You will need:

  • Lemon juice
  • Bowl
  • Paper
  • Cotton tip
  • Heat lamp ​or hair dryer


1. Squeeze some lemon juice into a bowl.

2. Use a cotton tip to paint your lemon juice onto your gretting card.

What message do you want to send?
TIP: The lemon juice needs to dry so don’t use too much!

3. Focus a heat lamp or hair dryer onto the card so it can dry.

SAFETY: Do not use an open flame, this is a fire hazard. 

4. Heat the paper up until the lemon juice turns brown, but stop before the paper burns.

TIP: Be sure to keep moving the paper or the heat source back and forth so you don’t burn the paper as it drys.

What's Going On?

Why did the color of the writing change when you applied heat? 

The lemon juice you used to write your message has two important characteristics, it is acidic and it contains sugar. 

In this experiment the acid from the lemon juice weakens the structure of the paper. When you add heat the parts of the paper that have been affected by the acid will start to burn first allowing your message to be seen. 

The sugar that is also found inside the lemon juice will form caramel when it is heated and this happens a little bit when you heated up your message. 

Do you think this experiment would work if you used only sugar and water? 

Give it a try! 

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