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February Science Challenge

Get involved in our February Science Challenge to use Invisible Ink!

Making invisible ink is a lot of fun, you can pretend you are a secret agent as you keep all your secret codes and messages hidden from others. All you need is some basic household objects and the hidden power of lemon juice. The challenge is to bring in a secret drawing to test in class.

Materials:

  • Half a lemon
  • Water
  • Spoon
  • Bowl
  • Cotton bud
  • White paper
  • Lamp or other light bulb

Instructions:

  1. Squeeze some lemon juice into the bowl and add a few drops of water.
  2. Mix the water and lemon juice with the spoon.
  3. Dip the cotton bud into the mixture and write a message onto the white paper.
  4. Wait for the juice to dry so it becomes completely invisible.
  5. When you are ready to read your secret message or show it to someone else, heat the paper by holding it close to a light bulb. Please remember to ask for an adults help when heating your secret message.

How does it work?

Lemon juice is an organic substance that oxidizes (combines with Oxygen) and turns brown when heated. Other substances which work in the same way include orange juice, honey, milk, onion juice and vinegar.