Re: Painting Aluminum rail
Sand out the scratches, if they are bad start with 320 then 600 to get rid of the sand marks then hit it with etching primer you can get at any auto parts store then paint.
The primer isn't really primer as in it doesn't really fill imperfections but actually eats into the aluminunm to give the paint a good bond so any scratches in the rail will be in the paint if you don't sand them out.