How to write secret messages with invisible ink and read them with UV light

Are you a London-based top secret agent working for MI6 who’s been tasked with crafting a secret correspondence?

You’d like to know how to write secret messages with invisible ink?

Then you’ve landed on the right not-so-secret page! We will tell you all the secrets of the trade. Ready?

What is invisible ink?

Well, it’s pretty self-explanatory. Invisible ink, also called  sympathetic ink, is a kind of ink you can’t read without a decryption device. The method we’re going to describe is a cheap trick still used by aspiring spies all around the world. You won’t have to steal the enigma machine or hire a crew of genius mathematicians. All you’ll need is less than $20. Ain’t too much to become a spying scribe!

How to write secret messages

The first thing you should do is buy the right spy pen on Amazon, a pen powered by invisible ink which your readers will only be able to decrypt with a UV flashlight.

If you’re planning to go on a lot of covert missions all around the world, you’ll need a good supply of invisible ink spy pens and top secret notepads. This is the perfect kit for you.

ink spy pens and notepags secret messages

Working as a spy writing secret messages won’t break the bank: this kit of 12 notepads and 10 pens costs less than $15 at time of writing.

We’ve found another set of 30 spy pens, that’s enough to write with a different pen each and every day of a 1-month spying mission. Moreover, these spy pens look like kids birthday party favors.

30 spy pens

How to read secret messages written with invisible ink?

If you want to read secret messages written with magic ink, you’ll need a small UV flashlight (which can also serve other investigative purposes). Here’s a pack of 2 ultraviolet light detectors, just in case you lose one running away from nasty villains. They’re pretty cheap too, $5 a pop!

UV flash light secret messages

You can even buy a device which integrates both an invisible ink spy pen AND a mini UV flashlight, the ultimate spying tool.

invisibe ink spy pen and uv flashlight

The DIY method to write secret messages

If you want to play it old school, there’s a homemade DIY method to write secret messages: simply use a cotton swab and some lemon juice or vinegar to pen your message.

Then heat the sheet of paper with a hair dryer or by holding it near to a flame for 5 to 10 minutes. You’ll see the message gradually appear on the page, like magic!

lemon ink secret message

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