The Collaborative International Dictionary of English v.0.48:

Grainer \Grain"er\ (gr[=a]n"[~e]r), n.
   1. An infusion of pigeon's dung used by tanners to neutralize
      the effects of lime and give flexibility to skins; --
      called also grains and bate.
      [1913 Webster]

   2. A knife for taking the hair off skins.
      [1913 Webster]

   3. One who paints in imitation of the grain of wood, marble,
      etc.; also, the brush or tool used in graining.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Grains \Grains\ (gr[=a]nz), n. pl.
   1. See 5th Grain, n., 2
      (b) .
          [1913 Webster]

   2. Pigeon's dung used in tanning. See Grainer. n., 1.
      [1913 Webster]