I'm sure it has to do with unstable molecules. The same material that Reed Richards made the FF's costumes out of. So that they can stretch, turn invisible, and become fire. Also, adhere to just about anything. I wore a domino mask for Halloween one year when I was dressed as the Riddler. I kept having to reapply spirit gum to the inside because it kept sliding off. Could have really used some superscience that night.