Waterproof hide glue?

[WhistlingBadger]

Just came across this recipe, claiming that adding milk to hide glue makes it waterproof.  I am skeptical.  Anybody ever tried anything like this?  Any good results?
https://www.food.com/recipe/waterproof-glue-recipe-93467

I've also read that alum makes it waterproof, but I wonder what that does to the strength and other properties.  I'm about to back a juniper bow with sinew, and of course water solubility is the great weakness of hide glue, so it's an interesting thought.

[Pat B]

I think you would be better off using quality hide glue, sealing the finished bow the best you can and keep it out of wet weather. I took my sinew backed bow "Elkie" on a Colorado elk hunt is 2006. We were camped but a creek bottom at about 9500' where the sun rarely shined. We stored our bows in a 4" PVC pipe with sealed ends and raw rice inside. It rained, it was always humid along the creek but Elkie never lost a bit of cast for the 5 days we were there. To seal Elkie I use 4 or 5 coats of Tru-Oil and satin poly to cut the shine.