Back in the day, people used pure aluminum cookware. Why? It is: Abdundant, conducts heat pretty evenly, and is soft to mold into a variety of shapes and sizes.
Now, aluminum goes through a process called "anodizing." What is it exactly? Think: electro-chemical process to make aluminum STRONGER and conduct heat better. It turns into a dark gray, porus material versus the light, super shinny apperance.
It is rare that you will see pure aluminum cookware, for sale, in the domestic field today. It is either: hard anodized with a protective non-stick coating over it or combined with stainless steel.
Here are my top 3 reasons why it is great time to toss out your used aluminum cookware and upgrade your set:
1) Pure aluminum over time, it "worps." The pans "titer-toter" and become uneven on the bottom over time. It will not "sit flat" on your cooking range.
2) Aluminum reacts with acidic and citrus foods, causing a discolor in the pans. Watch out for food like tomato sauce and lemond curd to stain aluminum cookware.
3) Aluminum cookware is just...unattractive. Cookware is getting "cosmetic" and there are a variety of colored and bronze-toned cookware on the market. Not only should cooking and baking be fun, your pans should be, too!