the book of printing technology
Asmina shaikh semester 4 | graphic design
Introduction to printing technology
contents
History of printing Methods of pring Conventional methods
Unconventional methods
The printing process Types of originals Colour and printing Scanners Imposition Paper Post press oprations Binding Costing and estimation Field visits and practicals Bibliography
Introduction to printing technology
Introduction to printing technology
HISTORY OF PRINTING The Babylonians used a technology in which seals were pressed into damp clay but the Chinese probably invented the printing technology.They used carved stones for making copies by first sprinkling soot over them and then pressing a paper on it and rubbing it until the ashes came off the stone. The oldest known prints were produced in China about 1200 years ago.They consisted of Buddhist texts and were made using ink blocks and small pieces of paper.
Introduction to printing technology
Around 800 years ago a Chinese printer Pi Sheng first formed Chinese characters out of bits of clay. The small pieces could be reused and were similar to what we now call ‘movable type’. Later type was made out of wood. Stencils was another ancient method of printing. The technique reached its peak in Katazome used on silks for clothes during the Edo period in Japan. Most common uses of stencils was to colour old master prints printed in black and white, usually woodcuts. It was also used to colour playing cards.
Introduction to printing technology
methods of printing Conventional methods of printing The conventional methods of printing need a master to mass produce multiple copies of the original. The following methods are considered as conventional: + Relief printing + Lithography + Intaglio + Screen printing
Introduction to printing technology
RELIEF PRINTING A relief print ia an image created by a print making process where a protruding surface faces the matrix (printing plate or block) are inked, recessed areas are ink free. Paper ia pressed aginst the matrixx and ink from the protruding surfaces is transfered to the paper. relief printing uses three kinds of presses.
platen press A platen press is made up of two flat surfaces called the bed and the platen. The platen provides a smooth backing for the paper or other substrate that is to be printed. The raised plate (image to be printed) is locked onto a flat surface. The plate is inked, the substrate is then placed on another flat surface called the bed and pressed against the inked plate producing the impression.
Introduction to printing technology
The platen and bed carry both the paper and the type form. The press then opens and closes like a clam shell. Platen printing is typically used for short runs such as invitations, name cards, and stationary. Larger platen presses are used for die-cutting and embossing. Some platen presses are arranged with the bed and platen in the vertical plane. The plate is inked with an inking roller that transfers ink from an inking plate to the image carrier. Ink is placed on the inking plate by an ink fountain roller. The platen style press has been widely used in printing small-town newspapers since the late 1800s. The printing area is usually limited to a maximum of 18 inches by 24 inches. These presses are also used to print letterhead, billheads, forms, posters, announcements, and many other types of printed products, as well as for imprinting, embossing, and hot-leaf stamping.
Introduction to printing technology
flatbed cylinder press
Flat-bed cylinder presses use either vertical or horizontal beds. The plate is locked to a bed which passes over an inking roller and then against the substrate. The substrate passes around an impression cylinder on its way from the feed stack to the delivery stack. Another way of describing this is that a single revolution of the cylinder moves over the bed while in a vertical position so that both the bed holding the substrate and cylinder move up and down in a reciprocating motion. Ink is supplied to the plate cylinder by an inking roller and an ink fountain. The presses can print either one or two-color impressions.
Introduction to printing technology
Flat-bed cylinder presses, which operate in a manner similar to the platen press, will print stock as large as 42 inches by 56 inches. Flat-bed cylinder presses operate very slowly, having a production rate of not more than 5,000 impressions per hour. As a result, much of the printing formerly done on this type of press is now done using rotary letterpress or lithography.
Introduction to printing technology
rotary press The rotary press is a printing press in which impressions are curved aound a cylinder so that the printing can be done on long continuous rolls of paper. Rotary drum printing was invented by richard mar ch hoe in 1847 and was improvd by william bullock in 1863. There are two types of rotary letterpresses, sheet-fed and web-fed. Web-fed rotary letterpress presses are used primarily for printing newspapers. These presses are designed to print both sides of the web simultaneously. Typically, they can print up to four pages across the web; however, some of the new presses can print up to six pages across a 90-inch web. Rotary letterpress is also used for long-run commercial, packaging, book, and magazine printing. Sheetfed rotary presses are also declining in use; in fact these sheetfed rotary presses are no longer manufactured.
Introduction to printing technology
methods of relief printing LETTERPRESS Letterpress printing is relief printing of text or image using a press with a ‘type high bed’ printing press and movable type in which a reversed raised surfce is inkedand then pressed into the papaer t obtain a positive right reading print. The first movable type was made in china bu bi sheng out of porcelian in 1040.The first metak movable type was invented in korea in 1230 and in 1439 johannes guttenburg developed european movable type printing. By trial and error guttenburg discovered that an alloy of lead, tin and antimony was the best combination to produce movable types as it did not shrink on cooling.
Introduction to printing technology
Guttenburg is also creadited for the use of oil based inks which was more durable than previously used water based inks which would be dried by oxidation and penetration.The first book he printed using movab;e types was guttenburg’s bible published in 1456 which is 1282 pages long.The biggest advantage of movable type was that it could be used over and over again. Pre press production Letterpress uses type that is raised from the non printing which is achieved by using movable metal type casted in metal(alloy of antimony,tin and lead). The non printing areas are sunken.In traditional letterpress work, letters were assembled into copy and line drawings were etched or engraved into plates and all this was placed or composed on a flat marble stone or within a rigid frame spaced with blocks,tightned up and locked.
Introduction to printing technology
Typesetting Typesetting in itself was a skill and intially done manually. Typesetting operations assemble the type characters into pages. There are a number of methods of typesetting including manual assembly of pieces of metal type (letterpress), mechanical assembly of lines of type, and phototypesetting.Until the 1950s, the majority of typesetting was performed using the linotype machine which produces a “slug� or line of type from molten metal. Similar machines produced single characters of type. Today phototypesetting devices have almost completely replaced manual and mechanical methods of typesetting.
Introduction to printing technology
Phototypesetting devices, first demonstrated in the late nineteenth century, were introduced commercially in the early 1950s. They rapidly overtook the linotype and similar machines in importance. In phototypesetting, individual type characters or symbols are exposed onto photographic film or paper. In early mechanical phototypesetting units, entire fonts of characters were stored as negatives on film. In the later generations of computer-driven phototypesetters, the image is generated electronically, and, in the latest generation of units, a laser is used to project the image onto the photographic film or paper. Phototypesetting produces high contrast, high resolution images ideal for printing purposes.
Introduction to printing technology
Flexography Also known as surface printing flexography is most commonly used for packaging. It is achieved by creating a mirroed master of the required image as a 3d relief in rubber or polymer material. Then measured amount of ink is deposited on the surface of the plate using anilox roll and the print surface is rotated and the ink is transfered o the paper.Fast drying inks which are highly volatile are used in flexography.
Introduction to printing technology
Lithography Lithography was invented in 1976. It is a method of printing on smooth surfaces. It uses a chemical process to create an image. The positive of image id hydrophobic, hence when the plate is introduced to an ink and water mixture, ink adheres to the positive of the image and is tranfered to paper when pressed against paper.
Offset lithography This method of printing depends on photographic process and uses a flexible aluminium or polyester plates. The plates have a rough textured surface and are covered by phoosensitive emulsion.A photographic negative of te desired image is placed in contact with the emulsion and the plate is exposed to ultraviolet light. After development a reverse negative (positive) is obtained.
Introduction to printing technology
Intaglio This method was invented in germany in 1436.A family of print making in which the image is incised into a surface known as aa matrix or a plate.In this method the printing areas are the sunken and non printing areas are raised.Normally copper or zinc plates are used. Incisions are created by etching, engraving, drypoint,aquatint or mezzotint. In intaglio printing the plate is covered with thick layer of ink and te excess is wiped out leaving ink only in incisions. A damp paper is placed on top and then the paper and plate are run through the press , through pressure recesses of t the ink transfers from the recesses of the plate on paper. This method is used for very high quantities (10-15 million copies) and very high quality printing.This method is not considered for printing text as it gives jaggered edges.
Introduction to printing technology
Screen printing Screen printing has its origins in simple stenciling , most notably of the japanese form ( katazome) which used cut banana leaves and inserted ink through the design holes on textiles. Modern screen printing process originated from patents taken out by samuel simon in 1907 in england. Nylon, polyester and wire meshes are used to make the matrix.More the number of threads per inch sharper the image.This method can be used to print on any surface and has maximum ink depth.A light sensitive liquid consisting of a mixture of ammonium bichromate and pva( polyvinyl alcohol).Ythis method can be used to make upto a 100 copies at a time.
Introduction to printing technology
Collotype This method is a planographic process which uses photographic gelatin. This method is used to obtain very high quality black and white or colour continuous tone prints without the use of a screen.
Thermography This method produces glossy raised images by using infrared light.First printed by letterpress using transparent adhesive ink coated with resin and passed under infrared light.
Introduction to printing technology
Die stamping This method gives a raised blind embossed image.
Foil stamping In this method a heated block presses the foil on the paper. Under pressure the foil is cut and pasted on the paper.
Introduction to printing technology
unconventional methods of printing Also known as non impact printing these methods donot need masters to produce multiple copies of the original.They are essentially non conntact processes. It produces a new image everytime for every print. Common non impact printing methods are electrophotography, inkjet printing, thermal images, laser printing,etc.
Electrophotography Also known as electrostatic printing , this technology was invented by chester carton in 1937 at the xerox corporation. It is based on a modified xerographic copier. In this the image is illuminated by a flouroscent light and the reflected image is directed through te lenses on to a electronically charged drum. A resin based powder called the toner is attracted to the image areas and ia transfered to sheets of paper and is fixed (fused) by heat.
Introduction to printing technology
INKJET PRINTING Ink-jet technology creates printed documents with streams of ink drops that are deflected to the substrate based on information in digital files. It does not require an image carrier, or plate, and it does not required equipment like a xerographic device or a printing press. The same information can be printed throughout a print job or variable information can be printed based on the requirements of the application. The main types of ink-jet technologies are continuous jet and drop-on-demand.
Introduction to printing technology
Continuous jet With continuous jet technology, drops of ink are continuously produced and applied to the substrate to produce the image. A pump sends ink drops through a nozzle at the rate of over a million per second which can produce an image of nearly the same quality as a continuous tone image such as a photograph. There are three types of continuous jet technologies: charged drops for printing, uncharged drops for printing, and electronic deflection. Drop-on-demand Drop-on-demand is a type of ink-jet technology in which the ink drops are formed and then applied as a response to a digital signal. There are two types of drop-on-demand printer systems: piezoelectric and thermal ink-jet.
Introduction to printing technology
Laser printing A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. Laser printers employ a xerographic printing process but differ from analog photocopiers in that the image is produced by the direct scanning of a laser beam across the printer’s photoreceptor. The laser printer was invented at xerox in 1969 by researcher Gary Starkweather. A laser beam projects an image of the page to be printed onto an electrically charged rotating drum coated with selenium or, more common in modern printers, organic photoconductors. Photoconductivity removes charge from the areas exposed to light. Dry ink (toner) particles are then electrostatically picked up by the drum’s charged areas. The drum then prints the image onto paper by direct contact and heat, which fuses the ink to the paper.
Introduction to printing technology
Ionography Ionography is also known as "ion deposition" or electron "charge deposition printing". The ionographic process creates an image with the use of an electron cartridge which creates a negative charge on a nonconductive surface. The nonconductive surface consists of a drum with a dielectric surface of aluminum oxide which attracts a magnetic toner. The toner is then fixed to the substrate with a cold fusion process. Ionography uses a static electric charge to draw the toner particles from the drum onto the substrate. A high pressure roller fuses the toner to the substrate. A scraping device removes any excess toner from the drum and an erasing rod removes the latent image from the drum so that the drum will be ready for the next copy.
Introduction to printing technology
Ionography is used only for one color printing because the high pressure cold fusion process can slightly distort the substrate, which means that multiple colors may not line up correctly. It is useful for high volume applications and for variable information printing, which allows for changes in the content of the print application during the press run. Variable applications such as checks, statements, letters, tickets, and tags, are printed with the ionographic process. Applications printed with the ionographic process do not hold up to rough handling as well as applications printed with other processes.
Introduction to printing technology
HOW TO IDENTIFY? Letterpress + Ink squash at the edge of the letter due to to heavy pressure. + Slight indentation on the back of the paper. + High ink intensity
Offset + Impression will be even on both text and halftone. + Solid cours are evenly inked. + Better text reproduction than gravure. Lines and texts are sharp and have clear outlines.
Introduction to printing technology
Gravure + Edges of text will not be sharp. + Text is raterised. Lesser quality than offset printing. + High image quality.
Screen printing + Heavy ink deposition and a slighty raised impression. + High and even ink intensity. + Text is blurry and of low quality compared to offset printing.
Introduction to printing technology
THE PRINTING PROCESS The printing process for any kind of printing is divided into three basic steps:
+ Pre press
+ Press
+ Post press
Introduction to printing technology
PRE PRESS Pre press operations encompass that series of steps during which the idea for a printed image is converted into an image carrier such as a plate ,cylinder or a screen.Pre press operations include composition and typesetting, graphic arts photography, image assembly and image carrier prepapration.
PRESS This refers to the actual process of printing.
POST PRESS This primarily involves the assembly of printed materials and consists of basic oprations like folding, cutting, collating, gathering, binding and packaging.
Introduction to printing technology
All offset presses have three basic units of printig cylinnders- the printing cylinders, the inking cylenders and the dampning unit. The three printng cylinders consist of the the plate cylinder, the blanket cylinder and the impression cylinder. Offset lithography uses a planographic plate i.e. the non printing and the printing areas lie on the same level and are differentiatd by differing physiochemical properties.
Pre press production Before the job can be printed, the document must be converted to film and ‘plates’.Film negatives are created from digital file.Images from the negatives are transferred to printing plates by a process of exposure with UV light. Every colour needs a plate which means that a seprate plate must be made for every colour that is printed.
Introduction to printing technology
There are four ways to make a plate that is fitted on the press from the digital files on the computer:
Computer to imagesetterThis method gives a film output and it follows a process of exposure by uv lights.
Computer to plate (ctp)The plate is made by a machine wich uses pre sensitised plates and exposes the image on the plate using laser lights.The plate is developed and dried in the machine itself . An additional coat of varnish is put on the plate that hardens it and hence more copies can be printed.
Introduction to printing technology
Computer to plate on pressThis process uses DI technology and the plate is on the press machine itself . Since this method doesnt not involve fixing the plate on the machine manually and the plate is exposed after it is fixed on the cylinder it reduces registration problem.This also is used to print more number of copies.
Computer to printThis method uses a rechargeable cylinder (similar to the OPC drum in xerox) which creates a new image for every print hence the cost of printing per copy remains the same. It is a plateless printing process.This is used for digital offset printing.
Introduction to printing technology
Diffrent kinds of plates Diazo plates are coated with organic compounds and are developed with a special solvent. They have a shelf life of about one year. These are used for print runs of about 150,000 impressions. Photopolymer plates are coated with organic compounds which are very inert and abrasion resistant. This makes them last much longer than diazo plates. They are used for print runs of up to 250,000 impressions Silver halide plates use photosensitive coatings similar to photographic film, except that the silver halide emulsions are slower and for color reproduction are coated on anodized aluminum. The processing solutions contain silver which must be recovered with the proper equipment before being discharged to the sewer. Film based silver halide plates are used for single color printing and metal based silver halide plates are used in computer-to-plate systems.
Introduction to printing technology
make ready time This refers to the time that is used to fix plate onto the plate cylinder, set the ink flow and other parameters to obtain the correct print. Earlier the process od controlling the ink flow would be done manually but now it is set automatically. A certain percentage of prints is wasted in this process and is considered while doing the costing of printing.The press has to maintain a constant balance between the force required to move the paper forward and the amount of back pressure thatthe paper allows to remain tight and flat while printing.All these parameters are set during the make ready time and are monitered during the rest of the process.
Introduction to printing technology
The inking process Offset printing works on the basic principle that water and ink donot mix.In the process of printing the plate cylinder is first damped by water (alcohol is now used as it is highly volatile and gives better result) so that the non printing areas which are grease resistant absorb water and then it is inked by the inking unit which is a set of cylinders which pass on the ink from the ink reservoir to the plate cylinder and the water resistant areas(printing areas) absorbs ink. The ink from the plate cylinder is then passed onto to the blanket cylinderthat in turn transfers the image to the paper.The plate itself doesnt come in direct contact with the paper thus the term ‘offset’ lithography. All of this happens at an extremely high speed. After the ink is transfered to the paper , it is slightly damp and the ink is nt fully dried. To set the ink on paper it is passed through a drying unit which dries the paper by either heat or a newer technology uses a setoff powder that is sprayed on the paper so that ink doesnt smudge.
Introduction to printing technology
TYPES OF ORIGINALS LINE ART This type of artwork contains only black and white pixels. They are also known as bi-level images.Tey are drawings containing only flat colours without any tonal values.They are bitmap images with a minimum required resolution of 1200 dpi.
CONTINOUS TONE This type consists of the grey scale or colour images.It is considered that reproduction os glossy pictures is better as they reflect back light into the scanner evenly. CMYK images have lesser colours and rgb images have about 1.67 Million colours more than CMYK images.
Introduction to printing technology
HALFTONE A repographic technique that simulates a continous tone imagery through the use of equally spaced dots of varying sizes. The idea of halftone printing originates from William Fox Tablot. In the early 1850’s he suggested the use of photographic screens or veils. The halftone process reduces visual reproductions to a binary image that is printed with only one colour of ink. The binary reproductions rely on a basic optical illusion- that these tiny halftone dots are blended into smooth tones by the human eye.Halftones are used to reduce the amount of ink on paper. Halftone reduces the image to half its size hence before converting the image to halftone it must be ensured that the original is of a much higher resolution. Eg. If an image is printed at 150 lpi the scan must be 300 dpi.
Introduction to printing technology
Density It is the measure of the tonal values of the original or printed image measured by a densitometer. It is observed that darker the grey value more is the density.
density range Also known as contrast range it is defined as the difference between the highest and lowest density in the image.
screen ruling Also known as the resolution of the halftone screens, it is measured in lines per inch (lpi) . This is the number of lines of dots in one inch, measured parallel with the screen’s angle.The higher the pixel resolution of the source file, the greater the detail that can be produced. However such an increase requires a corresponding increase in screen ruling.
Introduction to printing technology
Screen angle The screen angle is another common measurement used in printing and is measured in degrees, clockwise from a line running to the left.
Multiple screens and color half toning When different screens are combined a number of distracting visual effects can occur, including edges being overly emphasized, as well as a moire pattern. This problem can be reduced by rotating the screens in relations to each other.
Introduction to printing technology
Traditional screening The two most common methods of creating screens are :
+ Amplitude modulation
+ Frequency modulation
Amplitude modulation This produces regular grade of dots that vary in size. The number of dots per sq unit area remains the same.
Frequency modulation This produces an irregular grade of dots that vary in size and number.
Introduction to printing technology
Colour and printing Additive colours Red, green, blue are considered as additive colours as they combine to give white light. On the other hand, cyan, magenta, yellow are considered as subtractive primary colours as together they give black(absence of white light). Hence rgb and cmy are complementary colours. R + G = Y R + B = M G + B = C
Introduction to printing technology
We see colours as a result of reflection of certain colour of light. Hence, rgb can’t be controlled in print which is done by CMYK. In 4 colour printing, each image is broken into single colour layers i.e, cyan, yellow, magenta, black. The lightness and darkness of colour is altered by the size of the dot in halftone as the printer cannot alter the amount of ink. CMYK primary printing colours cannot produce metalic or flourescent colours. Due to impurities of inks 100% of all three- cyan, magenta and yellow donot give a 100% black but a muddy brown. Hence a black ink is used to give depth.
Introduction to printing technology
Colour Separation Colour separation is done using primary colour filters - red, green, blue. Colour seperation is done to seperate the different layers of colours namely cyan, magenta, yellow and black. To avoid moire pattern, the C,M,Y and K layers must be at angles such that the difference is 30 degrees. The below angles form the rosette patterns. The difference between yellow and magenta is 15 degrees. But yellow being lighter colour, the moire pattern is not so visible.
Introduction to printing technology
Spot colour In offset printing a spot colour is any colour generated by an ink ( pure or mixed) that is printed using a single run. While making a miulticolour print with a spot colour process, every spot colour needs its own lithographic film.Spot colour printing is usually done using readily available inks.
Fake colour A one colour reproduction printed on a coloured sheet which uses the colour of the sheet as a second colour.
Introduction to printing technology
Colour gamut Colour gamut is defined as the range of colours that can be viewed, displayed or printed. A certain range of colours of red, green, blue such as deeper shades of red, green and blue are beyond the CMYK gamut. Hence, if we choose those while printing, they are changed to the nearest CMYK colours. Hence, RGB gamut (1.67 Million colours) is bigger than CMYK gamut.
Introduction to printing technology
Hexachrome This process was invented in 1994.This method provides a wider gamut than CMYK.It includes brighter orange, green, purple and truer skin tones.It is a 6 colour printing process.The file must be in lab mode/ mode.Also reffered as ‘hi fi’ printing. The inks used for this method are laser-powder ink, inkjet-liquid ink, digital offsetpowder/liquid.
Introduction to printing technology
SCANNERS A scanner is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image.The different types of scanners are:
+ Flatbed scanner
+ Drum scanner
Modern scanners typically use a charge-coupled device (ccd) or a contact image sensor (cis) as the image sensor, whereas older drum scanners use a photomultiplier tube as the image sensor. A rotary scanner, used for highspeed document scanning, is another type of drum scanner, using a ccd array instead of a photomultiplier.
Introduction to printing technology
Drum scanners Drum scanners capture image information with photomultiplier tubes (pmt). Reflective and transmissive originals are mounted on an acrylic cylinder, the scanner drum, which rotates at high speed while it passes the object being scanned in front of precision optics that deliver image information to the pmts. While prices of both new and used units have come down over the last decade, they still require a considerable monetary investment when compared to ccd flatbed and film scanners. However, drum scanners remain in demand due to their capacity to produce scans that are superior in resolution, color gradation, and value structure. Also, because drum scanners are capable of resolutions up to 12,000 ppi, their use is generally recommended when a scanned image is going to be enlarged.
Introduction to printing technology
Flatbed scanners A flatbed scanner is usually composed of a glass pane (or platen), under which there is a bright light (often xenon or cold cathode fluorescent) which illuminates the pane, and a moving optical array in ccd scanning. Ccd-type scanners typically contain three rows (arrays) of sensors with red, green, and blue filters. Ccd’s quality is determined by the range of the light density it can register.High end flatbed scanners can read upto 3.8 Density. Images to be scanned are placed face down on the glass, an opaque cover is lowered over it to exclude ambient light, and the sensor array and light source move across the pane, reading the entire area. An image is therefore visible to the detector only because of the light it reflects.
Introduction to printing technology
The process of scanning Scanner settings- these can be changed from the scanner control window. The different modes are used to scan different types of originals.
+ Flatbed reflective- for opaque images
+ Transmissive- for transparent positives
+ Negative- for film negatives
Mode There are two modes available namely the RGB mode (wider gamut) and the CMYK mode (limited gamut).
Introduction to printing technology
Resolution The resolution for scanning can also be changed. A minimum of 300 dpi at 100% size is considered approprite for both greyscale and colour images. Higher resolutions are used when the scanned image needs to be resiized. For line drawings and bitmap images the resolution should be a mininmum of 1200 dpi.
To scan the printed image having halftone,select descreen to avoid image clash or moirĂŠ pattern.It smoothens the image and hence clarity is lost and the image is blurred.
Introduction to printing technology
File formats
Jpeg : Joint Photographic Experts Group
It has various file compression techniques. It is known as lossy format i.E. While compressing some data is permanently omitted from the file, resulting in poor quality images.
Tiff : Tag Image File Format
A popular lossless image format supported by majority of image editing programs.
Giff : Graphic Interchange File Format
It is a lossless image file format,pixels are lost
Eps : Encapsulated Postscript It has a low resolution screen preview.A standard format for drawing, image or complete page layout, allowing it to be placed into ther documents.
Introduction to printing technology
IMPOSITION In prepress, imposition means the arrangement of pages on the press sheet so that when folded the pgaes read consicutively. The arrangement of the pages on the sheet depends on the size of the press sheet and the pages and lastly the folding and binding of the job.
Introduction to printing technology
Imposition depends on the following factors
The type and size of the press Whether the press is sheet fed or web fed and the size of the press sheet.
Method of binding
Design Imposition also depends on the design of the printed pieces. Whether the printing is multicolour, process colour or single colour and whether both sided are printed.Also whether one or several duplicate images are to be reproduces on the same side of the sheet.
The type of paper Whether the image position in relation to grain direction will affect the folding operation.
Introduction to printing technology
Printer’s marks Crop marks Lines printed in the margins of sheet which indicate to the printer and bindery where the finished product should be trimmed.Its also used to show which part of a photo should be used and which should be cropped off.
Registration marks The printed marks that are used to align the colour seperations for printing so that each colour registers with each other.
Bleed marks The term bleed is used for all objects overlapping the border off your document. Two kinds of bleed a bleed can be a full bleed or partial bleed. With a full bleed you have objects running of your document on all sides. With a partial bleed you’ll have a couple of elements running off the document.If the document has objects with bleed the size of the object must be bigger than the required printing area.
Introduction to printing technology
types of impositions ONE SIDE IMPOSITION In this type of imposition the printing plate is used to print only one side of the sheet as it passes through the printing press.
Ganged impostion For verysmall sizes smaller than the smallest size of the paper that can be fed into the press), multiple copies of the same jobs are imposed oe another
JOB A
side grip
JOB B
side grip
job is imposed on the plate of a bigger size.
JOB A JOB B
gripper edge
gripper edge
JOB A
Introduction to printing technology
In this one plate is used to print on one side of the press sheet and a second plate containing different information is then made, the sheets ar turned over, and the sheets are printed on te
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othr side from the second plate.
side grip
Sheetwise imposition
In the process of printing using sheetwise impositoin, the paper
Work and turn In this the gripper edge remains the same and the side rule
gripper edge
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2
changes and the paper is flipped from left to right.
Work and tumble In this the gripper edge change to the other side and the side rule remains the same and the paper is turned.
gripper edge
side grip
is turned to enable printing on the other side using two methods:
Introduction to printing technology
cutting side grip
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2
Signature imposition
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A large single sheet that is frequently passed through a printing press and then folded and trimmed to form
folding
a portion of a book or magazine is called signature imposition.4,8,12,16,24 And 48 page signatures are common.
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side grip
cutting
gripper edge
folding
gripper edge
Work and turn imposition This type of imposition is used when the paper is printed on both sides uing a single plate. In this process the paper is flipped from left to right to print on the other side. Hence the gripperedge remains the same.
Introduction to printing technology
PAPER History of paper Papyrus Papyrus is a thick paper like material produced from the pith of papyrus plants, a wetland sedge that was once abundant in the nile delta in egypt.It was first manufactured in egypt as far as 3rd millenium bc.
Bone Durint the shang(1600-1050 bc) and zhou(1050bc- 256ad) dynasties of ancient china documents were written on bone or bamboo tablets ot bamboo strips were sewn and rolled togetherinto scrolls.
Introduction to printing technology
Wood pulp was first used in 105 ad. The basic process that is follwed in the manufacturing of paper is:
Types of paper Construction/ sugar paper It is a coarse coloured paper available in large sheets. Its texture is slightly rough and has an unfinished surface. Most commonly used in grade school projects.
Inkjet paper This paper is designed for inkjet printers and is identified by its typical weight,,brightness, opacity and smoothness.
Introduction to printing technology
Photopaper This belongs to a category of inkjet paper and is used for reprouction os photographs.It is available in glossy,semi-matte(silk) or matte finishes. Glossy photo paper It is the most popular kind of photopaper and has aa shinny finish Matte photo paper It is less shinny and gives super quality text results. In offset litho and photographic printing, glossy paper gives highest colour density (dmax), therefore the widest colour gamut.
Introduction to printing technology
Printing quality paper Newsprint It is a low cost, low quality and a non archival paper.Sit is made by a mechanical milling process without using chemical processes to remove lignin. It is used to print newspapers and flyers.
Wove paper It is most commonly known as writing paper and has a uniform surface. It is not ribbes or watermarked and is used to print text books.
Bond paper It is a high quality durable writing paper and contains more rag pulp which produces paper stronger than wood pulp.Its weight is more than 50g/m2 .It also contains a watermark.It is used for government bonds, letterheads and in electronic printers.
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Tracing paper It is a translucent paper which is oil and grease resistant but highly impervious to water.
Map litho The top surface of this paper is smooth and is used for books and leaflets.
Offset This paper is rough on both sides and has more rag pulp content . It is considered good for folding.
Duplex board It is box board and is used in cartons.
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Cartridge It is the most expensive paper and has more rag content . It is used for printing certificates and stamp paper.
Chromo It is a one side coated paper.
Art paper This paper has a china clay coating on the porous side and has a smooth finish. It is available in matte and glossy finish.
Mirror coat Also known as cast coat, this paper has a china clay coating in mirror finish on one side.
Cards This paper is thick and is sold in gross [144 sheets], but is also avalaible in packs of 100 sheets.
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paper standards and sizes Paper is sold in two standards
British standard
International (american) standard
International standards 1000 x 1414 mm 917 x 1297 mm 841 x 1189 mm
These include three basic series of sizes namely:
+ A series
+ B series
+ C series
All the three series have a proportion of 1:√2 (width : length)
among the individual series and also between the sizes within the series. The international standard papers are weighed in grams per square meter (gsm).
c
b
A
A seiers - general printing
B series - posters, large format printing
C series - envelopes for a series
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1
A1
A0
A1 √2
A
2
A2
A3
A3 A4
A4
A5 A6
Standard subdivision
Folio division
A7
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British standard In india we still use these standards for paper. The british standard paper is weighed in kgs.
Fullscap - 13.5” X 17”
Denvy - 17.5” X 22.5” Medium - 18” x 23” Royal - 20” x 25” Crown - 15” x 20” Imperial - 22” x 30”
Special sizes
crown = 15” x 20” 15”
Double crown When the smaller side of the paper is multiplied by 2 you get a double crown size of the respective size.
20”
double crown = 30” x 20”
15”
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quad crown = 30” x 40”
Quad
20”
When both sides of the paper is multiplied by 2 you get 4 times the original size known as a quad.
20”
15”
15”
Folio When paper is divided into half on the longer side it is called a folio. 4to
16mo FOLIO
8vo
32 mo
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POST PRESS OPERATIONS The following operations are included in the post press operation:
+ Cutting
+ Folding
+ Collating
+ Gathering
+ Binding
+ Packaging
Introduction to printing technology
Cutting The machine typically used for cutting large web-type substrates into individual pages or sheets is called a guillotine cutter or “paper cutter�. These machines are built in many sizes, capacities, and configurations. In general, however, the cutter consists of a flat bed or table that holds the stack of paper to be cut. At the rear of the cutter the stack of paper rests against the fence or back guide which is adjustable. The fence allows the operator to accurately position the paper for the specified cut. The side guides or walls of the cutter are at exact right angles to the bed. A clamp is lowered into contact with the top of the paper stack to hold the stack in place while it is cut. The cutting blade itself is normally powered by an electric engine operating a hydraulic pump. However, manual lever cutters are also still in use.
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The cutter operator uses a cutting layout to guide the cutting operation. Typically, the layout is one sheet from the printing job that has been ruled to show the location and order of the cuts to be made. Though cutting is generally considered a postpress operation, most lithographic and gravure web presses have integrated cutters as well as equipment to perform related operations such as slicing and perforating.
Introduction to printing technology
Folding Folding largely completes postpress operations for certain products such as simple folded pamphlets. Other products are folded into bunches, known as signatures, of from 16 to 32 pages. Multiple signatures are then assembled and bound into books and magazines.
Knife folding The knife folding system works by striking the paper with a knife between two rollers. This knife is not actually sharp enough to cut through the paper, it simply strikes the paper along the line through which the fold is desired. Many modern folders however, have a combination of both knife and buckle folding mechanisms.
Introduction to printing technology
Introduction to printing technology
Buckle folding Buckle folders work by feeding the paper at high speeds until it hits a stop. The reaction of the paper is to buckle. High friction rollers will then grip the paper and pull it through, that is, the paper is folded by being squeezed between two high friction rollers. The grip of the rollers is caused by the help of rubber or pu. The front edge of the paper went into a so called “pocket�. The rollers press on each other by help of a spring. The distance between the rollers can be set.
Introduction to printing technology
There are 2 types of feeding systems used by folders: The first is flat pile, this is where the paper is placed on a feeding table and each sheet is then transported into the machine by friction or an aircontrolled suction-wheel. The second type is called “round pile�; this involves the sheets being placed onto a belt on a table or rollers, which takes it around the end of the machine and then each sheet is individually pulled into the machine by an air-controlled suction-wheel. The sheets of paper will be separated by help of blowin
Collating Collating refers to the arranging individual sheets in proper order.
Gathering It s the assembling of the signatures of a book in proper sequence.
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BINDING Binding is the fastening of gathered sheets or collated sheets or signatures.It is the process of physically assembling a book from a number of folded or ynfolded sheets of paper.
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wire stitching Centre stitch In saddle binding one or more signatures are fastened along their folded edge of the unit. The term saddle Binding comes from an open signature’s resemblance to an inverted riding saddle. Saddle binding is used extensively for news magazines where wire stitches are placed in the fold of the signatures. Most saddle stitching is performed automatically in-line during the postpress operations. Large manually operated staplers are Used for small printing jobs. Another saddle binding process called smythe sewing is a center sewing process. It is considered to be the highest quality fastening method used today and will produce a book that will lie almost flat.
Introduction to printing technology
Saddle stitched books are constructed with sheets that are printed front and back that represent four pages of a book. The sheets of four pages are stacked with other sheets in the correct page order and then stapled along the fold line or saddle. The stapling is accomplished on equipment that cuts staples from a continuous roll of wire mounted on the machine and inserts them into the paper. Some machines can do the folding and stitching in one operation. Many booklet manufacturers use this multiple task equipment to increase efficiency. Saddle stitched binding can work for volumes up to 128 pages (32 sheets, printed with 2 pages front and back) if the paper stock is thin enough, but it just isn’t practical for anything larger. The larger the quantity of sheets, the greater the problem with a phenomenon called page “creep�.
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Creep refers to the inner sheets sticking out further than those closer to the outside, because of the paper thickness. To compensate for this, the pages are “shingled”, which means that the inner margin, or “gutter”, is increased on the pages working from the inside of the book to the outside.
Another saddle binding process called smythe sewing is a center sewing process. It is considered to be the highest quality fastening method used today and will produce a book that will lie almost flat.
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Side Stitching In side binding, a fastening device is passed at a right angle through a pile of paper. Stapling is an example of a simple form of side binding. The three other types of side binding are mechanical, loose-leaf, and sidesewn binding. Looseleaf bindings generally allow for the removal and addition of pages. This type of binding includes the well known three-ring binder. Side-sewn binding involves drilling an odd number of holes in the binding edge of the unit and then clamping the unit to prevent it from moving. A needle and thread is then passed through each hole proceeding from one end of the book to the other and then back again to the beginning point. This type of stitch is called a buck-stitch. The thread is tied off to finish the process. Both semiautomatic and automatic machines are widely used to perform side-stitching. The main disadvantage of this type of binding is that the book will not lie flat when opened.
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Instead of staples being inserted into the side or saddle of the pages, staples are inserted into the top of the gathered sheets or pages and pressed down vertically until reaching the back side of the booklet. It is often used as a means to bind a larger quantity of sheets together than can be saddle stitched.
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office stationary Adhesive binding Adhesive binding, also known as padding, is the simplest form of binding. It is used for note pads and paperback books, among other products. In the adhesive binding process, a pile of paper is clamped securely together in a press. A liquid glue is then applied with a brush to the binding edge. The glue most commonly used in binding is a water-soluble latex that becomes impervious to water when it dries. For note pads, the glue used is flexible and will easily release an individual sheet of paper when the sheet is pulled away from the binding. Adhesive bindings are also used for paperback books, but these bindings must be strong enough to prevent pages from pulling out during normal use.
Introduction to printing technology
For paperback book binding, a hotmelt glue with much greater adhesive strength than a water-soluble latex is applied. A piece of gauze-like material is inserted into the glue to provide added strength. Some printed applications are padded into tablets or booklets with the use of an adhesive applied to one edge of a group of sheets.Padding techniques are actually a form of binding, but the resulting pad or booklet is not intended to remain permanently bound – the padded edge serves only to keep the sheets together until a sheet is used and then detached from the padded edge. Most of the padded products begin as single sheet items, which are then gathered and padded into various quantities to create note and memo pads, prescription pads, coupon pads, and many other similar applications. The padding compound is usually a type of glue, which dries to a soft or semi-hard consistency. There are various types of glue used, such as varieties applied manually as a cold application and other varieties applied by machine as a hot melt application. Note: your vendor may have limitations on the number of sheets that can be padded as well as the minimum and maximum paper weights that can be manufactured into pads.
Introduction to printing technology
lose leaf binding Perfect binding Perfect binding is often used, and gives a result similar to paperback books. National Geographic is one example of this type. Paperback or soft cover books are also normally bound using perfect binding. They usually consist of various sections with a cover made from heavier paper, glued together at the spine with a strong flexible glue. The sections are roughcut in the back to make them absorb the hot glue. The other three sides are then face trimmed. This is what allows the magazine or paperback book to be opened. Mass market paperbacks (pulp paperbacks) are small (16mo size), cheaply made and often fall apart after much handling or several years. Thermal binding uses a one piece cover with glue down the spine to quickly and easily bind documents without the need for punching. The paper is placed in the cover, heated in a machine (basically a griddle), and when the glue cools, it adheres the paper to the spine. Thermal glue strips can also be purchased separately for individuals that wish to use customized/original covers.
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Spiral binding Spiral binding is the most economical form of mechanical binding when using plastic or metal. It is commonly used for atlases and other publications where it is necessary or desirable to be able to open the publication back on itself without breaking the spine. There are several types but basically it is made by punching holes along the entire length of the spine of the page and winding a wire helix (like a spring) through the holes to provide a fully flexible hinge at the spine. Spiral coil binding uses a number of different hole patterns for binding documents. The most common hole pattern used with this style is 4:1 pitch (4 holes per inch). However, spiral coil spines are also available for use with 3:1 pitch, 5:1 pitch and 0.400-hole patterns.
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Comb Binding Comb Binding uses a 9/16" pitch rectangular hole pattern punched near the bound edge. A curled plastic "comb" is fed through the slits to hold the sheets together. Comb binding allows a book to be disassembled and reassembled by hand without damage. Comb supplies are typically available in a wide range of colors and diameters. The supplies themselves can be re-used or recycled. In the United States, comb binding is often referred to as 19-ring binding because it uses a total of 19 holes along the 11-inch side of a sheet of paper.
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Velo Binding There is only one manufacturer for this type of binding, so it is a trademarked brand name. Security strips are used for the binding of pages and it is most often used for legal documents and publications. The equipment used for this type of binding is expensive. Pages cannot be added or removed unless the security strip is cut. VeloBind is used to permanently rivet pages together using a plastic strip on the front and back of the document. Sheets for the document are punched with a line of holes near the bound edge. A series of pins attached to a plastic strip called a Comb feeds through the holes to the other side and then goes through another plastic strip called the receiving strip. The excess portion of the pins is cut off and the plastic heat-sealed to create a relatively flat bind method. VeloBind provides a more permanent bind than comb-binding, but is primarily used for business and legal presentations and small publications.
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Library binding Library binding is the term used to describe the method of binding serials, and re-binding paperback or hardcover books, for use within libraries. Library binding increases the durability of books, as well as making the materials easier to use. A lower cost and in-house alternative to library binding of paperbacks is the stiffening process.
Sewn Soft Cover Occasionally the pages of a book are attached to paperback or soft covers with the use of strong thread, which is sewn through the pages and cover using special equipment. This binding method is often preferred for technical manuals and textbooks, which may be handled often by a number of people. It is more durable than perfect binding or wire binding where the overuse of a book may cause the binding to fail at a faster rate.
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Self-covers are made from the same material as the body of the printed product. Newspapers are the most common example of a printed product that uses self-covers. Soft covers are made from paper or paper fiber material that is somewhat heavier or more substantial than the paper used for the body of the publication. This type of cover provides only slight protection for the contents. Unlike self-cover, soft covers almost never contain part of the message or text of the publication. A typical example of the soft cover is found on paper-back books. These covers are usually cut flush with the inside pages and attached to the signatures by glue, though they can also be sewn in place.
Introduction to printing technology
Different types of signatures
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Hardcover binding A hardcover, hardbound book has rigid covers and is stitched in the spine. Looking from the top of the spine, the book can be seen to consist of a number of signatures bound together. When the book is opened in the middle of a signature, the binding threads are visible. Signatures of hardcover books are typically octavo (a single sheet folded three times), though they may also be folio, quarto, or 16mo (see Book size). Unusually large and heavy books are sometimes bound with wire. A variation of the hardcover which is more durable is the calf-binding, where the cover is either half or fully clad in leather, usually from a calf. This is also called full-bound or, simply, leather bound. Library inding refers to the hardcover binding of serials and paperback books intended for the rigors of library use. Though many publishers have started to provide “library binding� editions, many libraries elect to purchase paperbacks and have them rebound as hardcover books, resulting in longer life for the material.
Introduction to printing technology
Casebound covers are the rigid covers generally associated with highquality bound books. This method of covering is considerably more complicated than any of the other methods. Signatures are trimmed by a three-knife trimming machine to produce three different lengths of signature. This forms a rounded front (open) edge to give the finished book an attractive appearance and provides a back edge shape that is compatible with that of the cover. A backing is applied by clamping the book in place and splaying or mushrooming out the fastened edges of the signatures. This makes the rounding operation permanent and produces a ridge for the casebound cover.
Introduction to printing technology
Gauze and strips of paper are then glued to the back edge in a process called lining-up. The gauze is known as “crash” and the paper strips are called “backing paper.” These parts are eventually glued to the case for improved strength and stability. Headbands are applied to the head and tail of the book for decorative purposes. The case is made of two pieces of thick board, called binder’s board, that is glued to the covering cloth or leather. The covering material can be printed either before or after gluing by hot-stamping or screen methods. The final step in case binding consists of applying end sheets to attach the case to the body of the book.
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Sewn Case Binding Sewn case binding, also known as “edition binding”, is the most expensive binding method, but is the most durable. It can be used for any book thickness, but the most common thicknesses range from 1/4” up to 3”. A number of steps are required to complete a sewn case bound book, so the process is very automated. A large printed sheet containing 16 or 32 individual book pages, called a signature, is cut apart, folded, and assembled in the correct page order.
Introduction to printing technology
The signature is sewn together with other signatures.Endleave papers, which are usually made of heavier stock than the other pages of the book, are glued to the outside of the first and last signatures. The book is trimmed on three sides. The sewn edge (spine) of the book is coated with glue. The spine of the book is rounded in a machine to allow the cover of the book to function properly when it is attached. A strip of gauze is wrapped around the spine of the book. The cases (covers) that will be used for the book are made from heavy board stock with its grain running parallel to the spine of the book to prevent warping of the cover. The heavy board cases are wrapped with embossed paper, cloth, plastic coated material, leather, or other materials to form the final covering. The book is attached to its hard case/cover on a casing-in machine, which glues the endleave papers to the case.The final step is to insert the book into a hydraulic press to ensure that it dries properly and does not warp.
Introduction to printing technology
COSTING AND ESTIMATIONS
Introduction to printing technology
CASE STUDY 1: specifications: name of jobnumber of coloursfinished sizequantity-
A] paper : [name][size][weight] unfinished sizenumber of jobs per plate
quantity
----------------------------- = total number of sheets number of jobs per plate total number of sheets --------------------------- = total number of reams
500
total number of reams x cost per ream = total cost of paper
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B] positives : unfinished size = [ ] cm x [ ]cm size in sq.cm x cost per sq.cm =cost of positive making
C] plate making : number of colours = number of plate number of plates x cost of one plate = cost of plate making
D] printing : number of plates x number of copies x cost of one colour (per plate, per 100 copies) = printing cost
(includes ink, labour, overheads,etc)
E] cutting, finishing, folding : A+B+C+D+E =total cost +10% (printer’s margin) = final cost final cost
--------------------- = cost per copy number of coipes
Introduction to printing technology
CASE STUDY 2 (for books and booklets) specifications: number of copies of the bookfinished size of the bookinside paper-[name][size][weight] cover-[name][size][weight] inside pages- 1+1 colour (number of pages) cover- 2+0 colour
A] paper : inside paper- [name][size][weight] finished size= [ ]” x[ ]” opensize=[ ]” x[ ]” number of pages per sheet= total number of pages -------------------------------- = number of sheets per book number of pages per sheet
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number of sheets x number of copies= number of sheets for all books number of sheets for all books + 10% (pre press) = total number of sheets total number of sheets --------------------------- = number of reams
500
number of reams x cost per ream = total cost of inside paper
B] paper : cover paper-[name][size][weight] number of copies = [ ]+ 10% (pre press) number of copies --------------------------------- = total number of sheets number of covers per sheet total number of sheets --------------------------------- = total number of packets number of sheets per packet
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number of packets x cost per packet = total cost of cover paper
C] layout and plate making : total number of sheets x 2 (for front and back) = number of plates number of plates (inside paper) x cost per plate = cost of plates for inside pages --------- [1] number of plates (cover pages) x cost per plate = cost of plates for cover pages --------- [2] [1] + [2] = total cost of plate making
D] processing: image setting (positives) total number of pages ---------------------------- = number of positives
2
number of positives x cost per positive = cost of positives of inner pages ------------[3] (inner pages)
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number of positives x cost per positive = cost of positives of cover pages ------------[4] (cover pages) [3] + [4] = total cost of positives
E] printing : number of plates printed x number of copies x cost per colour(plate) = cost of printing ---------[5] (inner pags)
(inner pages)
number of plates printed x number of copies x cost per colour(plate) = cost of printing ---------[6] (cover pags) [5] + [6] = total cost of printing
(cover pages)
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F] post press opereations : number of copies x cost per copy = total cost of post press operations
A + B + C + D + E + F = total cost +10% (printers margin) total cost
--------------------- = cost per book number of copies
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field visits and practicals
Introduction to printing technology
FIELD VISIT On our feild visit to the art-o-print press we got the opportunity to see how printing jobs are done at a large scale and how it is done for mass production. We also got to see the ctp machine. It was fascinating to watch all the processes happen under one roof and also how fast they happen. It gave us an experience of actual industrial printing.
Introduction to printing technology
FIELD VISIT On our visit to a factory where corrugated boxes were made we saw how corrugation is done at a large scale and how die cutting happens. Under one roof, we saw how paper was cut, corrugated, pasted to form 2 ply upto 7ply sheets then die cut and folded and finally wire stitched to form cartons.
Introduction to printing technology
PRACTICALS During the practical in offset printing we made artworks that were then imposed on the plate and exposed pre sensitised plates by using film negatives of hte artwork with UV light. The plate was then clamped on the plate cyinder and prints were taken to set the amount of ink. We saw the progressive prints to obtain the right amount of ink and proper registration of different colours.
Introduction to printing technology
In the practical for screen printing we saw how the screen is made using a light sensitive film by exposing to uv light and then developed by washing . The solution in the printing areas is washed offf and the holes arec leared off the solution where as the solution in the non printing areas hardens and bolcks the holes. The screen is then clamped and ink is transfered to the paper by using the squeeze. We explored by printing on a variety of surfaces. For binding we were exposed to the different binding methods and their relevance to the kind of publications. We did each method by ourselves which gave us indepth understanding in how every method is executed.
Introduction to printing technology
bibliography Class notes wkipedia www.google com www.printingtips.com www.science.jrank.org International Paper Knowledge Centre Special thanks to Bharat Suthar & Tridha Gajjar