Any difference between wet sanding metal and plastic? I just replaced the rear bumper cover on our Mustang and was wondering if I could use it to practice wet sanding before I pitch it.

 

If it's painted to match the rest of your car sure, treat it like any other painted surface. When you wetsand paint you're only dealing with the top layer (hopefully). So if it's a PTM finish it won't matter if it's metal or plastic.

Practice away.