A fastener strip is disclosed having permanently sealed, airtight portion and a reclosable portion capable of maintaining an airtight seal when closed. The permanently sealed portion is generally planar and essentially impervious to air flow. The reclosable portion includes a ridge and a trough, joined at their adjacent ends to a plug, which prevents air from leaking from the adjacent end of the reclosable portion. Additionally, a dam joins the plug to the first backing in an essentially airtight seal, and joins the plug to the second backing in an essentially airtight seal. A method and apparatus for sealing portions of a thermoplastic fastener strip are also disclosed. A method is additionally disclosed for vibrating and molding thermoplastic materials, in which a flow of malleable thermoplastic material is initiated and molded with an effectively dimensioned vibrator that is unitary, with a first matrix for guiding and molding the malleable polymer.