Abstract: The described embodiments relate generally to aluminum films and pretreatments for improving the adhesion of aluminum films on substrate surfaces. Methods involve providing three-dimensional adhesion surfaces on the substrate that promote adhesion to a subsequently deposited aluminum film. The methods can avoid the use of strike materials, such as nickel and copper, used in conventional adhesion-promoting treatments. According to some embodiments, methods involve providing an aluminum oxide adhesion layer on the substrate prior to depositing aluminum. According to some embodiments, methods involve providing a zincating layer on the substrate prior to depositing aluminum. According some embodiments, methods involve roughening the surface of the substrate prior to depositing aluminum. Some embodiments involve a combination of two or more substrate pretreatments. Described methods can be used to provide more flexibility in subsequent anodizing processes.