The formation of the Double Seam is the result of two separate operations which have a precisely timed relationship. During the first part of the Double Seam formation, the curled edges of the cover components is interlocked with the can body flange. The cover components make up three thicknesses of the Double Seam with two thicknesses of the can body. Second Operation or final formation of the Double Seam will roll and compress these thicknesses into a tight seam. Lining compound previously applied to the curled portion of the cover, forms a gasket or seal within the Double Seam to fill in minor variations or imperfections to assure you of a hermetically sealed can.
Variations in the Double Seam are determined by measurement, visual inspection and testing.