Missing ingredient in most DIY Mod Podge coasters instructions: "Envirotex" to waterproof them!! This blog explains (wonderfully) exactly how to use it!!! :) Glad I read this before I tried to make mine!
Tile a Shower: Waterproofing membrane Waterproofing membrane is brushed on. It's widely available at tile suppliers. Read more: http://www.familyhandyman.com/tiling/tile-installation/tile-a-shower/view-all