In this video I show you how to turn simple lemon juice into invisible ink and reveal hidden messages with the heat of a candle. I walk through each step, explain the science of how the carbon ...

Coded messages in invisible ink sound like something only found in espionage books, but in real life, they can have important security purposes. Yet, they can be cracked if their encryption is ...

The CIA has declassified the six oldest documents in its secret vault revealing a host of invisible ink recipes and one way to open sealed envelopes without being caught. The CIA has declassified the ...