Invisible Ink

ID: A picture taken in low lighting, to show a “treasure map”. On a blank piece of white paper I drew some mountains, rivers, and other types of maplike features (all imaginary) with a pen. Then on top of it, I drew with the invisible ink a dotted line and an X that marks the spot. When blacklight is shined on the paper, the dotted line and X glow! A container of glowing ink is also visible in the background. /ID

A fun idea for the big kids. This one is pretty involved and takes prep time. (You could delegate the steps of figuring out what supplies you will need to an older child who can tackle that challenge!)

These are the instructions that I used originally.

The gist of what you need is…a blacklight/UV light, and a highlighter that you don’t mind destroying. 😉

You squeeze all the ink out of the highlighter into a cup of heated water, then continue diluting it until it no longer appears visibly yellow when painted on paper with a paintbrush, Q-tip, or other implement that you can dip and then write with. But the highlighter will still show up under a UV light!

Like I said — this takes a lot of setup, but is a great deal of fun for the payoff. I bought small UV flashlights on Amazon pretty inexpensively.

What do you think — would your super spy kid enjoy creating their own “invisible ink” and then leaving secret messages?