Printing process 3

Printing Processes
An Explanation

Saturday, August 29 2009, 1

Photocopying
Xerography


Process

http://content.answers.com/main/content/img/CDE/ELECFOTO.GIF


Applications

• Duplicating documents efﬁciently and cheaply (i.e.
duplicating 500 handouts)
• Xerography has been adapted to eliminate the hand-
inking stage in traditional animation. Animated ﬁlms
produced with this method include 101 Dalmatians
(1961) and The Secret of NIMH (1982)


Advantages

• Cheap
• Quick (~60 pages per minute)
• Allows user to alter size of the page
• Digital photocopiers can collect incremental pages
together (so books can be photocopied without being
sorted afterwords)


Disadvantages
• Finding individual pages to scan wastes time
• Takes up a lot of space
• Its most common use - photocopying textbook pages,
violates copyright and the DMCA
• Older photocopiers use ultraviolet light - which some
say is harmful to health
• Toner produces ozone, volatile organic compounds,
selenium, cadmium sulﬁde, nitrogen oxide and carbon
monoxide


An example of a photocopied sheet
(http://jfk.ci.dallas.tx.us/30/3028-001.gif)

Offset Lithography


Process

1. Plate cylinder is dampened and inked
2. Because of the repulsion of the oil-based ink and water,
the ink is transferred onto the offset cylinder
3. The offset cylinder prints the ink onto the paper.


The process of Offset Lithography
http://en.wikipedia.org/wiki/File:Offset.png


Applications
• Commercial printing
• Business Cards
• Stationary
• Menus
• Brochures
• Posters
• Magazines
• Newspapers


An use of Offset Lithography
http://homepages.which.net/~rex/bourne/photos/newspapers.jpg


Advantages

• Good reproduction quality (esp. photos)
• Cheap - the more you print, the less you pay
• Ability to print on a wide range of papers
• Fast
• Widely available


Disadvantages

• Color variation due to water and ink mixture
• Paper can stretch due to dampening
• Needs to be done in a large factory


Flexography


Process - platemaking
1. A ﬁlm negative is placed over a ﬂexible light-sensitive
polymer, which is then exposed to UV light. The polymer
hardens where the light has passed through, but the rest of
the polymer stays relatively soft.
2. The softer polymer is then washed away by water or
solvent.
3. Other methods to produce the plate: Computer guided
laser-etching and molding.


Process - printing
1. The ﬂexible plate it then wrapped around a plate cylinder.
2. The ink is drawn from the ink tank to the Anilox roller,
whose texture is speciﬁcally designed to retain a small
amount of ink. Excess ink is removed by the ‘doctor blade’.
3. The Anilox roller transfers the ink onto the plate, which
transfers the ink onto the paper which is squashed between
the plate cylinder and impression cylinder.
4. Flexographic inks include: Solvent-based Inks, Water-based
Inks, Electron Beam curing inks and Ultra-Violet curing Inks.


The process of Flexography
http://glossary.ippaper.com/images/graphicsedviser/print/ﬂexo.jpg


Applications
• Brown corrugated boxes
• Flexible packaging (i.e. retail and shopping bags)
• Food and hygiene bags and sacks
• Milk and beverage cartons
• Flexible plastics
• Self adhesive labels
• Disposable cups and containers
• Envelopes
• Wallpaper
• Cheap magazines, Newspapers and Paperback books


An use of Flexography
http://eng.amipak.by/i/photo/page/production/print/print03-big.jpg


Advantages
• Fast
• Relatively cheap to set up
• Can use the same apparatus as letterpress
printing
• Can utilize a wide variety of inks
• Can print on a wide variety of materials


Disadvantages
• Cannot accurately reproduce ﬁne detail
• Color may not be consistent
• Individual presses have to be prepared for
each different print
• Poor shadows
• Impression per print is more limited than
Offset lithography


Gravure
or Rotogravure


Process

1. A image is etched onto the surface of a
metal cylinder.
2. The etched area is ﬁlled with ink.
3. The cylinder is rotated, printing onto the
paper.


The process of Gravure printing
http://www.istc.illinois.edu/info/library_docs/manuals/printing/images/ch8ﬁg10.jpg


Applications

• High quality art and photo books
• Postage stamps and postcards
• Packaging
• Expensive magazines (glossy covers)


An use of Gravure printing
http://www.ashtreelabels.com/images/sleeving/sleeve%20products%201.jpg


Advantages
• Consistent color
• High speed
• Good results on cheap paper
• Very durable printing plate
• Ink dries on evaporation - paper can pass
through multiple machines for color prints
with CMYK


Disadvantages

• High costs of printing plates and cylinders
• Only good for long print runs


Screenprinting


Process
1. A screen is made with a fine, porous fabric
(i.e. silk or polyester) and fitted over a
wooden frame
2. Areas are blocked off with a non-permeable
substance to form a negative
3. The screen is placed above paper or fabric
and ink placed into the mesh via a floodbar,
printing on the paper.


The process of Screenprinting
http://en.wikipedia.org/wiki/File:Silketrykk.svg


Applications

• T-shirts
• Posters
• Plastic and Metal signage
• Point-of-sale displays


An use of Screenprinting
http://handmadetees.com/images/hmt-t-shirt.jpg


Advantages

• Economical for short runs
• Stencils are easy to produce
• Can print on virtually any material


Disadvantages

• Difﬁcult to achieve ﬁne detail
• Low output
• Print requires long drying time
• Has to be done manually


Sources

• Textbook
• Wikipedia
• Google image search
• About.com


Printing process 3

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Printing process 3