Share top secret messages!

Wouldn’t it be great to pass on secret messages that only you and your friends could read? This is an experiment that you can carry out using materials that we can find in any kitchen.

There are many ways to create invisible ink. But for this experiment we will use the following materials:

✔ Lemon
✔ Paper
✔ Clean brush or cotton swab
✔ Desk lamp

Process

This experiment is very simple and fun at the same time! Be sure to invite your friends so everyone can try to make invisible ink and exchange invisible messages at the same time!

The first step is to get a lemon and squeeze its juice into a small container. Then dip your clean brush or cotton swab into the container, as you will be using the lemon juice as ink. Write on a blank sheet of paper with the “inked” brush or cotton swab and let it dry. To read the hidden message, you will have to apply heat to the paper. Turn on the lamp and hold the paper close to the bulb, so the bulb can heat the paper. The heat from the light bulb will cause what you wrote to go dark, allowing you to read the invisible messages!

Discussion

There are other materials you can use if you don’t have a lemon. You can use milk, baking soda mixed with water, vinegar, or grape juice. Basically, you can use anything acidic as invisible ink. As for the heating agent, you can make use of other sources of heat, such as sunlight or a candle. However, you will need to have parental supervision if you are going to use a candle as a heat source for this experiment.

Milk, lemon, vinegar, grape juice, or any other acidic liquid weakens paper when exposed to heat. When you apply heat to it, the part where you wrote your message oxidizes and burns faster than the dry paper around the ink. This part will turn brown, thus revealing your secret message.

There is another way to decode the secret message and make it appear without having to apply heat. You can achieve this by putting salt in the ink after writing on the paper. Wait about 60 seconds before wiping the salt off the paper, then apply color over the writing with a crayon. You will see how the message appears!

You can also reveal the message by applying grape juice on the message. You should be aware that the writings will change color when you apply the grape juice!