I need to strip the paint off my lower door mounted ground effects on my 1991 Z28. I was going to use some SEM XXX Urethane Bumper Stripper, but it says not to use it on ABS and several other types of plastics. Do you know what material these are made of or if the SEM is safe to use?

 

Look on the back for the marking. Urethane is probably the most common material used, but that's not to say it's not a PP-something or other. It'll be marked on the back from the production process. Or you can Google for how to test and id the material, which involves things like grinding it to see how it melts or powders, or burning it, or cutting pieces off to see if they float, or you know, you can just look for the marking on the back side.

 

As far I can know, Urethane (PU, PUR) don't needs special adherent to paint plastics.