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Flexography(often abbreviated to flexo) is a form of printing process which utilizes a flexible relief plate. It is basically an updated version of letterpress that can be used for printing on almost any type of substrate including plastic, metallic films, cellophane, and paper. It is widely used for printing on the non-porous substrates required for various types of food packaging (it is also well suited for printing large areas of solid color).
The process of flexography was then dubbed “aniline printing,” named for the aniline oil used in the ink, that would be jetted out by the use of Anliox roll. In 1890, the first patented press was built in England by Bibby, Baron and Sons. The water-based ink smeared easily, leading the device to be known as “Bibby’s Folly”. In the early 1900’s, other European presses were developed using rubber printing plates. But by the 1920s, most presses were made in Germany, where the process was called “gummidruck”.
During the early part of the 20th century, the technique was used extensively in food packaging in the United States. However, in the 1940’s, the Food and Drug Administration classified aniline dyes as unsuitable for food packaging. Printing sales plummeted. Individual firms tried using new names for the process, such as “Lustro Printing” and “Transglo Printing,” but met with limited success. Even after the government approved the aniline process, sales continued to decline. Intent on re-popularizing aniline printing by changing its name, Franklin Moss, president of Mosstype Corporation, surveyed the industry in 1951 and received over 200 different name suggestions. In October 1952, the new name was announced; “flexography.”
A flexographic print is made by creating a positive mirrored master of the required image as a 3D relief in a rubber or polymer material. Flexographic plates can be created with analog and digital platemaking processes. The image areas are raised above the non image areas on the rubber or polymer plate. The ink is transferred from the ink roll which is partially immerged in the ink tank. Then it transfers to the anilox roll (or meter roll) whose texture holds a specific amount of ink since it's covered with thousands of small wells or cups that enable it to meter ink to the printing plate in a uniform thickness evenly and quickly (the number of cells per linear inch can vary according to the type of print job and the quality required). To avoid getting a final product with a smudgy or lumpy look it must be ensured that the amount of ink on the printing plate is not excessive. This is achived by using a scraper, called a doctor blade. The doctor blade removes excess ink from anile roller before inking the printing plate. The substrate is finally sandwiched between the plate and the impression cylinder to transfer the image.
Originally geographic printing was basic in quality. Labels requiring high quality have generally been printed using the offset process until recently. In the last few years great advances have been made to the quality of geographic printing presses.
The greatest advances in geographic printing have been in the area of photoplay printing plates, including improvements to the plate material and the method of plate creation.
A positive mirrored master of the required image as a 3D relief in a rubber or polymer material.