Don't miss the point being made by several people. A backing just might keep a poorly constructed bow from breaking, just as lots of salt pork can make a bad bowl beans edible. Neither will be very satisfying. Wash, soak and rinse them beans before you put 'em on to cook...slowly. The extra time spent in preparation will pay off in the end. Shave, scrape, sand and shape...slowly, before you string it up. You won't need the extra insurance a backing might offer if your tiller is good. (A little salt pork, however is always a good idea with beans.) Good beans, good bows and good luck with your next one! Good gosh, let's eat!