Kids Science Experiments

Write a Secret Message

Do you want to write a message to your friend, but keep it private (secret)? This is a great way to hide your thoughts on paper.

Our Science Experiment

We are going to write a secret message to our Mom or Dad or another adult in our home.

What you need
half a lemon
half a small cup of water
a cotton swab
a lamp
paper

How to perform this experiment

Squeeze the lemon as hard as you can and let the juice fall into the half cup of water. Use your cotton swab like a pen by dipping it into the lemon water and then writing on the piece of paper.

Watch!

The lemon water writing disappears and dries. Give the note to an adult and have them heat the paper by holding it next to a light bulb (not on the bulb, it could catch fire!). The message reappears on the paper, but this time the "ink" is black!

Why did it do that?

The juice and water mixed together make your message almost invisible. The juice has compounds of carbon in it. When you heat the carbon compounds, they break down and produce carbon. Carbon is black in color.

I wonder what would happen if

I wonder what would happen if I used an orange instead of a lemon?