Aluminum is the third most common element on the planet after oxygen and silicon. Alloying it with other metals such as copper, magnesium, manganese, silicon, tin, and zinc, increase its durability, and hardness as well as decreasing its vulnerability. Its malleability and conductivity and affordability make it the most common kitchenware material. However, aluminum is a very reactive metal, a thin layer of oxidation forms on any exposed aluminum surface. This layer protects the metal from further oxidation. Anodising increases this layer enhancing its durability, but also decreases its heat efficiency.
Just being exposed to moisture in the air will cause the nice mirror surface of brand new kitchenware to become dull, everyday use, washing with or without a dishwasher will dull it further. NONE of which affects it’s function. For some reason people equate a shiny surface with a clean surface and as your car runs better after a car wash, freshly polished items must work better.
I picked up a jar of Blue Magic Aluminum Polish and it works a treat to get a shine on dishwasher dull surface. For a smooth pot it is just as easy to zip around the surface with a dishrag, smearing it on and then going around again to polish it off. But for fun I went after this garlic press with a wool buffing head on my drill, it didn’t buff any better, just a little faster if you don’t count the time I spent pulling out the drill.
Aluminum is also usually very soft (except when hardened with anodizing or magnesium) so before I go to polishing, I tackle scratched surfaces with VERY fine steel wool and Barkeppers Friend, to reduce the scratches or at least get them all going in the same direction.