You can try black light if you wish. I wrote in the three colors of grease pencil I had and looked at it with black light. The black light didn't help on the black or blue pencil, but the orange did fluoresce a bit making it a bit easier to read.
Infrared cameras are expensive, but black lights can be found cheap ($10-$15). Also, black lights have a wide variety of uses, including with collectibles and memorabilia. If it doesn't help with the vault writing, you'll find other good uses for your black light.
Last edited by drc; 06-07-2009 at 04:02 PM.
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