itting is primarily an aesthetic problem that, practically speaking, never affects strength.
Attack is, of course, more severe on untreated aluminium. Surface treatment (anodising, painting or other coating methods) counteracts pitting.
Cleaning is necessary to maintain the treated surface’s attractive appearance and its corrosion protection. Rinsing with water is often sufficient. Alkaline detergents should be used with care. Mild alkaline detergents are now available. These are used in, amongst other areas, the industrial cleaning of aluminium.
Pitting can be prevented by cathodic protection (above). It is also important to design profiles so that they dry easily.