I have used Massey finish on bows. That is 2ton epoxy thinned with acetone and applied. On one bow I built, a sinew backed hickory with rawhide covering the sinew I wanted to make it as moisture proof as possible because the hickory, sinew and glue and the rawhide will readily absorb moisture. I used hand rubbed linseed oil first, then the Massey finish, then Tru-Oil and finally a spray of satin poly. As the R/H changes, so does that bow. I have seen it, and another sinew backed osage, change 10# to 20# or possibly more because of the lack of or increased amount of moisture in the atmosphere.
You will never eliminate the transfer of moisture but like Hillbilly said you can slow it way down. It doesn't happen over night either. It takes as long to absorb moisture as it does to release it. Keep your bows stored in a hot box or in a house with heat/ac and you will be fine. When you go out in foul weather, wipe your bow with wax and when you get back in wipe it with a dry rag first then wax.