Attachment for sealing seams

A method for forming a waterproof seam between at least two fabric members, comprising the steps of:

• providing a quantity of thread comprising between about 2% and about 6% by weight of a thermoplastic polymer selected from the group consisting of polyurethane, nylon, polyester, polyolefin, and vinyl;
• employing a sewing machine to incrementally draw said at least two fabric members from an upstream side of said sewing machine towards a downstream side of said sewing machine, and to cause a needle to puncture said at least two fabric members at regular intervals and to draw said thread through said punctures, to form a sewn seam;
• inserting a strip of thermoplastic polymer selected from the group consisting of polyurethane, nylon, polyester, polyolefin, and vinyl between said at least two fabric members while forming said sewn seam;
• providing a plurality of heated, driven rollers;
• providing a pair of idler rollers opposed to each of said driven rollers;
• providing a continuous belt disposed over said idler rollers;
• passing said at least two fabric members with said strip of polymer therebetween between said heated driven rollers and said pairs of idler rollers;
• urging said heated driven rollers towards said pairs of idler rollers while said at least two fabric members are incrementally drawn from said upstream side of said sewing machine towards said downstream side of said sewing machine, so as to apply heat and pressure to said seam so as to melt said polymer from said thread, whereby said polymer from said thread fills said punctures, and so as to melt said polymer from said strip,
• allowing said polymer comprised by said thread to cool and solidify, whereby said punctures are sealed against ingress of water;
• and
• allowing said polymer of the strip to cool and solidify, whereby said seam between each puncture hole is sealed against ingress of water;
• and
• wherein at least two heated driven rollers are provided, their axes being generally coplanar, and wherein at least one downstream heated roller is driven at a greater speed than an upstream heated roller, whereby tension is exerted on the at least two fabric members.