Aluminium naturally forms an oxide coating that keeps it rust-free under normal conditions. This make is very durable. It only corrodes when exposed to salty or acidic conditions, and even then it is superior to most metals.
Brushed aluminium looks very professional for signs. Company embalms or tittles look impressive as aluminium silhouettes, especially when on a dark background. Such aluminium signs make a bold, professional statement. They often featured on the outdoor structures of building, where they lasted for years.
A generation ago aluminium was considered very difficult to paint. The only real options were flat matt paint that looked unimpressive and was prone to damage. The technology for this was developed for World War 2 planes and latter applied to some vehicles and other aluminium products. It was never too popular, and not used in advertising.
Aluminium could also be coloured by with anodising. Aluminium was treated with electricity, basically as one of the terminals in a battery. This coloured the metal’s outer porous oxide layer. This anodized aluminium had a rather bright, colourful retro-future look, and proved popular for cups and small utensils. But this anodized metal was never appropriate for vehicles large structures or any advertising mediums.
Modern aluminium signs can now feature baked on enamel paint. This is glossy and appealing, meaning aluminium signs are both durable and able to complete with the appeal of any other signs.
We often see aluminium signs in advertising: