black marks that dont wash away - exterior
Our camper has many small to medium sized black marks/smudges that simple will not wash away. It is a fiberglass/resin side model. The marks are typically oval smudges that will not wash off with regular RV wash or Simple Green. I have been afraid to go after them with anything harsher.
Any idea what would cause these and how to get rid of them?
2013 Coachmen Freedom Express 320BHDS pulled by a 2005 F250 King Ranch CC
A rainy day camping is better than a sunny day at work.