Be a secret agent and write invisible ink messages using a few basic items you can find around the house in this fun science experiment.

You Will Need:

  • Cotton bud
  • Lamp/light bulb
  • Plain white paper
  • Bowl/cup

The Experiment

  1. Squeeze the lemon juice into a bowl or cup and mix in a few drops of water
  2. Dip the cotton bud into the mixture and use it to write a secret message onto the white paper
  3. Allow the paper to dry and the juice to become invisible
  4. Reveal your secret message by holding it close to a light bulb

The Science

Lemon juice contains carbon compounds that are colourless at room temperature. The heat from the light bulb breaks down the compounds and releases the carbon. The carbon oxidises when it comes into contact with the air and turns brown, making your invisible message visible under the hot light bulb.

Want More Epic Experiments?

If you enjoyed this experiment and want more fun, more science, and more epic experiments, enrol now in our science holiday camps and science classes where kids can learn, experiment, explore, and play!