Check out my Prize Winning Instructable - as seen on Lifehacker – for full details on how to cheaply and easily waterproof your canvas or cotton gear, it also makes a great conditioner for leather.

All you need is equal parts beeswax and canning wax, a double boiler, paintbrush and a heat gun or torch to apply it. I tried my jacket out both before and after waxing it and the difference was amazing.