This is a fun experiment for kids!
- Paintbrush or Q-tip
- Heat source
1) Juice half a lemon. Add a little bit of water.
2) Paint words or pictures on the paper. Allow to dry thoroughly.
3) Hold the paper over a stove top burner (turned on medium or high) or other heat source to see the message appear!
Please be careful. I would recommend an adult completing step 3 and not allowing your child to do this. You may even consider using it as an opportunity to discuss stove safety.
You might also try this experiment with vinegar, juice, or milk to find out which makes the best invisible ink!
How does it work?
“The acid in the lemon juice breaks down the cellulose of the paper into sugars. The heat supplied tends to caramelize the sugars, making them brown and revealing the secret writing.” Source: TLC – How Stuff Works.