striker question

[TKE921]

I got a striker that came with a call purchase at NWTF.  It is a 2 piece dymondwood.  When it needed touched up on the contact surface I used my standard 220 grit sandpaper.  When i did this i noticed the bottom turned black when i wiped off the dust with my shirt.  I can get fine clucks and some purrs with it, but it seems to want to slide and squeak if I am trying to yelp with it on a crystal surface.  On regular and green slate it is fine.  Subsequent sanding with the 220 has yielded the same black.?

Any ideas as to what this could be?

[TKE921]

i used scotchbrite first.  when the black appeared i thought it may have been some sort of dirt from the scotchbrite...then the sandpaper.  The same black was there.   I usually use scotchbrite in the field and will use sandpaper every few days if I have been running the striker a lot.

[M,Yingling]

dymond wood i would go with 150 grit ether lay paper in  palm hand and twist  or run the grit  across the layers in wood  on tip striker     dymond wood is hard  the 220 my just be polishing it