Tweed case waterproofing?

[Uke Don]

If it were me, I think I would try the spray-on waterproofing used for suede shoes. It does a fairly good job.

[spookelele]

I haven't used it on tweed, but nikwax makes spray on waterproofing. More.. water repelling which is what it sounds like you want. If you drop it in a lake.. it's not going to help you, but it beads water off pretty good, and keeps it from getting into the fabric. I've used it on tents alot, and it works well.