To make invisible ink, you only need a few ingredients - and a lot of patience! Grab a lemon and watch how it's done. Full-Time Kid is available to stream on pbs.org and the free PBS App ...

I spy invisible ink pens that belong in the kids' stockings — snag a pack for $8 They have built-in UV lights and are suitable for children ages 3 and up, but you'll have fun using them too!

In this challenge, I used a Smiggle Spy Pen to draw a full doodle using invisible ink that only appears under UV light! 🔦🖊️ Drawing without seeing the full lines in real time was tricky—but the ...

Living Ink Technologies is adding a biotech twist to the old invisible-ink trick for a fun algae-based Kickstarter project.

But there are some new uses here too. Apparently Ancient Roman spies, for example, used to use pee as invisible ink—originating the phrase "read between the lines".

Research labs in the US and UK are developing injectable “smart tattoos” that could monitor certain biomarkers in the human body.

Animated lasers, "invisible" messages and other cutesy emoji-filled features are expected on apps like Facebook Messenger and Snapchat, but not from Apple.