Let's Experiment!

Mystery Messages

Write invisible messages – Amaze your family and friends!
What do I need?

• Lemon juice or vinegar for ink
• Toothpicks or paintbrushes to write with
• Thin white paper
• A lamp with a 100-watt light bulb

What do I do?

1. Dip a toothpick or paintbrush into your invisible ink and write your message on a piece of paper. Make sure to wait until the ink is dry!! You can tell because the paper will look blank.
2. To read the secret message, hold the paper near the glowing light bulb. Remember, a 100-watt light bulb is very hot so be careful when holding the paper near it. Gradually the writing will appear!!

What’s Happening?
Lemon juice and vinegar are mildly acidic, and the acid weakens paper. The acid remains in the paper even after the juice or vinegar dries. When the paper is held near a hot light bulb the acidic parts of the paper burn, and turn brown, faster than the other parts.

Try It Again!
Try using milk instead of lemon juice to write an invisible message.

Once dry, can you use the light bulb to read the message?

Try other liquids.

Which ones reveal a message when heated by a light bulb?

You can also send secret messages using mirrors. Have you ever tried writing upside down and backwards? Try it and then hold your message up to a mirror.

You could even write an upside down and backwards message using invisible ink so that your friend has to decode the message twice.

Back to Tech Frenz

Let's Experiment!
........................

Food File
........................

How Does That Work?
........................

Amazing Facts
........................