Subject line says it, pretty much. My chosen method of straightening a stubborn shaft is to roll it on a table until the high part of the warp is on top, then rub it a few times with a bottle, mason jar, or smooth stone. This takes bends out of POC like a dream, and it works pretty well on sitka too. My understanding is that it compresses the top, longer fibers (a lot like what a sinew backing does on a bow), pulling the shaft into alignment.
Since I'm all into tuning at the moment, I'm wondering if this technique affects the spine at all. My guess (and hope) is no, since you still have the same amount of fiber. Anybody with a spine tester ever done a before-and-after? If so I'd be interested.
Thomas
p.s. I'm really going to have to just suck it up and buy or make a spine tester, at some point...