Abstract: A seam reinforcing bead for stretchable materials formed by cutting, extrusion, or casting is applied to a seam in conjunction with heat and/or ultrasonic energy. In a system for application the reinforcing bead is fed by a first pair of rollers past a heat source, thereby producing a non-equilibrium temperature distribution within the reinforcing bead. The reinforcing bead is then applied to a seam in a sheet of material and compressed by a second pair of rollers. The reinforcing bead may contain an excess of solvent/plasticizer to reduce viscosity during heating and to aid in the reduction of residual stresses.