I've carved well over a 100 black cork decoys. Like many, black cork was my choice when I first started carving, I used some Stanley Sureform hand rasps- flat, round rat-tail, convex face to shape the bodies after vertical profile cut-out on a band saw. I actually thought I broke Eric's Craftsman bandsaw while Dennis and I were cutting up three blocks, when the on/off switch stopped working. After clean-up of our mess, I took the switch apart, assuming the contacts were shot. Nothing was wrong...except that the switch housing was packed with cork dust!
Steve, the principal issue with these cork blocks is in the quality of the cork sheet. I think, from what I recall, that this sheet came from Chesepeake Decoy Works. As you know, black cork is simply cork bark particles ground and steam autoclaved to release their resin content, which serves as the binder when the blocks are pressed. The particle size within the cork block is key to the quality of black cork; the larger the particle size, the poorer and lighter the cork density. If you zoom on the pics of these decoys you can see the black cork particles are large, which essentially equates to poor particle-to-particle adherence. I can't work these with a burr bit, even a fine one without particles flying-off constantly, often leaving large voids. I use a 1/2" diameter 3" long sanding drum mounted on a mandrel in a Foredom handpiece to essentially sand these into finished body shapes,. as well as to outline the tertials, primaries and shoulder/cape feather groups. This minimizes the filling, but, as you pointed -out enhances the volume of finely charged cork dust. I usually end-up doing three filter changes with the Tornado 1000 when grinding a cork body, because the filter plugs so quickly.
The old refrigerator cork that I have seen blocks of had quite fine particles, but it was poorly bound. The life vest cork often was doweled together-like the balsa blocks in that life raft I made canvasbacks from when the Marquette Maritime Museum folks decided to pitch it.
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This is a threatening mallard decoy I made for a jerk line. Note the second coat of Val-oil's sealing abilities!!!
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These were made from The Duck Blind's 11lb density cork...very nice material to work with, but still messy! There is a 1/2" diameter dowel that runs 8" into the body from the base of the neck, epoxied in place.
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