The GATF
`Encyclopedia of
`Graphic
`Communications
`
`Richard M. Roman©
`Editor-in-Chie
`
`Frank. J. Roman©
`Editor-
`
`Peter Oresick
`Director, GMT Press
`
`Thomas M. Destree, Erika L. Kendra
`Associate Editors
`
`Robert J. Romano
`Technical Illustrator
`
`GATFPress
`Pittsburgh
`
`Petitioner - Owens Corning
`Ex. 1012, p. 1 of 10
`
`

`

`Copyright 1998
`Graphic Arts Technical Foundation
`All Rights Reserved
`
`Library of Congress Catalog Card Number: 97-74138
`International Standard Book Number: 0-88362-190-8
`International Standard Book Number 0-88362-21ii-7 (Leather-Bound Edition]
`
`Printed in the United States of America
`
`Order No. 1306
`
`Reproduction in any means without specific permission is prohibited.
`
`Product names are mentioned in this book as a matter of information only and du not
`imply endorsement by the Graphic Arts Technical Foundation.
`
`GATFPress
`Graphic Arts Technical Foundation
`200 Deer Run Road
`Sewickley, PA 15143-2600
`Phone: 412/741-6860
`Fax.: 412/741-2311
`http://www.gatf
`
`
`
`Petitioner - Owens Corning
`Ex. 1012, p. 2 of 10
`
`

`

`Graphics Scanner
`
`Graphics Scanner
`See Scanner.
`
`'Graphics Terminal
`-la computing, a monitor or terminal capable of displaying
`pictures or other images, either in raster form or, less com-
`monly, vector form. Some common graphics terminals of
`the recent past have included the CGA, EGA, VGA, etc.
`
`...Graphic Visualization
`A means of presenting data—such as in scientific and engi-
`neering research—in a graphic or visual way, such as by
`means of charts, graphs, etc. Often, data from spreadsheet
`or database programs can be imported into graphics pro-
`;.: grams that will facilitate its conversion to visual form.
`
`Graphic Window
`In computing, a pixel matrix or grid in which each pixel
`can be specified by the user as either black or white,
`
`Grave Accent
`In typography, a left-pointing accent (*) placed over a char-
`-. atter such as "e." The accent pointing in the opposite direc-
`tion is called an acute accent. See Accent.
`
`Gravure
`A printing method that utilizes engraved cylinders or,
`infrequently, cylinder-mounted plates as the image carri-
`ers. The image areas are etched into the surface of the
`cylinder as a collection of tiny cells. The cylinder rotates in
`an ink fountain and ink collects in the cells, the excess ink
`being scraped from the nonimage areas by a doctor blade.
`The paper (or other substrate) is passed between the
`
`Impression
`Roller
`
`1'
`Doclor Substrate
`Blade
`
`Etched
`CaNs
`
`Ink
`Fountain
`4— Ink
`
`The gravure printing unit.
`
`gravure cylinder and a rubber-coated impression roller,
`and ink is transferred by a combination of capillary action
`and the pressing of the substrate into the engraved cells of
`the cylinder, helped by the rubber surface of the impression
`roller. Most gravure printing performed today is web-fed
`rotogravure printing, with occasional sheetfed use.
`Gravure is also well-suited to the printing of packaging on
`a variety of nonpeper substrates.
`
`Gravure
`
`Doctor Blade
`
`The two basics af gravure printing—the recessed image and
`the doctor blade.
`
`Gravure printing is a direct descendent of older
`intaglio printing (gravure and intaglio, commonly used syn-
`onymously, are different processes; all gravure printing is
`intaglio, yet all intaglio printing is not gravure—for exam-
`ple, copperplate printing, which is an intaglio process
`without being considered a gravure _process), developed
`around the same time as Gutenberg was developing relief-
`based printing (the mid-15th century). Intaglio, primarily an
`artist's medium, was essentially a wooden (and soon metal)
`block on which the image to be printed was etched. A thin
`ink was poured into these etched lines or dots, and the paper
`on which the design was to be printed was brought into con-
`tact with the inked image carrier in such a way as to forte
`the paper into the cells where it could pick up the ink. A
`porous substrate allows capillary action to enhance this
`process. Around 1440, the first metal plates began to be
`used, commonly made from copper (hence the term copper-
`plate engraving). Intaglio was used primarily for illustration
`matter and playing cards. Around the same time, Guten-
`berg's letterpress-based printing press was increasing in
`popularity, and the use of intaglio for text was not actively
`pursued, as the intaglio plates were incompatible with the
`relief method of printing. Still, intaglio represented a more
`artistic rather than commercial medium, perhaps best exem-
`plified by the woodcuts and other engravings of German
`artist Albrecht Mixer in the late 15th and early 16th cen-
`turies, as well as engravings by other noted artists such as
`Rembrandt van Rijn and Peter-Paul Rubens.
`In the first half of the 16th century, the invention of
`chemical etching of intaglio plates was a great leap forward
`for the process. Rather than laboriously scrape away the
`metal itself, artists could now simply scrape away a soft
`coating (known as a resist), which would allow the pene-
`tration of an acid only in certain areas, which would then
`etch the copper beneath the coating chemically, Chemical
`etching made the intaglio process even more favored by
`artists, and intaglio printing proved to provide better-
`quality illustrations than did letterpress, so it was not
`uncommon for the text. of a book to be printed using letter-
`press, and illustrated pages to be printed using intaglio, the
`separate pages being collated together after printing. Denis
`Diderot's great and controversial Encyclopedie, published
`
`361
`
`Petitioner - Owens Corning
`Ex. 1012, p. 3 of 10
`
`

`

`Gravure (cid:9)
`
`Imps below Surface
`of heap Carrier
`
`Intaglio printing, in which the image is below the surface
`of the image carrier.
`
`in seventeen volumes of text from 1751 to 1755, was sup-
`plemented by several additional volumes of intaglio illus-
`trations, which served to primarily illustrate various
`manufacturing processes as part of Diderat's extolling of
`the virtues of artisans. (This would be a contributing factor
`in the French Revolution of 1789.) Intaglio-based printing
`was also widely used for the reproduction of sheet music, as
`well as maps, needed more than ever once the New World
`was found and colonized. The invention of the mezzotint
`(an early means of representing shades of gray in copper-
`plate engraving; "mezzotint!' itself literally means, in Ital-
`ian, "halftone") in the 1600s further refined the use of
`intaglio for high-quality pictorial reproduction.
`Following the invention of lithography at the tail-end
`of the 18th century, and its further development in the 19th
`century, the search was on for a means of printing utilizing
`cylinders, rather than flat plates, stones, or locked-up bits
`of type. The one desperate need of any printing press is, as
`its name indicates, pressure. It is easier and less laborious
`to produce suitable and uniform printing pressure in the
`nip of two cylinders than over the surface of a flat plate, but
`the question was how to accomplish it; a litho stone could
`not be bent into a cylinder, the individual letters, or even
`lines, of type were impractical for rotary printing, and
`intaglio techniques were not able to keep the ink from
`spilling out of the cells. The development of stereotype
`platemaking eventually solved the problem for letterpress
`printing, and the later use of zinc and aluminum plates
`eventually solved it for lithography. Interestingly, the first
`cylinder-based printing press was a gravure press, origi-
`nally developed for printing on textiles in 1680. The quality
`was most likely not very high, but its primary usage was in
`the printing of calico patterns on cheap clothing. In 1783,
`British textile printer Thomas Bell patented a rotary
`intaglio press for use in higher-quality textile printing. His
`patent drawings show a system very much like that still in
`
`362
`
`Gravure
`
`use in gravure printing today, but far non-textile printing,
`the idea of a rotary press languished.
`The invention of photography in the 1820s and 1830s
`resulted in the search for a means of transferring a photo-
`graphic image to an intaglio plate. William Henry Fox Tal-
`bot devoted himself to the search for photoengraving
`materials and techniques, Using gelatin-based coatings for
`metal plates, he was able to achieve photographic etching
`initially for only line art, but eventually he devised formu-
`lations that would enable the selective variation of image
`density, which would print at varying shades. Fox Talbot
`soon hit upon the halftone screen, which broke up continu-
`ous images into very small, discrete dots that could be var-
`ied in size and shade of gray. This was the breakthrough
`photoengravers (and printers everywhere) needed. Letter-
`press and lithographic platemaking were the direct benefi-
`ciaries of this process, however. The intaglio process was
`desired by most people for little more than fine art repro-
`ductions and illustration material.
`The problem for gravure still remained: how to produce
`a photographic coating for a cylinder that could be used for
`etching. The English engraver J.W. Swan solved the prob-
`lem in the early 1860s with a carbon tissue, which was a
`gelatin resist coating on a light-sensitive material applied
`to the surface of paper. After exposure, the paper could be
`removed, and the exposed coating applied to another sur-
`face, such as a metal plate—or a cylinder.
`Thus, all the disparate elements needed for modern
`gravure printing existed, and it remained far someone to
`put them all together. That someone was Karel Klic (in•
`German spelled Karl Klietsch), from Bohemia (now the
`Czech Republic). Combining Bell's rotary intaglio textile
`press, Fox Talbot's halftone screen process, and Swan's car-
`bon tissue coating, Klic developed the first gravure printing
`press. Still used exclusively in the printing of textiles, how-
`ever, Kilo made his way to England and teamed up with
`Samuel Fawcett, an engraver at Story Brothers and Com-
`pany, a textile printing company. In the early 1890s, they
`developed new techniques for photoengraving, and began
`commercial printing of intaglio art prints, conducted with
`such secrecy that company employees wore not allowed to
`venture into rooms other than those they were assigned to.,
`lest they become exposed to all of the various parts of the
`process. A bit paranoid, perhaps, but the company—under
`the name of Rembrandt Intaglio Printing Company—held
`a monopoly on the process for over a decade. In 1903, ar.
`employee of Klic's came to the United States and revealed
`nes process. The jig was up.
`Meanwhile, in 1860, a French publisher named Augusto
`Godchaux developed a rotogravure press that printed on
`rolls (or webs) of paper, a design very similar to modern
`rotogravure press designs. In the early 1900s, gravure
`presses began turning up in the United States, and the
`New York Times in 1913 was the first to print rotogravure
`newspaper supplements. Other newspapers began to take
`notice of the high-quality reproduction of photographs the
`new system afforded. (Today, most Sunday newspaper sup-
`
`Petitioner - Owens Corning
`Ex. 1012, p. 4 of 10
`
`

`

`Highlight
`Aran
`
`Middleton/a
`Area
`
`Shadow
`Area
`
` Unexposed
`
`5.muts4on
`
`s. ExP"114
`Hardened (cid:9)
`Emulsion
`
`t
`Paper
`BackMg
`
`Area (cid:9)
`
`Mlddtetone (cid:9)
`Area (cid:9)
`
`Shadow
`Area
`
`hardened / (cid:9)
`iEnwision /
`
`Gravure Cylinder (cid:9)
`
`Paper
`Backing
`
`Unexposed
`Emulsion
`
`
`
`Gravure
`
`Gravure Cylinder. A gravure press moot often prints
`from a gravure cylinder, which comprises a steel base, that
`can either be a sleeve cylinder or a shaft cylinder. A
`sleeve cylinder requires a shaft to be attached when it is
`mounted on the press, or when it is mounted in the engrav-
`ing mechanism. The inaccuracies inherent in the fitting of
`a separate shaft have brought about the development of a
`shaft cylinder, which comes with shafts already mounted,
`and they are the dominant gravure cylinder bases currently
`utilized. Altireinum bases have be devised to hopefully
`replace steel, especially in. presses used in the printing of
`packaging, but although they are lighter they are also
`harder to electroplate. Newer plastic cylinder bases are
`being developed that are much lighter than metal bases,
`and contain special surface coatings (most of which are pro-
`prietary) that facilitate electroplating.
`
`—1 (cid:9)f
`
`Middletona (cid:9)
`Area (cid:9)
`
`Shadow
`Area
`1- (cid:9)
`1—
`/ ge / / /
`
`
`/ s (cid:9)
`
`Exposed (cid:9)
`liardened / (cid:9)
`',Emulsion i
`..
`
`Highlight (cid:9)
`Area (cid:9)
`
`—1. (cid:9)
`
`
`.0. (cid:9)
`
`Gravure Cylinder
`c principle of the carbon tissue resist. After exposure to a
`tinuous-tone positive (A) highlight areas are more highly
`osed and thus produce a thicker and harder emulsion
`n do shadow areas. After the exposed resist is attached to
`gravure cylinder (B), an etchant is applied, which eats
`_rough varying thicknesses of emulsion (C).
`
`ements—such as the New York Times Magazine, Parade,
`:3A Weekend, and other color supplements across the
`ntry—are printed on rotogravure presses.) In the
`30s, gravure presses began to be used in the printing of
`kaging; a single-color gravure press in 1933 was set up
`print Tootsie Roll wrappers. In 1938, multicolor gravure
`sees were used for the printing of Jell-O boxes. These so-
`ed "Jell-O presses" were the largest and fastest yet
`igned; together, they were capable of printing up to
`,000 cartons an hour and were in use until 1987.
`Modern advances in engraving technology have made
`vure printing a high-quality printing operation. The
`sense of producing and imaging the gravure cylinders,
`ever, still continues to make gravure printing an
`ensive process, and gravure is rarely used economically
`print-runs of under 200,000 or so. An advantage of
`vure printing, though, is the relative simplicity of the
`as, which does not require the intricate series of ink and
`opening rollers that a lithographic press requires.
`
`GRAVURE PRESSES
`The gravure printing press has several basic elements:
`vure cylinder, ink fountain, impression roller, and sub-
`te control.
`
`Mode
`
`The principle of electroplating. The gravure cylinder base is
`given a negative charge and thus arts as a cathode. A cop-
`per anode is given a positive charge. Copper ions are thus
`forced into the solution, where—being positively charged—
`they bond with the negatively charged cylinder.
`
`To the cylinder base is electroplated a layer of copper,
`which has historically been—and continues to be—the
`dominant surface material for gravure cylinders—and is
`commonly electroplated to the base utilizing a sulfuric-acid
`electrolyte. On top of the copper, after engraving, is plated
`a thin layer of chrome, which is applied to protect the
`etched copper surface from the abrasion of the doctor blade
`during printing. After print runs, the cylinder needs to be
`resurfaced. (See Electroplating.)
`The copper surface of the cylinder, prior to printing, is
`etched or engraved. A particular image printed in gravure
`is essentially a collection of many tiny cells that are etched
`with varying depths (darker regions of a print utilize
`deeper cells that can hold more ink, while lighter regions
`utilize shallower cells that hold less ink). This is why
`gravure-printed typo can look fuzzy when examined under
`magnification. But due to this printing mechanism, gravure
`can print halftones extremely well. Before the development
`of electromechanical engraving in the 1960s, most
`gravure cylinder etching was performed photochemically,
`using carbon tissue resist coatings and ferric chloride
`etchants to chemically etch the image areas. Now, the art-
`work to be engraved is often placed before an optical scan-
`ning device, which uses photodiodes to receive the image,
`and the image is transformed into digital data, which is
`
`363
`
`Petitioner - Owens Corning
`Ex. 1012, p. 5 of 10
`
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`

`

`Gravure (cid:9)
`
`then used to drive an engraving head (typically a diamond
`stylus), which can produce as many as 5,000 cells per sec-
`ond. New developments in direct computer-to-engraving-
`head imaging are removing the need for a film positive from
`which to obtain the information to drive the engraving
`head.
`One particular consideration with the gravure cylinder
`is ensuring that it is as close to perfectly round as possible
`(and that the circumference of the cylinder is large enough
`to carry the image to be printed). Total indicated runout
`(TIR) is used to indicate the roundness of the cylinder, and
`gravure cylinders are manufactured—and need to be
`kept—within strict tolerances. (See Gravure Cylinder
`and Gravure Engraving.)
`
`Ink Fountain. The inking system for a gravure press is
`far less complex than that used for offset lithography,
`The gravure cylinder is partially submerged in a large pan
`of thin, highly fluid ink. (Ink is pumped into the pan as
`needed from a sump, typically located below the fountain
`pan.) As the cylinder rotates in the ink, its surface becomes
`covered with ink, and the cells fill. A thin, flexible steel doc-
`tor blade, either alone or in tandem with other pre-wiping
`devices, scrapes the excess ink from the surface of the cylin-
`der before the inked cella contact the substrate. Some
`gravure inking fountains utilize a fountain roller, a cloth-
`covered railer that is partially submerged in the ink foun-
`tain and that contacts the surface of the gravure cylinder.
`In some configurations, ink is sprayed onto the surface of
`the cylinder by a nozzle. (See Inking System: Gravure.)
`
`Gravure
`
`action transfers the ink to the substrate. The pressure
`exerted on the substrate as it passes though the nip can be
`adjusted. The impression roller typically has a smaller
`diameter than the gravure cylinder and consequently
`rotates at a faster rate. However, in the nip between the
`two cylinders, the rubber is deformed slightly by the pres-
`sure of impression roller against the gravure cylinder.
`Faster press speeds in recent years, however, have resulted
`in excessive heat buildup in smaller impression rollers.
`Consequently, many presses now utilize larger-diameter
`rollers, which also have the added advantage of reducing
`stress on the web, as the increased size of the nip results in
`the same total amount of pressure being applied but over a
`larger surface area. Too large an impression roller, how-
`ever, can cause printing defects, as the substrate remains
`in the nip for a longer period of time. As with the gravure
`cylinder itself, the TIR of an impression roller should be
`carefully monitored. The excessive friction caused during
`web gravure printing can also result in high static charge
`buildup. These charges can exceed 25,000 volts and can
`cause such printing problems as whiskering, or health
`hazards such as severe electrocution. A related phenome-
`non, but one that is induced deliberately and that has pos-
`itive effects, is known as electrostatic assist, in which the
`impression roller is given a static charge that attracts the
`droplets of ink from the gravure cells to the substrate and
`helps to more completely transfer ink and reduce the occur-
`rence and severity of such problems as snowflahing. (See
`Impression Roller.)
`
`Power Transfer
`4----- Roller
`
`Charged Impression
`Roller \
`
`Substrate
`
`Grevuro
`Cyl!nder
`
`Basic gravure inking system,
`
`The principle of the electrostatic assist (ESA).
`
`Impression Roller. The gravure impression cylinder, or
`impression roller, is a hard cylinder covered with a syn-
`thetic rubber lying directly above the gravure cylinder. The
`purpose of the impression roller is to exert pressure on the
`substrate passing through the nip between the impression
`roller and gravure cylinder. This forces the substrate par-
`tially into the cells on the gravure cylinder, where capillary
`
`Substrate Control. The feeding systems used to control
`the movement of the web of paper (or other material)
`through the press vary by press. Since gravure is used for a
`wide variety of different types of substrates, all of which
`contribute various feeding problems, web handling equip-
`ment comes in a number of different configurations. Plas-
`tics, films, and other nonpaper substances are often
`
`364
`
`Petitioner - Owens Corning
`Ex. 1012, p. 6 of 10
`
`

`

`Gravure (cid:9)
`
`Gravure
`
`heat-sensitive, nonabsorbent, and easily stretched beyond
`their ability to return to their original dimensions. Paper,
`on the other hand, is more resistant to stretching, is less
`heat-sensitive, and is more absorbent. But it is also bulkier
`and, more often than not, needs to be printed an both sides
`simultaneously. Consequently, web handling units for
`packaging films requires a more tension-controlled path,
`less heat for drying and, consequently, a faster-drying ink.
`Immediately after the printing unit, it is not uncommon for
`the web's drying path to be a vertical one; the web travels
`vertically up to a fixed distance, allowing it time to dry—
`expedited by hot-air dryers—and either out to the finishing
`section of the press, or back down again, depending upon
`how much drying time is specifically required. It has
`become more common for drying paths to be varied accord-
`ing to the job by add-on modules that provide more or less
`drying space. This has become increasingly necessary on
`higher-speed presses; modern packaging presses print at
`speeds of up to 1,000 ft./min., while publication presses can
`print at speeds exceeding 3,000 ft./min.
`The web roll is placed an a reel stand, which has
`developed over the years from simply holding one roll at a
`time (which required press stoppage when the roll ran out
`and needed to be replaced) to a two-roll stand (which
`required a good deal of operator skill to switch to the new
`roll when the first one ran out) to fully automated, two-roll
`unwinding systems. Most webs—either paper or packag-
`ing—tend to have 3- or 6-in.-diameter cores, made primar-
`ily out of cardboard, with plastic and metal cores becoming
`more popular, as they tend to retain their roundness more
`easily. (Cores that are out-of-round will result in the roll
`' unwinding with a bump, which will cause feeding problems
`and perhaps web breaks.) The most common type of reel
`stand consists of two metal arms, one fixed, the other move-
`able. Attached to each is a cone that fits into the core of the
`roll. The roll is mounted first on the fixed arm, then the sec-
`ond is moved in to engage the other side and hold it firmly.
`The centering of the roll far travel into the press can be per-
`formed by moving the arms in or out, as may be necessary.
`, Some reel stands also make use of an earlier configuration
`involving a metal bar that runs through the center of the
`.•roll. Many configurations involve two unwind stands at the
`end of a long central arm, the whole assembly looking
`rather like a see-saw. One bask problem that needs to be
`accounted for is, as was mentioned, the out-of-roundness of
`the core, which always exists to some degree. If kept within
`certain tolerances, it is acceptable, but the reel stand must
`be sufficiently sturdy to guard against any vibration caused
`by the nonconcentric core disrupting the printing units of
`• the press. When one roll runs out, the new one must imme-
`, diately and carefully be spliced to it, the point being to
`avoid having to stop the press. Often, this system is auto-
`mated, but it still requires careful preparation on the part
`of the press operator. The appropriate amount of web ten-
`- sion is carefully regulated by running the web around a
`dancing roll, a roller connected to an air cylinder that can
`be adjusted to apply the appropriate amount of force to the
`
`web. Newer systems carefully measure the diameter of the
`roll repeatedly as it is unwinding (to account of any eccen-
`tricities or out-of-roundness), either by ultrasound sensors
`or other means, and automatically adjust the speed of the
`motor driving the unwinding reel.
`The final portion of the press just prior to the printing
`unit is known as the in feed tension unit, which is little
`more than two rollers, the nip of which the web passes
`through to reach the printing unit. This nip, regulated by a
`mechanism similar to a dancing roll, ensures that the web
`tension beyond it is consistent, regardless of what is hap-
`pening to the web prior to reaching the nip. This tendency
`to isolate regions of web tension ensure that any anomalies
`are dealt with before the printing unit. (See also Web Off-
`set Lithography: Feeding Section.)
`
`SH:Eurpro) GRAVURE
`Most of the gravure presses in operation are web-fed presses,
`but occasional sheetfed gravure work is done, such as for
`printing proofs, fine art posters and prints, cartons, and
`other high-quality work for which sheetfed offset lithogra-
`phy is inappropriate (such as the printing of metallic inks
`that are incompatible with offset press chemistry).
`Sheared gravure presses consist of a pile table on which
`the sheets are stacked and. are fed into the press, through
`the printing unit (a standard gravure cylinder-impression
`roller-doctor blade arrangement, with the cylinder typically
`inked by a fountain roller), transported by a series of
`transfer cylinders, over several drying nozzles, and
`finally to the delivery pile. Some configurations of
`sheetfed gravure presses also replace the gravure cylinder
`with a flat gravure plate.
`A variety of intaglio plates are used for high-quality,
`specialty printing such as bank notes, postage stamps,
`money, securities, and other such documents. These can
`either be sheetfed or web-fed, and are more commonly
`known as copperplate printing. See Copperplate Printing.
`
`OFFSET GRAVURE
`Some substrates (such as those with irregular surfaces) are
`printed by a process called offset gravure, or indirect
`gravure, which comprises the standard gravure printing
`unit, except that the image is first transferred from the
`gravure cylinder to a rubber-covered transfer roller which
`first receives the image from the gravure cylinder, then
`transfers it to the substrate passing between the transfer
`roller and the impression roller. (This is based on essen-
`tially the same principle as offset lithography.) Products
`printed by this method include decorated metals and
`woods, and other types of irregular surfaces. The resilience
`of the rubber image-carrying blanket makes printing on
`hard surfaces such as these much easier. A variety of offset
`gravure takes place on a flexographic press, where the
`Anilox roller of the flexo press is replaced by a gravure
`cylinder. The gravure cylinder transfers the image to a rub-
`ber blanket, which has been mounted to the flexo plate
`cylinder. The blanket then transfers the image to the sub-
`
`365
`
`Petitioner - Owens Corning
`Ex. 1012, p. 7 of 10
`
`

`

`Gravure
`
`strata. This is known as flex° gravure and is used to print
`high-quality packaging, advertising, and other materials
`commonly printed by traditional flexographic means, but
`with the increased quality of gravure printing. Gravure
`units are also occasionally added to regular flexographic
`presses, for the overprinting of various elements, such as
`prices, store addresses, and other design elements that
`need to be changed several times over the course of a print
`run, on products whose other elements are printed by tra-
`ditional flexography.
`Gravure, like other printing processes, has specific ink
`requirements that produce the best results, specifically,
`highly fluid liquid inks with volatile solvents. (See Ink:
`Printing Requirements: Gravure.) Gravure presses also
`require paper substrates with certain characteristics to pro-
`duce the best results. (See Paper and Papermahing:
`Printing Requirements: Gravure.) Gravure is also well-
`suited for printing on a host of other types of substrates,
`such as foils, plastics, etc. When used on plastic packaging,
`most gravure presses require the use of fast-drying solvents.
`
`Gravure Association of America (GAM
`An organization dedicated to the advancement and dissem-
`ination of information about the gravure printing industry
`and related industries. GAA. is also involved in the produc-
`tion of educational materials, textbooks, and other materi-
`als related to gravure printing. They also perform valuable
`research and publish recommended guidelines and techni-
`cal specifications for printers and manufacturers.
`
`Gravure Cylinder
`The engraved image carrier used in gravure printing.
`Unlike letterpress or lithographic printing processes
`(which use raised and flat printing surfaces, respectively)
`gravure prints from cells or depressions etched in a metal
`cylinder that are filled with ink and transferred to the
`substrate.
`A gravure cylinder comprises a (typically) steel cylin-
`der base, or an underlying metal structure that supports
`the engraved image-carrying layer. The two primary types
`of cylinder bases are sleeve cylinders and shaft cylin-
`ders. A sleeve cylinder differs from a shaft cylinder in that
`it needs to have shafts attached prior to installing it on the
`press, whereas a shaft cylinder, as its name indicates,
`comes with shafts attached, The disadvantages of a sleeve
`cylinder include the fact that different shafts (with their
`own peculiar inaccuracies) are used during different stages
`of production—engraving, preparing, and printing—which
`create inaccuracies in the engraved image and, ultimately,
`in the printed image. Shaft cylinders, utilizing the same
`shafts at each stage of production, are remarkably accurate
`and, not surprisingly, are the most widely used cylinder
`bases. Although steel is the most-often used material for
`cylinder bases, aluminum bases are utilized occasionally,
`primarily for their light weight (making shipping less costly
`and handling easier), but aluminum is more difficult to
`electroplate the image-carrying copper to and is less resis-
`
`366
`
`Gray
`
`A
`
`Two varieties of gravure cylinder: sleeve (A) and shaft
`
`tent to wear than steel. New plastic materials are
`starting to be utilized in gravure cylinder manufac
`which can be modified to facilitate electroplating, and
`also much lighter and less expensive than conventi
`steel, As the cylinder is for the most part hollow, de
`tion needs to be taken into consideration. Deflection
`defined as the deformation of the circumference of
`cylinder (also referred to as out-of-roundness) due to
`pressure exerted by the impression roller during p
`ing. Wider cylinders are more prone to deflection
`shorter ones, and frequently the walls of the cylinder
`reinforced to increase structural rigidity. Cylinders
`become out-of-round produce a variety of printing de
`Defects are also caused by cylinders that are not perf
`balanced, or in which the center of gravity does not
`along its rotational axis. The result of an imbalanced cyl
`der is the generation of vibrations as it rotates. Holes
`metal plugs are added to various portions of the cylinder
`a means of redistributing the mass and bringing it
`into balance.
`Onto the gravure cylinder base is electroplated a la
`of capper, into which the image will be etched. Copper
`been used as the image-carrying layer since the ear
`days of intaglio printing, and it provides the highest de
`of predictable, structural, and functional results. It is
`enough to electroplate and to engrave, and it also %
`stands increased printing pressure without causing br
`downs in the walls of the cells comprising the image.
`Electroplating.) After the copper is plated to the cyli
`base, the copperplated surface is ground down to a red
`size, if necessary. Polishing and finishing operations ens
`that inaccuracies inherent in the copperplating proced
`are compensated for.
`After copperplating and polishing, the gravure cylindat
`is engraved in one of the several different engraving m
`ods in use today. Gravure engraving etches the image
`the copper surface, the image comprising many tiny c
`the distribution and depth of which determine the li
`nessidarkness of a particular image area. The unengra
`portions of a gravure cylinder are known collectively as f4
`land area. (See Gravure Engraving.)
`
`Petitioner - Owens Corning
`Ex. 1012, p. 8 of 10
`
`

`

`Gravure
`
`To impart an added degree of protection and lower the
`coefficient of friction (thus increasing the run length of the
`cylinder) a thin (about 0,00023 in.) layer of chrome is elec-
`troplated on top of the engraved cylinder. Chrome polishing
`is the final stage of gravure cylinder production. A crucial
`measurement prior to printing is the total i