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.

During World War 1 and 11 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.

Invisible Ink Pen



3 Tablespoons Hot Water

1 Plastic Cup

Cotton Swab


Step 1: Using the pliers, carefully pull apart the highlighter making sure that all the pieces remain intact.

Step 2: Extract the ink from the cartridge and the tip by placing them in the plastic cup and pouring the warm water directly on them. Allow both to soak for 5-10mins then squeeze the ink out of the cartridge. Repeat this step as many times as necessary until the cartridge is a light colour and the water is dark. You have now made your invisible ink.

Step 3: Squeeze the excess ink out of the cartridge, and leaving it damp, reassemble the pen. If you can see the colour when you write with it on your skin, you need to squeeze more ink from the cartridge.

Store the ink in a spill proof bottle using it to refill the pen whenever it stops writing. This ink can only be seen on the skin using a black light, so is perfect for messages that will be revealed using one.