Have you ever wondered how the printing on plastic, foil, acetate film, brown paper and various other materials used in packaging is done? Flexography or flexographic printing uses flexible printing plates made of rubber or plastic to print on a wide variety of packaging materials. The inked plates with slightly raised images are rotated on a cylinder, which transfers the image to the substrate. Flexo, as flexographic printing is also known, is a high-speed printing process that uses fast drying inks and can print on many types of absorbent and non-absorbent materials. It is very efficient for producing continuous patterns like those in wall papers or gift wraps.
Flexographic printing & Letterpress
Both letterpress and flexographic printing print from a raised image. In its original form letterpress used individual metal characters called types and a mechanical press. The types were combined to for words and sentences and tightly arranged on the flat surface of the press. Then the raised areas were covered with ink. The message was formed when the paper was pressed against the flat metal type. The raised areas of the type are called image areas and the lower areas that receive no ink are called non-image areas.
To speed up the slow procedure of pressing flat areas together, the printing press evolved from printing on a flat surface only to using a rolling cylinder. The type moved back and forth from inking rollers to an impression cylinder that held the material to be printed upon. As demand increased, inked type was phased out and inked plates came into use. Rotary letterpress prints from a molded or etched plate.
Flexographic printing uses flexible printing plates wrapped around rotating cylinders. The plate is usually made of natural or synthetic rubber or a photosensitive plastic material called photopolymer. It is usually attached to the cylinder with double sided sticky tape.
Early flexographic inks contained dyes made from aniline oil extracted from the indigo plant. These dyes were dissolved in spirits, making a quick drying ink. Flexible plates, quick-drying ink and the ability to print on a wide variety of material made flexographic printing an ideal option for the packaging industry.
However, it was the invention of cellophane in 1930 that really gave flexographic its current premier status in the print industry. This clean nonabsorbent film could not be printed upon by any other method except flexography’s quick dying ink. With the introduction of polyethylene in the 50s, there was no stopping the rise of flexographic printing.
A tiny hiccup did occur however, when the food & beverages industry believed that aniline oil was harmful to food. The FDA’s green signal in 1949 helped flexographic printing regain its popularity. However, some food manufacturers wanted nothing to do with the tainted reputation of ‘aniline’ printing. Concerned about the image of the industry, packaging representatives decided to search for a new name. In 1952, the term "flexography" was born. It quickly gained worldwide popularity, and the process rapidly expanded.
From its early rise in the 40s, flexographic printing has grown into a multi billion dollar segment of the packaging and printing industry. To fully understand and appreciate the scope of flexographic printing one only needs to visit any supermarket and look around at the shelves filled with countless examples of flexographic printing and what it can do.
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