How to write a secret letter

Today I have a fun little DIY from one secret agent to another. Perfect for writing secret notes to a friend, your partner in crime or just for fun and experimentation.

1. Materials: paper, lemon juice, small paint-brush or dip pen.
2. Write a secret message on the paper. Use the lemon juice as ink.
3. Let the 'ink' dry.
4. The message reveals when you hold it over a flame. I just used a stove.
5. Your secret message is readable. Have fun!