Invisible Ink – Hide a Message in Plain View

When I was a child I remember making invisible ink and writing codes on paper that no one else would be able to read. If you want to be a secret agent or spy then this is an essential skill you need to learn to be able to pass on secret messages! Enjoy…

Mystery, magic and secrets are three of our favourite things and mankind continues to explore these in as many ways as it can. Imagine a blank piece of paper with an entire message written on it but only the writer and the recipient know that there is a note actually there. Invisible ink hasn’t only been used to write messages between friends and acquaintances, however.

shutterstock_125660576During World War I and II there were many messages written in invisible ink and sent in an effort for governments to communicate secretly. Some of the notes were discovered before the messages arrived at their destinations, but there are quite a few that actually found their way to the intended recipients.

It may seem like making invisible ink should be a difficult time consuming difficult process, but it is actually quite easy and can be done using only a few ingredients that can be found around the house.

Easy Squeezy Lemon Invisible Ink


½ a Lemon


Cotton bud/Paintbrush

Bowl and Spoon

White Paper

Step 1: Squeeze the ½ lemon into a bowl.

Step 2: Add a few drops of water and mix well using the spoon.

Step 3: Using the cotton bud or paintbrush, write a message on the blank sheet of paper.

Step 4: Allow the juice to dry completely.

You now have a message written in invisible ink, but how will your recipient be able to read it? Heat will reveal what the note contains, so holding the paper over a candle or a light bulb will make the message appear.

If you try to write a letter with lemon juice only, it will still be visible when it has dried hence the reason for diluting it. The reason why it turns brown, and becomes visible, when heated is because lemon juice is an oxidised substance. The process can be repeated using orange juice, vinegar or wine.


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