resulting line is straight, that is theTear the paper: if the resulting line is straight, that is the direction of the paper, otherwise the c

direction of the paper, otherwise the cut will be diagonal,ut will be diagonal, or irregular.

or irregular. •

• Fold the paper: take a piece of paper and fold it with someFold the paper: take a piece of paper and fold it with some degree of force (without breaking it, but fold it as tightly degree of force (without breaking it, but fold it as tightly as possible) the paper will tend to curl if it is bent against as possible) the paper will tend to curl if it is bent against its structure.

its structure.

•

• Dampen the paper: when applied a slight amount of waterDampen the paper: when applied a slight amount of water

to a sheet or piece of paper, paper fibers absorb water to a sheet or piece of paper, paper fibers absorb water and expand, generating a slight ripple, to indicate the and expand, generating a slight ripple, to indicate the direction the paper.

direction the paper.

Importance of the Grain Direction or Structure Importance of the Grain Direction or Structure •

• For Pos Press: Depending on the final work to be done, it isFor Pos Press: Depending on the final work to be done, it is necessary that the sheets be folded or cut. It is imperative to necessary that the sheets be folded or cut. It is imperative to know the direction of the

know the direction of the paper before printing, because itpaper before printing, because it must done be in the right direction as not to damage the work must done be in the right direction as not to damage the work done in the Post Press. For

done in the Post Press. For example, a leaflet should be in theexample, a leaflet should be in the direction of the grain, so that the fold is perfectly straight. direction of the grain, so that the fold is perfectly straight. •

• For the final material: If the material produced will be used asFor the final material: If the material produced will be used as media (ei letterhead pages) pages must be printed with

media (ei letterhead pages) pages must be printed with thethe grain, so that when the page goes into a digital printer or grain, so that when the page goes into a digital printer or copier, it will not damaged by

copier, it will not damaged by being bent.being bent.

•

• To print: If the pressure of an offset machine is badlyTo print: If the pressure of an offset machine is badly

calibrated, the force exerted on the paper

calibrated, the force exerted on the paper can damage (ascan damage (as seen in the picture), stretching the material

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2. Ink

2.1 Ink Composition

The ink used in printing is made from three basic ingredients: The ink used in printing is made from three basic ingredients:

Pigments: the chemical substance that gives the ink its color. These make up about 20% of the total Pigments: the chemical substance that gives the ink its color. These make up about 20% of the total volume of ink. The pigments are made especially for each of the Ink manufacturers, by the most volume of ink. The pigments are made especially for each of the Ink manufacturers, by the most important laboratories in the world, given that only 3 or 4 are capable of faithfully reproducing the important laboratories in the world, given that only 3 or 4 are capable of faithfully reproducing the tones necessary for consistent ink through

tones necessary for consistent ink through the ages.the ages.

Varnishes: Varnishes (not be confused with varnishes that are applied at the end of printing) are the Varnishes: Varnishes (not be confused with varnishes that are applied at the end of printing) are the bases of the ink. They are composed of various types of oils and resins and are about 70% of the bases of the ink. They are composed of various types of oils and resins and are about 70% of the volume of ink.

volume of ink.

Additives: Known as the salt and

Additives: Known as the salt and pepper from each producer. These additives change the pepper from each producer. These additives change the properties of properties of the ink, which allows the production of

the ink, which allows the production of different types of ink for different types of ink for each paper type and application.each paper type and application.

2.2 Ink fabrication

The first step in manufacture of ink is the mixture of oils and resins to form the main base, or The first step in manufacture of ink is the mixture of oils and resins to form the main base, or varnishes, and then applying the

varnishes, and then applying the desired pigments.desired pigments.

The second step is to transport the ink to a separated tank to add the additives that makes each ink The second step is to transport the ink to a separated tank to add the additives that makes each ink different, and mix thoroughly.

different, and mix thoroughly.

The final step is to mix the final formula, and pack it in cans, ready to ship to

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Every single ink is different according

Every single ink is different according to its production process and the to its production process and the additives that eachadditives that each

manufacturer uses. It’s impossible to say that one brand is better than others, but it’s a fact that to manufacturer uses. It’s impossible to say that one brand is better than others, but it’s a fact that to mix inks from different brands can lead to troubles in the printing jobs. Each manufacture creates a mix inks from different brands can lead to troubles in the printing jobs. Each manufacture creates a chemical balance in their inks that translates in they physical characteristics (remember, inks are chemical balance in their inks that translates in they physical characteristics (remember, inks are translucent). If two inks aren’t in

translucent). If two inks aren’t in balance, it can lead to balance, it can lead to different and unexpected results.different and unexpected results. 2.3 Ink drying process

2.3 Ink drying process

From the last paragraph, we take that all inks are different, and they are made to match each other, From the last paragraph, we take that all inks are different, and they are made to match each other, and the material in which they will be applied. There is great importance in this aspect, and one of and the material in which they will be applied. There is great importance in this aspect, and one of the main factors is the drying process.

the main factors is the drying process. There are different ways for the ink to dry: There are different ways for the ink to dry:

By Setting: With uncoated papers, most of the ink gets By Setting: With uncoated papers, most of the ink gets absorbed into the material, and dry within

absorbed into the material, and dry within it.it.

By setting and chemical drying: In this method, part of the ink By setting and chemical drying: In this method, part of the ink is absorbed, but not all of it, and the rest reminds on the is absorbed, but not all of it, and the rest reminds on the surface of the material. Over this, most of the time a chemical surface of the material. Over this, most of the time a chemical dryer is applied to keep the ink on the material.

dryer is applied to keep the ink on the material.

100% Chemical Ink: there are materials that don’t have the 100% Chemical Ink: there are materials that don’t have the ability to absorb any of the ink, like plastics and polymers, in ability to absorb any of the ink, like plastics and polymers, in which case, a special chemical dryer is used.

which case, a special chemical dryer is used.

Infrared Reactive Ink: this type of ink reacts to infrared light, Infrared Reactive Ink: this type of ink reacts to infrared light, to aid in the drying process.

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3.

3. Printing Printing TechnologiesTechnologies

3.1 Background

Modern Printing was founded with the Gutenberg Press, from a German inventor who created the Modern Printing was founded with the Gutenberg Press, from a German inventor who created the system of interchangeable type printing. Since then, there has been a continuous evolution of printing system of interchangeable type printing. Since then, there has been a continuous evolution of printing machinery. machinery. Book Printing Book Printing Platten Press: Platten Press:

This type of technology, that in our country is still alive in machines like the Minerva, is a flat-to-flat This type of technology, that in our country is still alive in machines like the Minerva, is a flat-to-flat surface system. While the types are

surface system. While the types are fixed on a stationary bed, ink fixed on a stationary bed, ink is applied to them and another is applied to them and another bedbed moves, applying pressure on the whole surface while leaving the

moves, applying pressure on the whole surface while leaving the impression on the material. This impression on the material. This typetype of technology was useful for small

of technology was useful for small formats and small amounts, but is formats and small amounts, but is severely limited by the strengthseverely limited by the strength that is necessary for the printing (up to 4 tons). These machines had, most of the time, a maximum that is necessary for the printing (up to 4 tons). These machines had, most of the time, a maximum size of 24 x 38 cm. Increasing the format would require to apply almost 16 tons of

size of 24 x 38 cm. Increasing the format would require to apply almost 16 tons of pressure,pressure, something completely out of the possibilities for a

something completely out of the possibilities for a machine of this size.machine of this size.

Cylinder Press: Cylinder Press:

The next step in evolution was the

The next step in evolution was the cylinder press. This replaces the movable bed by cylinder press. This replaces the movable bed by a pressurea pressure

cylinder. By significantly reducing the area where the force is exerted to print, this machine could use cylinder. By significantly reducing the area where the force is exerted to print, this machine could use a bigger paper format; it was faster, with less effort than the old systems (one ton with a larger

a bigger paper format; it was faster, with less effort than the old systems (one ton with a larger format.)

format.)

However, this technology was still far from ideal. The flat form was now the moveable part, which However, this technology was still far from ideal. The flat form was now the moveable part, which wasted a lot of strength, and, being made mostly of lead and other metals, it was incredibly heavy, wasted a lot of strength, and, being made mostly of lead and other metals, it was incredibly heavy, limiting the size of the format and quantity by the sheer force that was needed to move the platform. limiting the size of the format and quantity by the sheer force that was needed to move the platform.

Rotary Press: Rotary Press:

The rotary press was the most important step towards the development of offset. It finally removes The rotary press was the most important step towards the development of offset. It finally removes the use of a m

the use of a movable bed, and instead placed two cylinders which are ovable bed, and instead placed two cylinders which are completely solid, rotating incompletely solid, rotating in opposite directions. This type of system

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3.2

3.2 Letter Letter PressPress

The transition from flat to cylinder press systems could be The transition from flat to cylinder press systems could be achieved only with the development of malleable forms. achieved only with the development of malleable forms. Initially, forms and types were placed in a wooden mold to Initially, forms and types were placed in a wooden mold to create the words and paragraphs. These

create the words and paragraphs. These types were originallytypes were originally made from an alloy of lead, copper and antimony, and

made from an alloy of lead, copper and antimony, and exchanged every time you wanted to

exchanged every time you wanted to print something new.print something new. But manufacturers and printers were still in their desire to But manufacturers and printers were still in their desire to improve their processes, at higher speeds and with

improve their processes, at higher speeds and with largerlarger

formats, like newspapers and magazines. Which was impossible formats, like newspapers and magazines. Which was impossible to achieve with flat beds systems.

to achieve with flat beds systems.

To remedy this situation, engineers at the time devised a way to pass the flat figures to cylindrical To remedy this situation, engineers at the time devised a way to pass the flat figures to cylindrical shapes.

shapes.

The first step was to create a non-readable form of what you wanted to print, with the types in The first step was to create a non-readable form of what you wanted to print, with the types in aa wooden mold.

wooden mold.

With this completed form they imprinted it on a cardboard-like material, which created a readable With this completed form they imprinted it on a cardboard-like material, which created a readable form. The board, being malleable, was then given the

form. The board, being malleable, was then given the cylindrical shape required.cylindrical shape required. Over this mold, it

Over this mold, it was applied a mixture of lead was applied a mixture of lead and copper, to create the and copper, to create the final and non-readablefinal and non-readable plate, ready to print on

plate, ready to print on the desired material.the desired material. The end result was a plate like this:

The end result was a plate like this:

These new forms allowed printing larger

These new forms allowed printing larger quantities in lessquantities in less time, revolutionizing the way information was tr

time, revolutionizing the way information was transmitted.ansmitted. However, the system was not

However, the system was not entirely perfect, as these platesentirely perfect, as these plates were made of lead, a

were made of lead, a material that eventually became knownmaterial that eventually became known as toxic, and that even at the time was heavy, and soft in as toxic, and that even at the time was heavy, and soft in comparison with other metals. Its use was limited because the comparison with other metals. Its use was limited because the letters and forms wore out. The speed was also limited by the letters and forms wore out. The speed was also limited by the weight of the form; therefore,

weight of the form; therefore, at higher revolutions, theat higher revolutions, the piece tended to separate from the c

piece tended to separate from the cylinder by centrifugalylinder by centrifugal force, and could generate large damage to

force, and could generate large damage to machines ormachines or operators.

operators.

The typography presses operated with the pressure between the lead The typography presses operated with the pressure between the lead plate (higher cylinder in the photo), against a soft cylinder (bottom plate (higher cylinder in the photo), against a soft cylinder (bottom cylinder), usually made of rubber, this extended the life of the plate, cylinder), usually made of rubber, this extended the life of the plate, and achieved a better impression, for the paper printed was less and achieved a better impression, for the paper printed was less damaged than if both cylinders were completely solid.

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3.3 Flexography

In the early twentieth century, flexography was

In the early twentieth century, flexography was born in two different placesborn in two different places almost simultaneously: in France, invented by engineer Houleg, and Great almost simultaneously: in France, invented by engineer Houleg, and Great Britain, Liverpool, patented by the printing house 'Bibby, Baron

Britain, Liverpool, patented by the printing house 'Bibby, Baron and children', inand children', in 1905.

1905.

This system changes the way

This system changes the way the production of plate, by replacing lead withthe production of plate, by replacing lead with rubber, and the soft cylinder and a

rubber, and the soft cylinder and a solid cylinder.solid cylinder.

The new plate was lighter, allowing faster printing; it was easier to replace, The new plate was lighter, allowing faster printing; it was easier to replace, increasing the number of copies, and it

increasing the number of copies, and it allowed to print materials onceallowed to print materials once considered impossible, such as plastics and metals. The inks also

considered impossible, such as plastics and metals. The inks also had to evolve,had to evolve, becoming less dense.

becoming less dense.

The quality, however, suffered with this step. As the ink grew thinner, and the The quality, however, suffered with this step. As the ink grew thinner, and the materials couldn't absorb ink, it started to generate an effect called 'squash', as materials couldn't absorb ink, it started to generate an effect called 'squash', as the ink tends to run down and created an uneven impression. As technique the ink tends to run down and created an uneven impression. As technique evolved, these problems were declining.

evolved, these problems were declining. 3.4

3.4 Offset Offset PrintingPrinting

Offset Printing is, perhaps, the most important

Offset Printing is, perhaps, the most important development in the industry, becoming the most useddevelopment in the industry, becoming the most used printing technique throughout the world by the 50s,

printing technique throughout the world by the 50s, and it's still to this and it's still to this day.day. Offset printing was created in

Offset printing was created in 1875, with Robert Barclay, whose development allowed the transfer 1875, with Robert Barclay, whose development allowed the transfer of of an aluminum plate to a rubber body. It was 1907, when a printer of New Jersey, Ira Washington Rubel an aluminum plate to a rubber body. It was 1907, when a printer of New Jersey, Ira Washington Rubel discovered that when transferring the image of

discovered that when transferring the image of a plate to the rubber, and a plate to the rubber, and then to paper, the imagethen to paper, the image was of much better quality.

was of much better quality. Today, all printers are familiar

Today, all printers are familiar with the Offset Printing Process, which with the Offset Printing Process, which uses three Cylinders (plate,uses three Cylinders (plate, rubber and steel) to generate an impression on

rubber and steel) to generate an impression on the paper.the paper.

Plate: an aluminum foil on which it

Plate: an aluminum foil on which it generates a chemical emulsion,generates a chemical emulsion, thus transmitting a positive image (of a negative or directly with CTP), thus transmitting a positive image (of a negative or directly with CTP), which is intended to print. For color prints, you create a plate for which is intended to print. For color prints, you create a plate for each color used, and then have the

each color used, and then have the combination to generate the finalcombination to generate the final print. The offset printing process depends on the

print. The offset printing process depends on the perfect combinationperfect combination on this cylinder of water and ink.

on this cylinder of water and ink. Rubber or blanket: On this, the plate

Rubber or blanket: On this, the plate makes a non-readablemakes a non-readable impression. The blanket is one piece, usually made of

impression. The blanket is one piece, usually made of rubber or otherrubber or other soft material, which is responsible for transmitting the image to the soft material, which is responsible for transmitting the image to the media.

media.

Steel: This cylinder is responsible for generating the pressure between Steel: This cylinder is responsible for generating the pressure between the blanket and the material to

the blanket and the material to achieve the final print.achieve the final print. Besides the three main cylinders, Offset machines have

Besides the three main cylinders, Offset machines have two separatetwo separate batteries of rollers: A battery of ink rollers and another of water batteries of rollers: A battery of ink rollers and another of water

rollers, which are in contact with the plate. Offset printing relies on a rollers, which are in contact with the plate. Offset printing relies on a precise balance between water and ink. The emulsion on

precise balance between water and ink. The emulsion on the platesthe plates should only receive ink, so the rest of the plate must be covered by should only receive ink, so the rest of the plate must be covered by water. Not only water is responsible for ensuring the sharpness of the water. Not only water is responsible for ensuring the sharpness of the impression (for which it must

impression (for which it must have a precise chemical composition),have a precise chemical composition), but also fulfills the function of cooling the

but also fulfills the function of cooling the machine to prevent it frommachine to prevent it from overheating and damage.

overheating and damage.

This technique solved the problems of the past: the

This technique solved the problems of the past: the materials used were light (aluminum plates,materials used were light (aluminum plates, rubber for the blanket and the

rubber for the blanket and the steel one was the only completely solid csteel one was the only completely solid cylinder), allowing to print atylinder), allowing to print at higher speeds, the pressure needed for printing was smaller, which

higher speeds, the pressure needed for printing was smaller, which saved energy and did not harm saved energy and did not harm thethe material.

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3.5

3.5 Gravure Gravure PrintingPrinting

The rotogravure is a

The rotogravure is a very specialized technique, as its use is limited to very specialized technique, as its use is limited to highhigh volume runs.

volume runs.

Like flexography and letterpress printing, rotogravure uses only tw

Like flexography and letterpress printing, rotogravure uses only tw o cylinders, oneo cylinders, one hard solid that acts as a plate and a soft one to apply the pressure. However, this hard solid that acts as a plate and a soft one to apply the pressure. However, this method does not use a mold or plate but it physically engraves the image onto a method does not use a mold or plate but it physically engraves the image onto a copper cylinder. This process is expensive because it

copper cylinder. This process is expensive because it uses a cylinder for each uses a cylinder for each colorcolor for each design, and they aren't

for each design, and they aren't as replaceable as in typography. Therefore, thisas replaceable as in typography. Therefore, this technique is only used in high volume runs, and

technique is only used in high volume runs, and with paper reels, not sheets. Thewith paper reels, not sheets. The rotogravure printing is generally used for

rotogravure printing is generally used for magazines sold nationally or globally.magazines sold nationally or globally.

3.6 Screen Printing

Screen-printing

Screen-printing is a printing technique that uses a is a printing technique that uses a woven mesh to support an inkwoven mesh to support an ink-blocking stencil.-blocking stencil. The attached stencil forms open areas of mesh that transfer ink as a sharp-edged image onto a The attached stencil forms open areas of mesh that transfer ink as a sharp-edged image onto a substrate. A roller or squeegee is moved across the screen stencil, forcing or pumping ink past the substrate. A roller or squeegee is moved across the screen stencil, forcing or pumping ink past the threads of the woven mesh in

threads of the woven mesh in the open areas.the open areas.

Screen-printing is also a stencil method of

Screen-printing is also a stencil method of print makingprint making in which a design is imposed on a screen of silk or other in which a design is imposed on a screen of silk or other fine mesh, with blank areas coated

fine mesh, with blank areas coated with an impermeablewith an impermeable substance, and ink is forced through

substance, and ink is forced through the mesh onto thethe mesh onto the printing surface. It is also known as

printing surface. It is also known as Screen PrintingScreen Printing,, silkscreen

silkscreen,, serigraphyserigraphy, and, and serigraphserigraph..

A screen is made of a piece of porous, finely woven fabric called mesh stretched over a frame of A screen is made of a piece of porous, finely woven fabric called mesh stretched over a frame of aluminum or wood. Currently most mesh is made of man-made materials such as steel, nylon, and aluminum or wood. Currently most mesh is made of man-made materials such as steel, nylon, and polyester. Areas of the screen are blocked off with a non-permeable material to form a stencil, which polyester. Areas of the screen are blocked off with a non-permeable material to form a stencil, which is a negative of the image to be printed; that is, the open spaces are where the ink will appear.

is a negative of the image to be printed; that is, the open spaces are where the ink will appear.

The screen is placed atop a substrate such as paper or fabric. Ink is placed on top of the screen, and a The screen is placed atop a substrate such as paper or fabric. Ink is placed on top of the screen, and a fill bar (also known as a flood bar) is used to fill the mesh openings with ink. The operator begins with fill bar (also known as a flood bar) is used to fill the mesh openings with ink. The operator begins with the fill bar at the rear of the screen and behind a reservoir of ink. The operator lifts the screen to the fill bar at the rear of the screen and behind a reservoir of ink. The operator lifts the screen to prevent contact with the substrate and

prevent contact with the substrate and then using a slight amount of then using a slight amount of downward force pulls the fill bardownward force pulls the fill bar to the front of

to the front of the screen. This effectively fills the mesh the screen. This effectively fills the mesh openings with ink and moves the inkopenings with ink and moves the ink

reservoir to the front of the screen. The operator then uses a rubber blade to move the mesh down to reservoir to the front of the screen. The operator then uses a rubber blade to move the mesh down to the substrate and pushes the squeegee to the rear

the substrate and pushes the squeegee to the rear of the screen. The of the screen. The ink that is in ink that is in the mesh openingthe mesh opening is pumped or squeezed by capillary action to

is pumped or squeezed by capillary action to the substrate in a controlled and the substrate in a controlled and prescribed amount, i.e.prescribed amount, i.e. the wet ink deposit is proportional to

the wet ink deposit is proportional to the thickness of the mesh and the thickness of the mesh and or stencil. As the or stencil. As the squeegee movessqueegee moves toward the rear of the screen the tension of the mesh pulls the mesh up away from the substrate toward the rear of the screen the tension of the mesh pulls the mesh up away from the substrate (called snap-off) leaving the ink upon the substrate surface.

(called snap-off) leaving the ink upon the substrate surface.

There are three common types of screen printing presses.: The 'flat-bed', 'cylinder', and the most There are three common types of screen printing presses.: The 'flat-bed', 'cylinder', and the most widely used type, the 'rotary'.

widely used type, the 'rotary'.

This technique will be used for printing large

This technique will be used for printing large and many ink volumes on paper and many ink volumes on paper and to print on materialsand to print on materials like plastic, carton, glasses, wood, iron and so on up to the thickness of 5 cm. In other words: every like plastic, carton, glasses, wood, iron and so on up to the thickness of 5 cm. In other words: every material which is not easy to fold around cylinders.

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4.

4. Color Color in in PrintingPrinting

Offset printing, and all types of printing, depends on creating an image from Offset printing, and all types of printing, depends on creating an image from thousands or even millions of small dots. For colors, most printers are limited thousands or even millions of small dots. For colors, most printers are limited to create from the combination of basic colors, Cyan, Magenta, Yellow and to create from the combination of basic colors, Cyan, Magenta, Yellow and Black. From these four colors, a printer can create most of the color gamut, a Black. From these four colors, a printer can create most of the color gamut, a process that is explained below. The color sequence will almost always be process that is explained below. The color sequence will almost always be Cyan, Magenta, Yellow and Black.

Cyan, Magenta, Yellow and Black.

4.1 Color Mixing

The color is a property of each object, which reflects a specific color when light falls upon it. For The color is a property of each object, which reflects a specific color when light falls upon it. For computers or printers to generate color, they must deceive the human eye with a mixture of colors. computers or printers to generate color, they must deceive the human eye with a mixture of colors. Computers, televisions and any type of display used additive mix, while printers

Computers, televisions and any type of display used additive mix, while printers use the subtractive.use the subtractive.

In additive color mixing, light of

In additive color mixing, light of different colors is superimposed. If all thedifferent colors is superimposed. If all the colors of the spectrum are superimposed, this results in the color white, in colors of the spectrum are superimposed, this results in the color white, in the absent of them all, black

the absent of them all, black is the result.is the result.

The additive primary colors are red, green and blue. Each of these The additive primary colors are red, green and blue. Each of these represents one-third of the visible spectrum.

represents one-third of the visible spectrum. The principle of additive color mixing c

The principle of additive color mixing can be clearly illustrated using threean be clearly illustrated using three slide projectors. Each projector generates a circle of light on a screen in one slide projectors. Each projector generates a circle of light on a screen in one of the three additive primary colors. Additive color mixing is used in

of the three additive primary colors. Additive color mixing is used in television broadcasts, lcd computer screens, etc.

television broadcasts, lcd computer screens, etc. 4.1.1 Additive Color Mixing

4.1.1 Additive Color Mixing

4.1.2 Subtractive Color Mixing

Subtractive color mixing removes different color components from white light. When all color Subtractive color mixing removes different color components from white light. When all color components have been removed, the result is black.

components have been removed, the result is black.

The subtractive primary colors are cyan, magenta and yellow. Each of them represents two-thirds of The subtractive primary colors are cyan, magenta and yellow. Each of them represents two-thirds of the visible spectrum.

the visible spectrum.

Subtractive Color Mixing: Subtractive Color Mixing: Cyan + Yellow = Green Cyan + Yellow = Green Yellow + Magenta = Red Yellow + Magenta = Red Magenta + Cyan = Blue Magenta + Cyan = Blue

Cyan + Magenta + Yellow = Black Cyan + Magenta + Yellow = Black No color = White

No color = White

They can be generated by removing one additive primary color from white light (e.g. with a filter) or They can be generated by removing one additive primary color from white light (e.g. with a filter) or by superimposing two additive primary colors.

by superimposing two additive primary colors.

Printing inks are translucent substances that function as color filters. Which color do you get if you Printing inks are translucent substances that function as color filters. Which color do you get if you print a blue-absorbing substance on a white paper?

print a blue-absorbing substance on a white paper? Blue is removed from the

Blue is removed from the white light; the other components (green and rwhite light; the other components (green and red) are reflected. Theed) are reflected. The additive combination of these two colors r

additive combination of these two colors results in yellow:esults in yellow: This is the color we see.

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The ink has thus subtracted a

The ink has thus subtracted a third (blue) from the white light third (blue) from the white light (consisting(consisting of red, green and blue).

of red, green and blue).

Assume two transparent substances are overprinted. For

Assume two transparent substances are overprinted. For example, let usexample, let us take the inks yellow and cyan. These two substances first filter the blue take the inks yellow and cyan. These two substances first filter the blue component from the white light and

component from the white light and then the red component. We see thethen the red component. We see the resulting light as green. The two inks have subtracted two thirds of the resulting light as green. The two inks have subtracted two thirds of the color components from the white light.

color components from the white light. If cyan, magenta and yellow

If cyan, magenta and yellow are overprinted, all the incident light isare overprinted, all the incident light is absorbed (i.e. there is no reflection).

absorbed (i.e. there is no reflection). We see black.

We see black.

Color images are printed with cyan, magenta, yellow and black inks. The black ink improves the Color images are printed with cyan, magenta, yellow and black inks. The black ink improves the definition and feeling of depth in images. Also, the

definition and feeling of depth in images. Also, the black that is produced by black that is produced by combining cyan,combining cyan, magenta and yellow is never a

magenta and yellow is never a really deep black due to the pigments really deep black due to the pigments used in the inks.used in the inks.

4.2 Color Separation

As we have seen, to print a color image, it must first As we have seen, to print a color image, it must first be separated into the four basic colors: Cyan,

be separated into the four basic colors: Cyan, Magenta, Yellow and Black. Even if the

Magenta, Yellow and Black. Even if the previous threeprevious three could form the black, it never generates an image as could form the black, it never generates an image as sharp as when used separately.

sharp as when used separately.

As shown in the image, when each color is separated, As shown in the image, when each color is separated, and then we print them in a set order, you create a and then we print them in a set order, you create a color image of high quality. In order to separate the color image of high quality. In order to separate the colors we use filters. As

colors we use filters. As explained in the previousexplained in the previous paragraph, for each CMY color their opposite RGB paragraph, for each CMY color their opposite RGB color is used as a filter, for example, the filter for color is used as a filter, for example, the filter for Magenta is green, for cyan is red, and for yellow the Magenta is green, for cyan is red, and for yellow the blue filter is used.

blue filter is used.

Once you have four separate colors, a plate is created Once you have four separate colors, a plate is created for each, and you can proceed to printing.

for each, and you can proceed to printing.

4.3 Ink Thickness

The thickness is the measure of the amount of ink that has been The thickness is the measure of the amount of ink that has been applied to a sheet of paper. I

applied to a sheet of paper. It’s measured by height of the t’s measured by height of the inkink layer on a sheet.

layer on a sheet.

Inks are translucent rather than

Inks are translucent rather than opaque. Light penetrates into theopaque. Light penetrates into the ink, when passing through; it strikes

ink, when passing through; it strikes pigments that absorb apigments that absorb a greater or lesser part of certain wavelengths.

greater or lesser part of certain wavelengths.

Depending on the pigment concentration and thickness of the Depending on the pigment concentration and thickness of the ink,ink, the light strikes a larger or smaller number of pigments; this

the light strikes a larger or smaller number of pigments; this absorbs different portions of the light. The

absorbs different portions of the light. The light beams finallylight beams finally reach the surface of the substrate and are reflected by it. The reach the surface of the substrate and are reflected by it. The light must pass through the ink film again before it reaches the light must pass through the ink film again before it reaches the eye.

eye.

A thick layer of ink absorbs more light components and reflects fewer than a thin layer; the observer A thick layer of ink absorbs more light components and reflects fewer than a thin layer; the observer therefore sees a darker and more saturated color tone. The light component arriving at the viewer’s therefore sees a darker and more saturated color tone. The light component arriving at the viewer’s

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4.4 Densities

It’s the degree to which an ink layer is impermeable to light. On a theoretical level, this is the It’s the degree to which an ink layer is impermeable to light. On a theoretical level, this is the relationship between a measurement on unprinted paper and a measurement on printed-paper.

relationship between a measurement on unprinted paper and a measurement on printed-paper. The density and ink thickness relationship is very

The density and ink thickness relationship is very important to maintain the quality important to maintain the quality of the printings.of the printings. The more ink we use, the higher density value, but, as the ink film grows thicker, it creates a

The more ink we use, the higher density value, but, as the ink film grows thicker, it creates a polluted color. Remember that ink is tr

polluted color. Remember that ink is translucent, and the more ink the light anslucent, and the more ink the light has to go though, thehas to go though, the less light will come out, and the color will look dark and dirty (see image).

less light will come out, and the color will look dark and dirty (see image).

The first stage in offset printing, it is the correct feeding of paper into the The first stage in offset printing, it is the correct feeding of paper into the machine. On this aspect, which at

machine. On this aspect, which at first glance may seem first glance may seem simple, depends thesimple, depends the good print quality, maintaining the material safe, getting

good print quality, maintaining the material safe, getting a good register,a good register, and many more.

and many more.

As a rule, in modern machines offset, three guides to be used for the entry of As a rule, in modern machines offset, three guides to be used for the entry of the paper. One side and two

the paper. One side and two front guides.front guides.

Although the machines have up to 8 front Guides, but only two must be used, Although the machines have up to 8 front Guides, but only two must be used, placing them a fourth in from each end of the paper. This way we ensure placing them a fourth in from each end of the paper. This way we ensure that the paper gets it

that the paper gets it straight, without bending or leaning to one straight, without bending or leaning to one side orside or another. another. 5. Offset 5. Offset 5.1 Paper feed 5.1 Paper feed

The space between the side guides and the paper

The space between the side guides and the paper should be 3-4should be 3-4 mm, to give the paper enough space to accommodate their mm, to give the paper enough space to accommodate their movement. Also, this is the same

movement. Also, this is the same distance that must exist betweendistance that must exist between the stack of paper and the suction cups on the tray.

the stack of paper and the suction cups on the tray.

5.1.1 Single sheet feeder

Examples of machines using this system are

Examples of machines using this system are the Heidelberg GTOthe Heidelberg GTO or Kor, older offset technologies, which can print up to 8,000 or Kor, older offset technologies, which can print up to 8,000 sheets per hour.

sheets per hour.

This is due in part to the type of feeding they use. In this system This is due in part to the type of feeding they use. In this system the paper enters the machine one sheet at a time, where a the paper enters the machine one sheet at a time, where a suction cup lifts the paper from the stack, and delivers it to two suction cup lifts the paper from the stack, and delivers it to two mechanical clips that take you

mechanical clips that take you inside the printer. As the suckerinside the printer. As the sucker is in the edge of the machine, it has to wait that each sheet is in the edge of the machine, it has to wait that each sheet ends its journey to start moving the next. Then the sheet is ends its journey to start moving the next. Then the sheet is taken by the feed gripper, which

taken by the feed gripper, which executes a pendulumexecutes a pendulum

movement, which at one time carried the paper to the press, movement, which at one time carried the paper to the press, and the next should return to

and the next should return to take the next, wasting half thetake the next, wasting half the energy.

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5.1.2 Stream feeder

A more modern system for feeding paper in offset A more modern system for feeding paper in offset printing presses, is the stream feeder, as

printing presses, is the stream feeder, as used by theused by the Heidelberg SOR and Speedmasters, Mitsubishi, and

Heidelberg SOR and Speedmasters, Mitsubishi, and otherother modern press manufacturers. This system places

modern press manufacturers. This system places thethe suction cup to the end of

suction cup to the end of the pile and "pushes" thethe pile and "pushes" the sheets; it doesn't wait for

sheets; it doesn't wait for the sheet to be completelythe sheet to be completely gone, and send the following. It has also

gone, and send the following. It has also replaced thereplaced the feed gripper with a conveyor

feed gripper with a conveyor belt, where rollers apply abelt, where rollers apply a bit of force to the material and push it into the press. bit of force to the material and push it into the press.

This system allows the machines to operate at speeds up to 18,000 This system allows the machines to operate at speeds up to 18,000 sheets per hour. It also has the advantage that, by the way the sheets per hour. It also has the advantage that, by the way the cylinders are placed internally, allows the paper to

cylinders are placed internally, allows the paper to enter moreenter more easily, preventing it from bending and damage. As

easily, preventing it from bending and damage. As can be seen in thecan be seen in the figure:

figure:

In the first figure,

In the first figure, the transport cylinder receives the paper, insteadthe transport cylinder receives the paper, instead of the steel. This cylinder is

of the steel. This cylinder is not perfectly round, allowing space fornot perfectly round, allowing space for the swing gripper to transport the paper without damaging it.

the swing gripper to transport the paper without damaging it.

This picture below describes the operation of

This picture below describes the operation of a machine SpeedMastera machine SpeedMaster system. This is what

system. This is what regulates the supply of paper into the regulates the supply of paper into the machine.machine. It is a very complex system consisting of several steps:

It is a very complex system consisting of several steps:

•

• Air is blown to separate the sheet from the pileAir is blown to separate the sheet from the pile •

• The first sucker takes the sheetThe first sucker takes the sheet •

• The governor foot applies pressure on the The governor foot applies pressure on the rest of the pile, preventingrest of the pile, preventing them from joining the first and blows air to completely separate the them from joining the first and blows air to completely separate the sheet above.

sheet above.

•

• The second sucker takes the sheThe second sucker takes the sheet, and brings it et, and brings it to the feeding table,to the feeding table,

which it's then taken by the rollers and the moving belt which it's then taken by the rollers and the moving belt 5.2

5.2 Offset Offset MachinesMachines

Heidelberg – Speed Master Heidelberg – Speed Master

4-color press, with a stream feed system. This is a classic example of a modern printing machine. 4-color press, with a stream feed system. This is a classic example of a modern printing machine. It has a stream feed system, and it can be seen as the input and output trays have been elevated to It has a stream feed system, and it can be seen as the input and output trays have been elevated to allow a continuous work without stopping the machine every time it runs out of paper. Its speed allow a continuous work without stopping the machine every time it runs out of paper. Its speed reaches 15,000 sheets per hour.

reaches 15,000 sheets per hour. Each color towers have

Each color towers have a three-cylinder configuration: plate, blanket and steel, and a set a three-cylinder configuration: plate, blanket and steel, and a set of threeof three transporters cylinders between each tower.

transporters cylinders between each tower. The main problem with this

The main problem with this machine is the size of trmachine is the size of transporter cylinders, being so small, the paperansporter cylinders, being so small, the paper bends too much in its passage through the machine, preventing the use of thicker materials such as bends too much in its passage through the machine, preventing the use of thicker materials such as cardboard or others.

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KBA – Rapida 105 KBA – Rapida 105

In response to the Heidelberg problem, the competition developed ways to

In response to the Heidelberg problem, the competition developed ways to improve and differentiateimprove and differentiate themselves from others.

themselves from others.

The printing system is essentially the same, a configuration of three cylinders for each color tower. The printing system is essentially the same, a configuration of three cylinders for each color tower. However, the shape of the steel and tr

However, the shape of the steel and transportation cylinders, by replacing the three used in theansportation cylinders, by replacing the three used in the SpeedMaster with just one, allows a freer flow of paper through the machine. This type of machine SpeedMaster with just one, allows a freer flow of paper through the machine. This type of machine can printed cartons and all types of papers.

can printed cartons and all types of papers.

The shape of the transportation cylinder allows it to move two sheet for each revolution, saving The shape of the transportation cylinder allows it to move two sheet for each revolution, saving energy and improving the process.

energy and improving the process.

Heidelberg – Speed Master CD Heidelberg – Speed Master CD

In response to the previous machine, Heidelberg developed this new system, based on

In response to the previous machine, Heidelberg developed this new system, based on the design of athe design of a single transport cylinder, trying to improve

single transport cylinder, trying to improve it it by increasing the size of this, by increasing the size of this, and the number of sheetsand the number of sheets transported per revolution.

transported per revolution.

With this, the company had a machine that could print on any material, with the same printing system With this, the company had a machine that could print on any material, with the same printing system as the one previously used.

as the one previously used.

Man Roland – 4 colors Man Roland – 4 colors

Leaving the 3 cylinders configuration, Man Roland (since the

Leaving the 3 cylinders configuration, Man Roland (since the development of this machine has beendevelopment of this machine has been separated into two different companies) sought to differentiate their products

separated into two different companies) sought to differentiate their products with a 5-cylinderwith a 5-cylinder configuration: two plates, two blankets and one steel

configuration: two plates, two blankets and one steel cylinder. Thus, it printed two colors cylinder. Thus, it printed two colors on eachon each tower, reducing the number of moving

tower, reducing the number of moving parts, and making the process parts, and making the process more efficient.more efficient.

See as each transport cylinder is connected to the next tower by a system of chains, which are See as each transport cylinder is connected to the next tower by a system of chains, which are responsible for mobilizing the sheets of paper.

responsible for mobilizing the sheets of paper.

Today Roland no longer makes these machines, focusing on the traditional configuration of three Today Roland no longer makes these machines, focusing on the traditional configuration of three cylinders configuration.

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Heidelberg GTO 52-2 Heidelberg GTO 52-2

This press will go down in history as the machine that saw This press will go down in history as the machine that saw the industry grow. Though now

the industry grow. Though now seen as an inefficientseen as an inefficient machine, with a maximum speed of

machine, with a maximum speed of 8,000 sheets per hour,8,000 sheets per hour, this printer at the time allowed for the growth of large this printer at the time allowed for the growth of large printing houses, while cemented the dominance of printing houses, while cemented the dominance of Heidelberg in the field of small formats.

Heidelberg in the field of small formats.

A two-color machine, you can see how the input and output A two-color machine, you can see how the input and output piles are shorter, and used the same set of three cylinders to piles are shorter, and used the same set of three cylinders to carry the sheet from one tower to another.

carry the sheet from one tower to another.

5.3 Alternative Technologies

Heidelberg and the other major offset press manufacturers

Heidelberg and the other major offset press manufacturers were competing not only against were competing not only against eacheach other, but also against the digital revolution. Gradually digital printing

other, but also against the digital revolution. Gradually digital printing was taking over small printwas taking over small printinging jobs, leaving printers without customers, and therefore, making larger

jobs, leaving printers without customers, and therefore, making larger presses ineffective.presses ineffective. The office works were

The office works were becoming more common, and large becoming more common, and large printing runs, as magazines and advertising,printing runs, as magazines and advertising, were declining. It was the duty of manufacturers to develop new forms of print, to cope with this were declining. It was the duty of manufacturers to develop new forms of print, to cope with this change.

change.

While they may always be classified as offset, these new printing techniques radically change the While they may always be classified as offset, these new printing techniques radically change the method of work. Some were successful, others not.

method of work. Some were successful, others not. 5.3.1 Quickmaster DI 46-4

5.3.1 Quickmaster DI 46-4

In response to color c

In response to color copiers, Heidelberg developmenopiers, Heidelberg developmentt offset machines capable of printing small format

offset machines capable of printing small format in fullin full color without taking up too much space, since its

color without taking up too much space, since its intention was that for the machine to be inside an intention was that for the machine to be inside an office.

office.

The Quickmaster occupied a Direct Imaging System, or The Quickmaster occupied a Direct Imaging System, or DI for short.

DI for short. The machine should be connected directlyThe machine should be connected directly to the computer, so this would send the design to be to the computer, so this would send the design to be printed. Laser equipment would engrave the image on printed. Laser equipment would engrave the image on each special prepared cylinder, which was not in a each special prepared cylinder, which was not in a traditional plate, but a cylinder coated with

traditional plate, but a cylinder coated with a layera layer reactive to lasers, which could have

reactive to lasers, which could have to be completedto be completed removed to implement a new design.

removed to implement a new design.

The Quickmaster used a satellite configuration; it

The Quickmaster used a satellite configuration; it occupied a single steel cylinder for four occupied a single steel cylinder for four blanketsblankets and four plate cylinders (9 cylinders in

and four plate cylinders (9 cylinders in total).total).

The main factor against this machine was the high cost of operation. If a plate was damaged, the The main factor against this machine was the high cost of operation. If a plate was damaged, the production should be stopped while the printer erased the cylinder, and

production should be stopped while the printer erased the cylinder, and engraved on a new image, aengraved on a new image, a process that took quite some time.

process that took quite some time.

This drawback ended up taking it out of the market, as it never achieved a competitive advantage This drawback ended up taking it out of the market, as it never achieved a competitive advantage against digital Systems.

against digital Systems.

5.3.2

5.3.2 Printmaster Printmaster QM QM 46-246-2

A new Heidelberg attempt, to compete

A new Heidelberg attempt, to compete against digital technology, led to the development of theagainst digital technology, led to the development of the Printmaster. This time, the German company's engineers returned to work the traditional way, with Printmaster. This time, the German company's engineers returned to work the traditional way, with

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Its limitation was the quality: Using a 4-cylinder Its limitation was the quality: Using a 4-cylinder configuration, with two plates on a single blanket, the configuration, with two plates on a single blanket, the combination of both colors on the plastic material of the combination of both colors on the plastic material of the blanket causes color contamination in the more complex blanket causes color contamination in the more complex designs. This machine was designed for simple jobs, such designs. This machine was designed for simple jobs, such as custom paper, color prints or presentation cards, for as custom paper, color prints or presentation cards, for which the Printmaster was efficient and effective. This which the Printmaster was efficient and effective. This technology is still marketed, enjoying success in small and technology is still marketed, enjoying success in small and specialized office work.

specialized office work.

5.4 Drying Systems in offset machines.

The development in printing technologies The development in printing technologies

follows two main criteria: improving quality and follows two main criteria: improving quality and reducing time

reducing time..

For these reasons, manufacturers began to For these reasons, manufacturers began to place large drying systems in their printers. place large drying systems in their printers. Thus, at the same time that the sheets pass Thus, at the same time that the sheets pass through the machine they get dry and are ready through the machine they get dry and are ready to be handled in the Post Press.

to be handled in the Post Press. For example, the image #1 is the

For example, the image #1 is the HeidelbergHeidelberg Speedmaster 52

Speedmaster 52, a four-colors machine that, a four-colors machine that has a drying system attached at the end. In the has a drying system attached at the end. In the second image one can appreciate the added second image one can appreciate the added space, between the last transfer cylinder and space, between the last transfer cylinder and the output tray.

the output tray. A set of Infrared A set of Infrared lights (represented lights (represented asas the red line in the images)

the red line in the images) has been placed to acceleratehas been placed to accelerate the drying as the paper goes through, led by the grips in the drying as the paper goes through, led by the grips in the chains.

the chains. Other systems use a Other systems use a set of UV lights, set of UV lights, toto achieve the same effect.

achieve the same effect.

These equipments also facilitate the work of

These equipments also facilitate the work of varnishing,varnishing, especially in machines of 5 or 6 towers, where one can especially in machines of 5 or 6 towers, where one can make the whole process (printing, coating and

make the whole process (printing, coating and drying) in adrying) in a single run.

single run.

The drying systems can be applied to many types of The drying systems can be applied to many types of

machines, according to the needs of the printer. One can have a drying system in a six-color machine, machines, according to the needs of the printer. One can have a drying system in a six-color machine, as well as in a one-color machine. These systems are parts that must be ordered directly from the as well as in a one-color machine. These systems are parts that must be ordered directly from the factory, before the machine is

factory, before the machine is assembled, it is not possible to add these types assembled, it is not possible to add these types of systems according toof systems according to one own schedule.

one own schedule.

5.5

5.5 Water in Water in Offset Offset PrintingPrinting

As it was seen in the 3.4 point, the Offset Printing depends on a delicate balance of water and ink. As it was seen in the 3.4 point, the Offset Printing depends on a delicate balance of water and ink. The water must cover all the surface of the plate where there isn’t any emulsion (which must be The water must cover all the surface of the plate where there isn’t any emulsion (which must be covered with ink). To make this happen, the water must have a perfect Chemicals composition, covered with ink). To make this happen, the water must have a perfect Chemicals composition,