Invisible Ink

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In this hands-on activity (on page 2 of the PDF), learners experiment with lemon juice and paper to create a message that can only be revealed using chemistry. Using an oven as a heat source (requires adult supervision and assistance), learners discover that different things combust at different temperatures since the lemon juice browns and the paper does not. This in one of three activities in the Take Home guide for the Chemistry of Toys unit in OMSI's Chemistry Lab. Also included in the PDF are: Chalk It Up and Flubber.

Quick Guide

Preparation Time:
5 to 10 minutes

Learning Time:
10 to 30 minutes

Estimated Materials Cost:
1 cent - $1 per student

Age Range:
Ages 6 - 14

Resource Types:
Activity, Experiment/Lab Activity


Materials List (per student)

  • lemon juice
  • one piece of paper
  • one small brush or cotton swab
  • oven


  • Physical Sciences
    • Heat and Thermodynamics
      • Heat and Temperature
    • Chemistry
      • Acids and Bases
      • Oxidation-Reduction Reactions

Informal Categories

  • Crime Science
  • Food and Cooking


To use this activity, learners need to:

  • see
  • see color
  • read
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


This resource is part of:

Access Rights:

  • Free access



Funding Source:

  • National Science Foundation