With the advent of readily available non-paper substrates (plastics and foils) in the mid-to-late 1950’s, the requirement for a reliable production speed surface treatment process became apparent. Several different technologies have been tried, but one, corona treatment, has become, by far, the primary surface treatment technology used across the Extrusion and Converting Industries. We will touch on these various technologies, technically describe the need for surface treatment and how it is measured, trace the development of corona treatment as the leading surface treatment method, and detail the current state-of-the-art in equipment, control parameters and applications.