waterproofing a knitted bag?

[paperruse.livejournal.com]

I haven't posted in here in a while :)

I am currently knitting a bag that may end up being my new bag for school. I am planning on getting a waterproof fabric to line it with and I was wondering if anyone knew of some way to waterproof the actually knitted material. Is there some kind of spray I could use to do that that wouldn't wreck the bag or make it super stiff? I'm using plain old acrylic yarn. Any ideas would be most helpful. Thanks!