Aluminium profiles are used extensively in applications such as window and door frames, display counters and partitions. Such aluminium profiles come in several finishes, among which are metallic finishes such as the well-known silver-metallic and gold or bronze metallic finishes. Recently a brown-metallic finish has become popular as well. These finishes involve anodizing the aluminium. Alternatively, aluminum profiles have been coated with paints which are baked onto the aluminum. To anodize aluminum, it has to undergo an electro-chemical process which is rather complex, expensive and limits the colours obtainable. Aluminum profiles that are painted require first to undergo a preliminary process of undercoating in order to provide a suitable surface for the paint to adhere to, since paints do not adhere well to aluminum.
Although many advances and developments have taken place in the coating industry, including the art of finishing aluminum profiles, there are a number of problems that have as yet not been overcome. First of all the finished aluminum profiles, which are used for so many diverse applications, require special resistance against degradation by light, chemicals, corrosive atmospheric gases and other pollutants, because they are used so much under outdoor conditions in displays and window frames where ultra-violet light, industrial gases and other weather conditions deteriorate the coating and the aluminum. This is particularly true for use of aluminum near coastal areas, where oxygen and salt water in the air subjects the profiles to severe corrosion.
A further problem is caused by the fact that modern household and sanitary cleaning materials contain bleaches and alkali which react with aluminum and deteriorate its surface. These problems dictate that the aluminum profiles for use in such applications must have complete protection from contact between any corrosive atmosphere and the aluminum. This protection is very difficult to achieve in profiles with intricate channels and grooves, as is the case with aluminum profiles. Yet the demand for aluminum profiles for such applications is ever-increasing, particularly for profiles with metallic finishes at a reasonable price.