In order to keep your aluminium doors looking great and retaining their weather resistant properties, it is necessary to clean the surface regularly with water and a mild detergent. It is important, however, that you make sure your maintenance measures don't cause more harm than good, as many harsh cleaning solutions can actually cause damage to your aluminium doors.
Although you will need a sponge to wash down your aluminium doors, it is important that you don't use anything too abrasive, to avoid damaging the metal or removing any finishes. This is especially true if you are cleaning an alloy metal, as the aluminium may be blended with a much softer metal that is susceptible to scratches and marks.
Metals such as these can become dull and worn looking after several years of exposure to the sun, causing the metal to oxidise, creating a dully milky-grey layer to accumulate on the surface of the aluminium. While this layer can be stripped away, using harsh household cleaners may just cause further damage to the frames.
To remove this dull and grimy layer, without using any harsh chemicals or abrasive materials, you can make a completely natural paste by mixing together half a cup of lemon juice and half a cup of baking soda, and applying it to the door frames. You can let this mixture sit on the surface for several minutes, and after wiping it off with a damp sponge, your doors should be polished and shining as good as new.