Polypropylene plastic welding rods - Made-in-USA, many profiles avaialble Polypropylene is used in many of the bumpers on import cars. The plastic is usually black, and sometimes gray. Polypropylene has a waxy feel to it and it smears and gets "hairy" when sanded at high speed. If you have determined that the plastic you are going to weld is polypropylene, this is the plastic welding rod you need. Use this plastic welding rod with either Polyvance's airless plastic welder, a hot air plastic welder, or a nitrogen plastic welder. Works with airless, hot-air, and nitrogen plastic welders.Made in USA