I backed a red oak board bow, made from a scrap off cut that was too ugly to get too serious about. I used heavy brown paper shopping bag stock. the slivers didn't even slow down going through it. I ended up glueing them, and wrapping with dental floss, and covering with more brown paper. That worked OK. I really want to try some Tyvek some time. 'Course there's about a thousand things I want to try before I cash in.
piper