11. Load the wood grain Channel Mask again and this time set the feather to 5. Fill with darker brown.
12. Load the wood grain Channel Maskonce more. This time, don't feather the selection but fill once again with a darker brown. If you are working on a layer, adjust the layer Opacity to make the grain more subtle.
You are now finished painting the basic grain. Use Color Balance or Hue/Saturation to adjust the color of your wood.
13. To roughen the grain, duplicate the layer that contains the art for the darkest grain. Depending on the image resolution, add Noise at a setting of 30-60 pixels and apply Motion Blur at 12-26 pixels. (You can also try Filter > Pixelate > Mezzotint... instead of Noise.) Adjust the Opacity and Layer Mode (try Soft Light).