Been meaning to post this. For some it may be a no brainer but I thought I'd pass it along. My son and I share a plastic bucket to wash our cars. I always rinse it out, he doesn't. I've noticed a fair amount of road grit in the bucket that accumulates after a car wash. This stuff can get in your sponge, mitt, whatever and its just like sandpaper on your finish. Always make sure you are dealing with a clean bucket. I rinse ours before and after washing my car.

Pat