Printing process 3

Printing ProcessesAn Explanation

1Saturday, August 29 2009,

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 Lithographyhttp://en.wikipedia.org/wiki/File:Offset.png


http://en.wikipedia.org/wiki/File:Offset.png


Applications• Commercial printing

• Business Cards

• Stationary

• Menus

• Brochures

• Posters

• Magazines

• Newspapers


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


http://homepages.which.net/~rex/bourne/photos/newspapers.jpg

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 Flexographyhttp://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 Flexographyhttp://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


Gravureor 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 printinghttp://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 printinghttp://www.ashtreelabels.com/images/sleeving/sleeve%20products%201.jpg


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 Screenprintinghttp://en.wikipedia.org/wiki/File:Silketrykk.svg




Applications

• T-shirts

• Posters

• Plastic and Metal signage

• Point-of-sale displays


An use of Screenprintinghttp://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


Education

Printing process 3