i have an all sapwood bw bow that took about 2 1/2 inches set. since i have two knots in on limb, i had no intention of making any more alterations to the wood, so i added linen fabric to the back. to my suprise, it seemes to have gained poundage, in addition to being made less likely to break. at 1/2" set, i'd consider fabric backing it. otherwise i'd call it good and leave it!!