I know this probably isn't the section I should have this in but I thought you guys would be more experienced with yew. I have a stave and there are dark gray spots in the sapwood for no apparent reason. There are knots but it isn't next to the knots. Also, how many growth rings can I violate? I am going for 60-65# @ 26" 64" long bow an it will be a flat bow style. How do you see the grain if it is white on white with the violated growth rings confusing it? I can't see it.