Most folks think the sapwood is worthless. They are missing out on a lot of good bow wood. I have made hunting weight bows with only osage sapwood. One was a 3" diameter pole and only had a pencil thick heartwood. Not as snappy as an all heartwood bow but a good bow none the less. The sapwood is more susceptable to rot so care should be taken from the time the sapling is cut. For drying the wood I seal the ends with shellac then give the pole a few weeks to stabilize. Next I bandsaw the pole in half lengthwise. To prevent twisting and too much backset I bind the two halves back together with spacers between them. This allows for good air curculation and helps prevent twisting and uneven backset. I would rather add controlled reflex later than depend on the wood to draw up in even, untwisted reflex.