Poly does not last too well on skins, plus it yellows more and more with time. Varathane adheres a bit better and tru oil is great. Another option instead of a hardened finish is to either give it a good coating of Montana Pitch Blend, mink oil, or even butchers wax. It is leather after all, and this seeps into the nooks and crannys very well, but keeps it as a very natural non glare protective finish. Without the waiting time. I have put well over 100 skins on limbs for people, this is what I do for my own bows. I hunted Newfoundland where it poured everyday on me and my bow for a week, the skins held perfectly and did not absorb water.