What you’ll need:
- Lemon juice
- Cotton bud or a thin paintbrush
- Dry cloth
- 15-20 minutes
Add the lemon juice to the cup.
Soak the cotton bud or paint brush in lemon juice and write your message on the paper. Wait for it to dry, be patient as if it is not dry it will run.
Once it is dry your message will be invisible!
Very carefully with the help of an adult of needed, put your piece of paper on an ironing board and the cloth over the top. Use an iron on a dry (not steam) setting to reveal the message!
You could try milk or fruit juice and compare the results – which would be the best to pass on a coded message?