system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why do jeans shrink after washing and then go back to normal after being worn?
gpt
Denim is a very strong material, it's actually so strong that it's used in paper money. When it gets washed and then heated up when dried, the fibers in the strands tighten up due to the heat. Wearing them forces the fibers back apart. It's actually what causes jeans to eventually tear because the fibers have contracted so many times that they lose their strength.