a plastic bag having a reclosable plastic zipper is provided with a tamper - evident , non - reclosable peel seal formed by applying an adhesive to a treated strip adjacent to the interlocking zipper . the treatment is preferably by corona discharge , which causes the adhesive used to provide the peel seal to preferentially adhere to the treated strip when the peel seal is broken . a method for manufacturing the reclosable plastic zipper includes the steps of extruding a zipper profile , treating a portion of its surface , preferably by corona discharge , applying an adhesive to the treated portion , slitting the profile lengthwise , and folding over one of the resulting sides of the zipper to interlock them with one another .