You will need:
Lemons, Stick or small paint brush, Paper, Heat source
What To Do:
- Squeeze the lemons and place the juice in a small container.
- Use the juice as ink by dipping the paint brush or stick and writing on the paper
- Leave the paper to dry.
- When you are ready to read the invisible message, hold the paper to sunlight or a lightbulb to heat gently.
- The heat should cause the writing to darken to a pale brown so it can now be read.
HOW IT WORKS:
Lemon juice is acidic and weakens paper when applied to it. When the paper is then heated, the remaining acid turns the writing brown, revealing the message before discolouring the rest of the paper.