The Collaborative International Dictionary of English v.0.48:

Planish \Plan"ish\, v. t. [imp. & p. p. Planished; p. pr. &
   vb. n. Planishing.] [OF. planir, F. planer. See Plane,
   v., and -ish.]
   To make smooth or plane, as a metallic surface; to condense,
   toughen, and polish by light blows with a hammer.
   [1913 Webster]