Just out of curiosity, I know there are some woods that have bad sapwood and you want to work it down to a single growth ring in the heartwood. Osage is an example, but I don't know of any others off the top of my head. Are their other woods that have poor sapwood? If so I imagine there are less of these types of "heartwood only bows" then the "whitewoods" you can use the wood right underneath the bark, so maybe we can get a list of all those woods?