Swamp Thing,
On all my sinew wraps and even some of my sinew backing, I use crystalized pitch melted in denatured alcohol...The pitch must be crystalized though...Once I paint it over the sinew, the alcohol evaporates leaving a hard protective covering that has yet to fail me...I have a sinewed bow that I will hunt in the rain with and watch the water bead and roll away, same for arrow wraps...This is a recipe I got from PatB a long time ago...
Don
PS Jake, not trying to get off topic, just trying to answer Swamp's question...I use a pitch, tallow and beeswax mixture melted together until it resembles a paste wax consistency if your trying to stay with all natural ingredients...Same as Rich "half eye"