I know there are plenty of products to remove the black streaks but they always seem to come back. Has anyone found a way to keep them from happening in the first place? I recently bought a new white enclosed trailer and I was thinking about installing drip rail all around it since the one over my walk in door seems to keep the streaks off of the door. Otherwise I was thinking about a huge tarp to throw over the trailer when I'm not using it. That would be kind of a pain to do though...

 

I use liquid wax to remove them and over time a simple wash takes care of the black streaks. The drip rail things help, but doesn't eliminate them. Keeping the trailer covered it the best prevention. Tarp is painful, pole barn is my next investment..

 

Thanks. I'm considering a pole barn type of structure too but I kind of have to back around a corner in order to put my trailer away and I will surely hit it sooner or later.