Flexographic printing is a printing method that uses flexible photopolymer or rubber plates. Ink is transferred to the raised areas of the plate by a roller whose surface is covered with tiny cells; the plate then prints the ink onto the film. A separate print unit is used for each colour.
Because the plates are relatively easy to prepare and adapt to different film types, flexographic printing is widespread in bag production. It is often chosen for designs with logos, flat colour areas and text. For jobs that need very fine detail and wide tonal gradations, methods such as rotogravure are also considered. Whichever method is chosen, the film surface must have undergone corona treatment before printing.