Aluminum is the ideal material for use in the production of curtainwall and windows. It is non-magnetic, lightweight, durable, and highly resistant to corrosion. When aluminum is exposed to oxygen in the atmosphere, it forms a natural, thin, aluminum oxide layer on the surface of the metal. This layer helps to protect the underlying aluminum from corrosive agents. To improve and control the properties of the aluminum oxide layer, architectural metal finishing companies put the raw material through a coating process known as anodizing.