Invisible Ink

Write secret messages that appear when heated

A really fun procedure allows kids to perform spying activities. The messages stay invisible until the paper gets heated up.

What you need

• Lemon juice or baking soda mixed with water
• Q-tip or cotton swab
• White paper
• A lamp or iron (for heating)

Instructions

1. Dip the Q-tip in lemon juice or baking soda solution
2. Write your secret message using the wet Q-tip on white paper
3. Let the paper dry completely until the message is invisible
4. To reveal the message, hold the paper near a heat source like a lamp or iron
5. Watch as your secret message appears in brown letters

How it works

When lemon juice or baking soda is heated, it undergoes a chemical change that turns brown, revealing the hidden message.