Once moving, watch the welding process at the juncture of the welding rod and the material. There must be slight downward pressures on the tip that will cause the rod to be forced into the groove and at the same time there is a widening of the groove and a slight peaking of the material, where the welding rod and groove meet. This peak will be an indicator that all is going at the right pace. This peak will be trimmed off later. This scorching will also aid in determining your speed of welding. If you’re moving too fast the slight peaking will not occur, and if you are too slow the peak of the material at the rod will burn. Be careful not to burn the material, as it is difficult to repair.
Once the welding is complete, turn the hot air setting to zero to allow the heat welder to cool, failure to do this will cause the element to crack and have to be replaced. Cooling It is imperative to allow the material to properly cool down before the skiving process begins; normally a minimum of 20 minutes is required before the trim pass. This allows the molecular structure of both the sheet vinyl and the welding rod to solidify from the effect of the heat. Seams that are skived too soon will show a severe concave effect that cannot be corrected without re-doing the entire process.
Each installer should have their own skiving knife because it must be sharpened to each installer’s likes and habits. The sharpening is done only on the underside of the skiving knife. On the first pass the trim plate will hold the cutting edge of the skiving knife up about 1/32” above the surface of the material; this will also stop the concave effect by allowing the second pass to be more uniform. The first pass should be smooth and without stopping.
Heat welding is a growing in popularity as an installation system. It is an expensive one for tools and equipment. So before attempting to start heat welding, an installer needs to practice I would say it takes about 100 l/f of practice before you can begin to feel confident with the heat welding process. So practice on a scrap piece of material until you become confident in the performance of the tools and equipment as well as your ability to weld.