19190 Blue Ghost

The invisible ink dries completely clear on the page, and it's honestly a bit spooky when the glowing blue letters suddenly appear under a UV light. I used it for a scavenger hunt and the 3 oz bottle went further than I expected, even with lots of test notes.

Wrote a secret message to my partner on a birthday card, and watching it glow blue under the UV light was honestly magical. The ink dries completely invisible, so you'd never know it's there without the flashlight.

The 3 oz bottle lasts way longer than I expected, which is nice since you only need a tiny bit for hidden messages. Watching notes and doodles light up a bright blue under a blacklight never gets old, and the fact that it's bulletproof means my secrets stay put even if the paper gets wet.