Method of making and seam sealing a paper container

The method of making a paper container resistant to liquids consisting of paper material having a non-paper laminate forming an inner facing, said container including one sheet for the sidewall and a second sheet for the bottom, forming said one sheet into said sidewall and overlapping its ends to form a vertical seam, forming a downwardly extending peripheral lip on said bottom sheet and wrapping the bottom portion of said one sheet about said lip to form a bottom peripheral seam, said method including the steps of generating an electric field adjacent said sidewall at and aligned with the vertical seam and also at and aligned with the bottom peripheral seam and on both sides of said lip, causing said electric field to extend through said sheets between their inner and outer faces, providing adjacent said inner face at both said side and bottom peripheral seams powder of a substance capable of adhering to the laminate of the inner facing, charging said powder to have a polarity to be attracted to and deposited on said laminate at each of said seams in the effective area of said electric field, heating said powder sufficiently to cause it to flow and adhere to said laminate to form a moisture-tight seal at each of said seams.