UV light also makes it reappear (at least, while the light is shining). I have a post about this I have yet to throw up on my blog, but it’s a fun trick. Ice doesn’t work as well as freezing in the freezer though. Aside from sogginess, it takes a good bit of time. UV light it the more attractive option to me because it’s quicker and less soggy. You get less fading if you apply a different heat source other than friction. A lighter works, haven’t tried a hair dryer.
ETA: Got the relevant post up.
Something else to keep in mind is that the pens indent the paper visibly.
