What makes paint stick? (Encore)

Paint goes on wet, then it dries -- and it's stuck there. But how does it stick? We're going to zoom way in to find out. We'll visit a forensic chemist, a painter who makes his own paint and a party happening at the molecular level. Plus a brand new Moment of Um answers the question: "How does sand get on the beach?" And we'll add a brand new group of listeners to the Brains Honor Roll. This episode of Brains On is sponsored by Mr. Clean Magic Eraser (mrclean.com/brainson) and Marc's Mission (wayofthewarriorkid.com)