Welding operations are completed in two stages. First, tack weld the base of the crack. The heat knits the sides of the crack together and holds both sections of the component in alignment.

Tack welding is performed at the temperature specified for the material (see table). The weld is best completed in one continuous run from end to end, drawing the welding nozzle tip along the base of each 'V' groove.

The nozzle should be held with its toe in contact with the base of the groove and the heel slightly raised. The sole of the nozzle should be inclined at an angle not exceeding 20 degrees to the groove base. As the nozzle is drawn along, hot-air softens the plastic below the heel of the nozzle and the toe draws the softened material together.

Avoid applying pressure to the weld via the tool, as the material at the base of the groove is thin and not strong. While tack welding, minor misalignment of the panel sides or new inserted material can be corrected by holding the sections in position until the weld has knitted and cooled.

After each welding run, brush the nozzle clean with a brass suede brush. Remove any difficult residue by increasing the heat level to maximum to soften it.