system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why are some pans not allowed to go in the dishwasher? What happens?
gpt
Dishwashers use alkaline sodas to decompose fat. Pans are often partly or entirely made of an aluminum alloy because it is a good heat conductor and a soft malleable metal for parts like rivets. Aluminum reacts with sodas, especially at elevated temperatures. The surface of hard alloys tarnishes black and any coating may start to peel off even if it is itself unreactive. Physical abrasion may also occur if the pan comes in contact with other metals in the dishwasher and damage fragile coatings.