Do you want to know how the tough exterior of some gadgets (like iPods and etc) is made. Well, this video is going to show you that in order to make them stronger, they need to be anodized (or make to corrode). Listen to the explanation. Interesting.
Check out how the dye can literally “eat” into the material and how the properties of the material change due to the anodizing process. Basically, the rust builds an oxide layer on the material and the colors differentiate the different thickness of the oxide.