Making Invisible Ink - The Magic of Oxidation

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Updated on May 05, 2014

Grade Level: 8th; Type: Physical Science

What is the project about?

The oxidation project is a fun 'magic' experiment for students to learn about the concept of oxidation by using lemon juice.

What are the goals?

The goal of the oxidation project is for students to learn about the process of oxidation. The students should also be required to explain the science behind the 'magic' of the project.

  • What is oxidation?
  • What is the result when iron and copper undergo oxidation?
  • What is the result when fruits and vegetables undergo oxidation?
  • How can oxidation be prevented?

  • Lemon (1/2 lemon per student)
  • Bowl (1 per student)
  • Spoon (1 per student)
  • Water
  • Paint brush (1 per student)
  • White paper (1 piece per student)
  • Light bulb (a small lamp works best)

Where can the materials be found?

Most materials can be found at a grocery store or all-purpose store (such as Target)

  1. Squeeze juice from the lemon into the bowl.
  2. Add a few drops of water to the lemon juice.
  3. Mix the water and lemon juice with the spoon.
  4. Dip the bristles of the paint brush into the lemon juice/water mixture.
  5. Write a message or draw an image onto the white paper.
  6. Allow the paper to dry completely. The message or image should be completley invisible on the paper.
  7. Hold the paper very close to the light bulb (lamb) - the paper should heat up from the light bulb. *Adult supervision required*
  8. Record observations and explain 'magic' of what you see.

Terms/Concepts: The concept of oxidation and its effects on various materials is essential. The definition of electrons and oxygen molecules should be reviewed as well.


Brooke Greco graduated from UC Berkeley, and has volunteered her time with several after-school learning programs over the last several years. Brooke served as a Citizen's Schools Teacher in Redwood City, CA, where she taught a course on the rain forest. In addition, Brooke served as a teacher at the New Era Galapagos Foundation and taught English and conservation practices to local youth of the Galapagos Islands.

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