Although thermoset polyurethane (PUR) bumper covers are rare on late-model vehicles, there may still be instances where one needs repair. This bumper cover from a 1992 Chevrolet Camaro has developed spiderweb cracks. These cracks occur when dirt and grime settle inside cracked paint and gradually damage the plastic.

Since PUR cannot be melted, nitrogen welders are not effective. However, airless plastic welders can be used to create a hot-melt glue-style repair.