Areal structure with uniform thickness from an material, which different from a sheet is so thin, that, that it flexes caused by its own weight. Metallic films same as sheets are produced from a raw block by rolling, plastic films by extrusion and winding through a calendar. Thick plastic films are produced same as sheets by flat extrusion, while thin films are produced by blow extrusion like a tube.
Plastic Films are often plasma treated, for example before printing, glueing or laminating multilayer composites.
Endless films can be plasmatreated by Plasmabeam atmospheric plasma or by low pressure plasma using a roll-to-roll-system.