amnot a super turkley killer - have shot my share but don't consider myself an expert!

Waterproof calls I use
Quaker boy Hurricane for the box and a Pittman Glass that actually works or runs better by spittin on it!

As far as making a current call waterproof - use a Ziploc bag.....I know of no treatment other than that maybe others do.

Oh tip for ya - on a damp slate - take a bic lighter and flame the surface to dry it out.

JW