Make Your Own 'Glow-In-The-Dark' Water.

You can use a fluorescent marker (Yellow, Green and Pink work well) to make a fluorescent
solution that glows under Black Light. Simply cut open a non-toxic highlighter pen and remove the several inches of the fibrous, inner colored core. Soak this core in water for several hours to release the fluorescent coloring inside. You now have a solution that will glow when exposed to Ultraviolet (Black) light.

Use the fluorescent liquid for fun projects such as putting on a stamp pad and marking items as “secret”, create a secret code mark or ”stamp” for use with friends, or as actual readmission ink to your own private club.