Just a quick tip for you all. I made a sign this week for our neighborhood Halloween bash using foam core, markers and Outdoor Mod Podge. I painted the Outdoor Mod Podge over top of the letters and let it thoroughly dry. It got put to the test today, because it’s been raining like crazy all day here. I just drove past my sign and I am happy to report that my letters are not running or smudged! Yay!