One of the best all-around cooking materials available, aluminum is moderately priced, sturdy and a good heat conductor. It comes in light- and medium-weight cookware and bakeware; the heavier the gauge, the more evenly it cooks. It's available in plain (matte or polished) or anodized (dark gray) finishes. Plain aluminum finishes can darken and pit when exposed to alkaline or mineral-rich foods, and when soaked excessively in soapy water. Likewise, they can discolor some foods containing eggs, wine or other acidic ingredients. (This discoloration, though not harmful, is unattractive. ) Because aluminum may be reactive and easily scratched, it's often combined with other metals, such as stainless steel. The anodized finishes are chip-, stain- and scratch-resistant but will spot and fade if cleaned in a dishwasher. Extensive research has proven that the old tales of food being poisoned by aluminum are unequivocally false, and those who claim that some foods take on a metallic taste when cooked with aluminum cookware are counterbalanced by just as many who insist they don't.