As you can see, I had two kinds of food colouring in my cabinet, red and yellow. While the yellow is great, the red turned out a disaster... ;) The colour never made it past the thin skin under the shell, and when I peeled it the whites of the egg came away with the shell. Didn't even bother to photograph it. Clearly, different kinds of food colouring has diffferent results - Jayne (who wrote the tutorial) wasn't pleased with her yellow eggs, but got a whole bunch of gorgeous eggs in all kinds of other colours! Take a look, they're amazing.
Have fun making your easter eggs. Happy easter everyone!