Well, the disc just sorta floats upside-down in the dye, and the edge of the liquid comes up to the edge of the rim. This is a picture of one of my Buzzz's in the pan- wherever you can see black dye, that's pretty much where it's touching the disc as well. (touching the vinyl, at least)
Don't rock the boat, or the disc WILL end up being submerged, and that just makes for a bad day altogether. I've learned the hard way not to ever move the pan while a disc is being dipped. So has my fiancee, unfortunately.