How to Waterproof Your Shoes ~ use beeswax as shown here, or, easiest of all, use spray silicone, which is the common method for waterproofing army boots. You can get a huge can of it inexpensively at most military surplus stores or a hunting equipment store.
Sealed joints. When installing a window in a tiled shower enclosure, make sure the joint between the jamb and the cementboard is sufficiently sealed with silicone caulk and a waterproofing membrane. The membrane bridging the two materials creates a stable substrate for the tile.