There doesn't seem to be any one area that attracts the stain, I just notice
a slight darkening here and there that I don't get it when I use 'normal'
sand paper. The birch I'm using is quite spalted and soft in spots and it
could be that some of the stain is from the spalting? I seem to get less
staining when I apply diluted shelec as a sanding sealer before sanding. The
following is a sample of what I'm dealing with. The tear-out is more evident
in the picture than it is in real time.
http://tinypic.com/view/?pic=igloi8

"robo hippy" wrote in message
ps.com...
Tom.
I am curious where the dark spots are. I have noticed that sometimes
the end grain will finish out a different color than the flat grain. I
have also had black spots show up on wood that is reaction from the
powder left on my gouges from sharpening. If your wood is dry, it won't
show up at first, but does after a while.
robo hippy