I can't tell you what works, but I can tell you that Sharpie's do not. They make a nice bright color, and the fine tips allow for precise coloring. Upon rinsing in the sink, the colored area doesn't seem to lighten up, but the water definitely turns color, and there is a little bleeding onto nearby areas. They might be permanent in the sense that you can't get out the color if you want to. I have had a similar experience with Marvy markers -- the kind you don't need to heat set.