Posted 22 October 2012 - 08:03 PM
I am going to jump in here, even though I am not an expert on wood firing. I have fired a few wood kilns around the world.
Black smoke is a sign of incomplete combustion. This is carbon burning off outside of the kiln. You want to time your stokes so that you get "some" smoke, but not black. I have never heard of this indicating damp wood. You could probably hear steam being given off if the wood is damp.
Of course you want to avoid damp wood, as this reduces the efficiency of your firing.
TJR