You can also use the underside of your palm, beneath your thumb to do the same thing.
Different woods react differently, dj, in my experience it depends on a lot of factors but hardwoods will try to revert to the bend more than softwoods- the trick is to get your shafts in ahead of needing them, sort by dozens, straighten them, rubber band them together in several places, then store them in a relatively cool, dry, place to season and every few months pull them down, open the bundle, restraighten, and put back. In a year or two you will have some permanently straight shafts.
At least thats how I did it when I had an arrow business and it worked great.