CBM aluminium containers are made of a Magnesium-Aluminium alloy. The aluminium requires a special process in order to withstand the aggression of corrosive agents. This process, known as anodizing, brings a surface coating that makes the aluminium resistant to attack from water steam. By means of anodizing, it is possible to obtain covers in different colours. In this way, it becomes possible to differentiate the container destination department according to the colour of the lid.