I only do one coat generally...Some people mention doing two coats, not to "layer" it, but to make sure you didn't miss any spots. I don't think I'm totally sold on even being able to layer AIO, with its cleaning abilities and all. Once the AIO is down, then I start to layer the SG..maybe 2 or 3 layers over the course of a week...by then I don't even want to look at a Klasse bottle for a few months. That's what's great about Klasse though...after 2 or 3 coats, I don't have to! :xyxthumbs