Hey Gang,
I've been using Hare line water shed for water proofing feathers for a few years now. It's a fishing fly water proofinging treatment. It works pretty well..not perfect..but it deals with light to moderate rain pretty well.
I've recommended it before when the topic comes up on this site.
Anyway, I recently bought a "new" bottle from a vendor. Not a sponsor here as I can't find one that sells it.
The fluid in this bottle didn't penetrate the feather at all...just beaded up on the surface.
I contacted the manufacturer to find out if they changed the formula, bad batch etc...
Turns out I had an old bottle of the stuff in the CLEAR bottle.
They found out a few years ago that UV was changing the fluid when they used the clear bottle so they switched to a solid white bottle.
They were nice enough to send me a free bottle of it to replace the bad bottle..really good folks.
Anyway, the point is if you're wanting to try the stuff look for the solid white bottles and steer away from the clear bottles.
Good luck hunting!