Mantle

v. i.
  1. To unfold and spread out the wings, like a mantle; -- said of hawks. Also used figuratively.
  2. To spread out; -- said of wings.
  3. To spread over the surface as a covering; to overspread; as, the scum mantled on the pool.
  4. To gather, assume, or take on, a covering, as froth, scum, etc.