If you use a beamsetter you will find cleaning the film on the outer lens will degrade the pattern.Here in New Zealand we test headlamps with a beamsetter every six months as part of the safety inspection - as well as being out of adjustment,we also fail bad patterns.
The lens cleaning kit we use has a clear lacquer that is applied after the sanding to restore lens thickness,and so retaining a good pattern.
The lens cleaning kit we use has a clear lacquer that is applied after the sanding to restore lens thickness,and so retaining a good pattern.