Method of forming a surface protector with an expansible pocket

Abstract From the Canadian patent

Abstract of the Disclosure, A method of forming a selectively expansible pocket or bulge in a thin plastic sheet to facilitate the use of the sheet as a surface protector or shield includes the step of applying oppositely directed forces to the sheet in a plurality of intermeshed closely spaced lines about a predetermined area in which it is desired to form a pocket. The forces are applied until stretching thinning, and, permanent deformation of the sheet takes place along the lines to produce a plurality of permanent corrugations to permit lateral deflection of the predetermined area.