Card Inside Eggshell

For all of you who know the card to ashes to arm technique, this is a nice alternative.
Get some ALUM (Amonia Aluminum Sulphate) and mix it with a pint of vinegar. You paint a 5 of Hearts (or anything else) on an eggshell and leave it to dry for an hour. After, you boil the egg so it hardens and let it go cold (don't put it in the fridge). After you crack the egg, the 5 of Hearts can be seen now on the inside of the eggshell.
I'm sure you can all use your imagination and integrate this into a charming effect.

Apperantly you can buy ALUM from the drugstore, but I found it at the grocery store in the spice section. Check your local Safeway, Save-On, Wall-Mart, etc...