Wednesday 29 September 2010

Print Processes- Rotary Printing

There are three types of rotary printing processes:
Offset Lithography
Rotogravure
Flexography
Offset Lithography has been a method of mass producing printed items for over 100 years, the method was designed so the each copy is identical to each other. Lithography is suitable for printed items such as newspapers and magazines and can be produced on a even larger scale using web printing which prints hundreds of prints in seconds. The process works by rolling 4 pieces of sheet metal that have the chosen design inked out on them.

Flexographic printing was developed in the late 19th century and grew in popularity, although in the 1940s the process had to be reduced due to the inks not being suitable for food packaging.

Flexographic printing relies on rotating cylinders to apply the ink and feed the paper through the printing process. In this process the plates on the printing cylinder are plastic or rubber, which are used to transfer the image onto the stock. This process is versatile as it allows you to print onto packaging such as drinks cartons, bottles and crisp packets. The process requires you to print in CMYK so the image passes through 4 separate rollers to produce the finished result.
Rotogravure was developed in the late 19th century and was involved in major production by the 1920s and has been used throughout the world since then.

Rotogravure printing is similar to offset Lithography printing as it involves rotating cylinders acting like a washing mangle in order to print an image on a piece or roll of stock. In Lithographic printing the image is etched on a metal plate then the stock is rolled over the plate, usually the stock is heavier and thicker such as wall paper and floor coverings.

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