Flexo Printing is a form of printing process which utilizes a flexible relief plate. It is essentially a modern version of letterpress, evolved with high speed rotary functionality, which 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 colour). http://www.tongjou.com/flexo-printing/