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  • Ms. N Mc Loughlin

Science Experiment 2

Lemon juice secret messages
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Give this a try at home, take a video or photo and send to Sarah our Home School Liaison on WhatsApp 0896053450 to be in the draw for a Tayto Park voucher聽馃槉馃聽聽 Best of luck & Have fun!!!

How to use lemon juice for a 'secret message'

What you need:



Paper or card

Paintbrush or cotton bud

Iron or light bulb/lamp

Note: You can use regular copy paper for this project. However card is a good alternative to avoid a wrinkly paper effect. The more thickly the lemon juice is applied, the darker the result.


1. Cut a lemon in half with a knife. Squeeze the lemon juice in a glass. Add a few drops of water.

2. Dip a paintbrush or cotton bud into the lemon juice. With the paintbrush/cotton bud write a secret message on a piece of paper. Set the paper aside and allow the lemon juice to dry.

3. Heat up the iron, set to high, and switch the steam setting to 鈥榦ff鈥.

4. Slowly pass the iron across the paper and watch the secret message appear.

5. If you don鈥檛 have an iron try holding the paper next to a lightbulb/lamp and watch the message appear as the light bulb heats the paper.

Why does this work:

Lemon juice is an organic substance that oxidizes and turns brown when heated. Diluting the lemon juice in water makes it very hard to notice when you apply it the paper, no one will be aware of its presence until it is heated and the secret message is revealed. Other substances which work in the same way include orange juice, honey, milk, onion juice, vinegar and wine. Invisible ink can also be made using chemical reactions or by viewing certain liquids under ultraviolet (UV) light.

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