Walls and Ceilings - shetrock mud

will sheetrock mud adhere to bare wood surfaces?

Wood shrinks and swells too much.
The mud will crack.

I do not only home repair and remodeling, but for close friends and family I make large rocking animals or funiture for thier firstborn. Being on a very tight budget, I have had to use some pretty old nasty wood at times. After a couple of passes with the belt sander I mud it good, finish sand it and make sure to use a decent primer and enamel. Many of these items are over 30 years old and are holding up very well.

20 years ago I had a small kitchen fire that charred one end of the cabinets over the counter. I wire brushed the burned wood real good to get all of the loose stuff out and then shop vaced it good followed by wipeing with a damp rag and immediately began building up layers of mud. once it was up to level I sanded it smooth and painted it with a good enamel. This section sits just above the sink to the side of a window so it is subject to moisture and drying repeatedly and there is no problem.

The key to success in both of these cases is a good sealer coat of a decent enamel to keep moisture from penetrating.

GOOD LUCK!