- Laminate
- Lino Cut
- Thermography
- Digital Inkjet
- Glossary / Key-Terms
Print Process
Printing is a collective term used to describe the various techniques used to apply ink to stock. Some of these techniques include: offset lithography, silkscreen printing, letterpress, gravure, ink-jet, lino-cut and flexography amongst several other common techniques used in commercial printing. Each method has its own variables such as printing speed, available range of colour, reliability, colour range, capacity, costs, finishes and more. Different printing methods also have to be considered depending on the stock, for example to print into a golf ball you couldn't lithographically print it, a pad print is the more obvious soluion. Design for print is very much about the feel of a product, so for example you could laser print a legible flyer, but it wouldn't have the same type indentation and texture as a letterpress print.
The printing process is often overlooked when a job is being designed for print, the designer should very much take into account the printing method in mind, on what stock and what limitations and creative opportunities are presented. This allows the visuals to optimise and manage factors such as printing speed and costs.
This book will look at a variety of print processes and a basic introduction on how they're work and where they're used so in the future you'll know what print process is suited for your desired finish.
<examples of various prints>
Lithographic
Lithographic printing is a process where separations are exposed to separate metal plates and transferred (offset) via a rubber blanket to the stock to produce the required design.
Lithography is basically printing in layers of CMYK+Spot on a conveyor belt, it is high speed and high volume and produces consistent industry standard results. Each station along the litho printing press has a different ink. Paper is sheet fed which makes the process even quicker.
Halftones - Prints are a series of halftones at different angles, these halftone dots replicate photographic tones in the print process. Once printed and layered, these dots look like a full colour image to the naked eye. These screen angles as they're called are separated into colours, CMYK. Specials don't require screen angles, they're ready to go as they are and don't need to mix with other colours to produce the right colour, specials print flat with no halftone dots.
Below are examples of a Monotone print, which is made up of tiny dots, a duo tone, two screens, a tritone and a quad tone
(left page bottom, pic of litho + Facing page = screen angles/ moire patterns and litho diagram illustration)
Silkscreen printing
Silkscreen printing is a traditional yet still very popular form of printing, often for producing a limited run of pieces such as posters with high value. Silkscreen printing is the process of exposing a design to a silkscreen, similar to how you would expose a separation to a printing plate for lithographic printing. The screen is produced by printing the design onto acetate, making sure the design is completely opaque and light can not pass through the design. The design is then laid on top of a blank screen coated with emulsion. The heat from the exposure basically cooks the emulsion and dries it onto the screen, the areas where the light can't pass through (the design) still has uncooked wet emulsion which simply washes off, so now the screen is made, basically a very reliable and well made stencil to push ink through.
Silk screen printing is basically like industrial printing but slower and by hand, the principles are still the same, printing in layers. The colours you produce are like spot colours, you can ready mix them or you can work with CMYK and print in separations to make full colour photos, all up to you!
<diagram of screen printing>
<facing page, pics of screen printing or a screenprint>
Silkscreen printing is a traditional yet still very popular form of printing, often for producing a limited run of pieces such as posters with high value. Silkscreen printing is the process of exposing a design to a silkscreen, similar to how you would expose a separation to a printing plate for lithographic printing. The screen is produced by printing the design onto acetate, making sure the design is completely opaque and light can not pass through the design. The design is then laid on top of a blank screen coated with emulsion. The heat from the exposure basically cooks the emulsion and dries it onto the screen, the areas where the light can't pass through (the design) still has uncooked wet emulsion which simply washes off, so now the screen is made, basically a very reliable and well made stencil to push ink through.
Silk screen printing is basically like industrial printing but slower and by hand, the principles are still the same, printing in layers. The colours you produce are like spot colours, you can ready mix them or you can work with CMYK and print in separations to make full colour photos, all up to you!
<diagram of screen printing>
<facing page, pics of screen printing or a screenprint>
Letterpress
Letterpress is a pretty self explanatory method of printing and also the first form of commercial printing. Letterpress is a form of relief printing where an inked raised surface is pressed against a stock or substrate. Some letterpress blocks are also made of wood, but the danger with wood is under immense pressure wood can crumble and erode, whereas block metal is solid.
The raised surface that makes the impression is typically blocks of metal type, but photo-engraved plates can also be used. Letterpress is also widely used for embossing, just simply make an impression with high amount of pressure without any ink, the stock has to be prepared for embossing though, not all stock embosses effectively.
The main defect, but also desirable quality of letterpress is the impression is not exactly the same every time, unlike something like lithography, letterpress is inconsistent. Each impression can vary, depending on the stock, pressure, ink coating and so on.
Letterpress is a pretty self explanatory method of printing and also the first form of commercial printing. Letterpress is a form of relief printing where an inked raised surface is pressed against a stock or substrate. Some letterpress blocks are also made of wood, but the danger with wood is under immense pressure wood can crumble and erode, whereas block metal is solid.
The raised surface that makes the impression is typically blocks of metal type, but photo-engraved plates can also be used. Letterpress is also widely used for embossing, just simply make an impression with high amount of pressure without any ink, the stock has to be prepared for embossing though, not all stock embosses effectively.
The main defect, but also desirable quality of letterpress is the impression is not exactly the same every time, unlike something like lithography, letterpress is inconsistent. Each impression can vary, depending on the stock, pressure, ink coating and so on.
<Facing page example of letterpress>
Rotogravure
Gravure printing is slightly different from flexography and lithographic printing as the image is etched into the printing plate instead of being a raised image, or chemically treated. The image on the copper plate is made up of etched cells which are filled with ink during the printing process. The depth of the cells varies so the quantity of ink printed onto the substrate varies from the most where the cells are deepest to the least where the cells are few. A squeegee style tool called a "doctor blade" is used to wipe excess ink off the printing plate.
Gravure printing is ideal for high run projects such as magazines while still holding the quality and reliability. Spirit inks are used which dry very quickly without the need of any extra process. Gravure is generally more expensive than litho and higher quality. The downsides of gravure are it is only effective and cost-effective for long runs in excess of 100's of thousands. Correction prints are also expensive as a whole cylinder has to be reproduced.
SPEED.
Flexography
Flexography (often called flexo) is again similar on the surface to lithography and rotagravure but the uses and benefits of flexography printing are different. Flexography uses a flexible relief, it is essentially a modernised version of letterpress on speed. Flexography can print on almost any form of substrate. Flexography is the process of choice for packaging materials, containers, folding cartons, plastic bags, newspapers, wrappers and more.
Flexography has the same inking process as lithography in that it applies process colours in the same order of cyan, magenta, yellow and black.
Flexo has an advantage over lithography in that it can use a wider range of inks, water based rather than oil based inks, and is good at printing on a variety of different materials like plastic, foil, acetate film, brown paper, and other materials used in packaging. Printing press speeds of up to 600 meters per minute (2000 feet per minute) are achieveable now with modern technology high-end printers. For maximum efficiency, the flexo presses produce large rolls of material that are then slit down to their finished size on slitting machines.
Flexography (often called flexo) is again similar on the surface to lithography and rotagravure but the uses and benefits of flexography printing are different. Flexography uses a flexible relief, it is essentially a modernised version of letterpress on speed. Flexography can print on almost any form of substrate. Flexography is the process of choice for packaging materials, containers, folding cartons, plastic bags, newspapers, wrappers and more.
Flexography has the same inking process as lithography in that it applies process colours in the same order of cyan, magenta, yellow and black.
Flexo has an advantage over lithography in that it can use a wider range of inks, water based rather than oil based inks, and is good at printing on a variety of different materials like plastic, foil, acetate film, brown paper, and other materials used in packaging. Printing press speeds of up to 600 meters per minute (2000 feet per minute) are achieveable now with modern technology high-end printers. For maximum efficiency, the flexo presses produce large rolls of material that are then slit down to their finished size on slitting machines.
1. Fountain Roller
The Fountain Roller transfers the ink that is located in the ink pan to the second roller, which is the Anilox Roller.
The Fountain Roller transfers the ink that is located in the ink pan to the second roller, which is the Anilox Roller.
2. Anilox Roller
This is what makes Flexography unique. The Anilox Roller meters the predetermined ink that is transferred for uniform thickness. It has engraved cells that carry a certain capacity of inks that can only be seen with a microscope.
This is what makes Flexography unique. The Anilox Roller meters the predetermined ink that is transferred for uniform thickness. It has engraved cells that carry a certain capacity of inks that can only be seen with a microscope.
3. Plate Cylinder
The Plate Cylinder holds the printing plate, which is soft flexible rubber. Sticky 2-way tape is used to mount the plate to the Plate Cylinder.
The Plate Cylinder holds the printing plate, which is soft flexible rubber. Sticky 2-way tape is used to mount the plate to the Plate Cylinder.
4. Impression Cylinder
The Impression Cylinder applies pressure to the Plate Cylinder, where the image is transferred to the substrate.
The Impression Cylinder applies pressure to the Plate Cylinder, where the image is transferred to the substrate.
Thermography
Thermography is an in-line print finishing process utilised to create raised lettering and shapes on a substrate. Thermographic powder is deposited onto a sheet of paper (from an offset printing press) while the ink is still wet. The thermographic powder then sticks to the wet ink and fuses with the ink when then substrate is passed through a heating process, usually an oven exposed to temperatures of 500 to 700 degrees celsius This process leaves a raised, textures surface. The thermography process can also quite easily be used in letterpress prints.
Thermography printing can also be referred to as the process of applying a material which changes colour upon heat. It is commonly used on wedding invitations, letterheads, business cards, greetings cards, gift wrap, packaging and can also be used to print braille text.
<examples of thermography>
The benefit of lino-cut is the actual lino itself can last for years and decades and produce the same print as it did the first time you used it, the drawbacks are the inconsistency and the preparation time, lino's are usually hand-carved.
Lino-cuts are cut in relief and in reverse, so when printing the image is flipped to the right way round, kind of like an offset process, to create the correct image.
Thermography printing can also be referred to as the process of applying a material which changes colour upon heat. It is commonly used on wedding invitations, letterheads, business cards, greetings cards, gift wrap, packaging and can also be used to print braille text.
<examples of thermography>
Lino-Cut
Lino-cutting is a low volume relief printing process, similar to letterpress but instead of placing shaped movable type on top of a surface to apply to a substrate, the actual surface itself is carved, in this case a lino surface. The lino is carved with special lino cutting tools and then pressed using a specialist press, sometimes even a Gutenberg press to create an impression on the substrate. Just like letterpress, this process is unreliable and no two prints rarely look the same, an effect which is often one of the aesthetic attractions of lino-cut.The benefit of lino-cut is the actual lino itself can last for years and decades and produce the same print as it did the first time you used it, the drawbacks are the inconsistency and the preparation time, lino's are usually hand-carved.
Lino-cuts are cut in relief and in reverse, so when printing the image is flipped to the right way round, kind of like an offset process, to create the correct image.
Digital Print
Digital printing is the most recent development in printing. It works directly from a computer, unlike the other print processes which require some degree of human intervention and preparation, such as preparing inks and preparing plates. It is not often used for mass production due to how long it takes to print and the hassle of replacing ink cartridges. Digital printers print using CMYK colours in separate containers. Spot colours are actually possible but it's very uncommon and impractical, you'd probably need a separate printer for each spot colour, basically making a lithographic process out of digital inkjets which isn't too smart. Digital printers are the printers we're probably most aware of in todays world, you'd be hard pressed to find an office without one.
Inkjets have their benefits, the most prominent probably being the convenience and the ability to produce one-offs cheaply, quickly and effectively. The drawbacks are the print quality is very limited in terms of finish and substrates compared to larger scale commercial printing.
There are two types of digital printers - inkjet and laser. Both inkjet and laser work in CMYK colour modes but apply the ink in very different ways, inkjet works with wet ink applied in varying amounts while the paper is fed through with a roller. The stock passes through the printer once and the printer applies the image is one layer.
Laser jet printers work differently. They use toner which is applied to the paper using a technique involving static electricity which charges atoms positively on the paper and the coloured toner making them stick to the paper. Here is a basic diagram of a laser jet printer:
Digital printing is the most recent development in printing. It works directly from a computer, unlike the other print processes which require some degree of human intervention and preparation, such as preparing inks and preparing plates. It is not often used for mass production due to how long it takes to print and the hassle of replacing ink cartridges. Digital printers print using CMYK colours in separate containers. Spot colours are actually possible but it's very uncommon and impractical, you'd probably need a separate printer for each spot colour, basically making a lithographic process out of digital inkjets which isn't too smart. Digital printers are the printers we're probably most aware of in todays world, you'd be hard pressed to find an office without one.
Inkjets have their benefits, the most prominent probably being the convenience and the ability to produce one-offs cheaply, quickly and effectively. The drawbacks are the print quality is very limited in terms of finish and substrates compared to larger scale commercial printing.
There are two types of digital printers - inkjet and laser. Both inkjet and laser work in CMYK colour modes but apply the ink in very different ways, inkjet works with wet ink applied in varying amounts while the paper is fed through with a roller. The stock passes through the printer once and the printer applies the image is one layer.
Laser jet printers work differently. They use toner which is applied to the paper using a technique involving static electricity which charges atoms positively on the paper and the coloured toner making them stick to the paper. Here is a basic diagram of a laser jet printer:
Glossary
Lithography : Most common form of print, roll-fed paper is put through a sort of conveyor belt of print processes, including CMYK plus extra stations for spot colours and specials. Consistent print quality at high volume
Lino cut - lino pieces are carved and pressed against a substrate to create a relief print
Relief press - raised surfaces which make contact with a stock or substrate to make an image with applied ink
Offset - process of printing in different layers at different station, also refers to offset, or angled screen angles for printing in process colour halftones to create an overall image
Separations - colour separations of a print job, CMYK + spot colours and specified specials such as varnishes
Process colours - colours used in the process of all physical printing, usually refers to cyan, magenta, yellow and black
Spot colours - special ready mixed colours which often come in metallic and flourescents, have a unique colour matching reference such as a Pantone code so can be specified all over the world. Used on logos and branding to always be the same hue and tint.
Thermography - process of applying thermographic powder to a still wet surface and passing through an oven to change colour, shine, or raise a surface
Silkscreen - the screens used for silkscreen printing, image is exposed to a silkcreen, which basically becomes a high quality stencil which is ink is pushed through with a squeegee onto a substrate or stock.
Source:
http://www.facemediagroup.co.uk/?page=what-is-litho-printing
http://www.quickchilli.com/index.php?option=com_content&task=view&id=31&Itemid=54
http://www.headlandprinters.co.uk/litho.html
http://en.wikipedia.org/wiki/Rotogravure
http://www.ehow.com/info_8396132_gravure-printing-methods.html
http://en.wikipedia.org/wiki/Flexography
http://www.frewerbrothers.co.uk/thermography.html
1 comments:
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