Margherita Schiliro (@mmargheritaschiliro) said she was recently alerted that Dawn, an American brand of dishwashing liquid, has a secret second use: It can also be used to wash your hair.

Much like a bar of soap! Lather directly into your hair, or transfer the suds from your hands to your scalp. Obviously, you’ll want to do this while your hair is wet. Otherwise, the solid ...