Did you know you could use the juice from a lemon to write a secret message? Materials: Instructions: STEP 1: Squeeze the lemon juice into the plate. STEP 2: Dip the cotton swab into the lemon juice.

William Abel, a mail censor at Iowa's State Prison, Fort Madison, using a hot iron to bring out a secret message written in lemon juice on a letter.Three Lions/Getty Images Humans have had a long ...

Your kids could be sharing invisible messages with each other, but not with lemon juice and a pen, they just need a keyboard.

When I was a kid, my friend had this pen with invisible ink. You could write a note with it and then the person you sent it to had a different pen that made the text show up. We though it was awesome ...

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, available on ...

Breakthroughs, discoveries, and DIY tips sent every weekday. Terms of Service and Privacy Policy. Welcome to PopSci’s at-home science projects series. On weekdays ...

Turning the childhood invisible ink trick on its head, this mod from Make allows you to print out invisible messages with your inkjet printer. Matt Richardson put together this excellent video with ...