What kinda elm ,Is it slippery elm which is white, or red elm which looks red- brown ? The latter is the bow wood you want. However it is not a good idea to use the wrap,it will cause it to mold or you will get some nasty black rout spots up and down and they go deep. Don.t worry about the moisture, parafin wax the ends and let dry for 24 hours and put cheap white glue on the outside of stave . The worst thing you could do is trap the moisture in it . good luck Denny