Activity

Invisible ink

Summary
Write a note in (nearly) invisible ink
Science content
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Chemical Changes (2, 7)
Lessons activity is in
Materials
  • saturated baking soda solution in a tub
  • Q-tips
  • card to write note on
  • grape juice in a tub
  • paintbrush
Procedure

Write your note in baking soda solution.
Allow to dry.
The note will be barely visible (though not invisible).

Paint grape juice over the note to make it visible.
(The grape juice turns a different colour when covering the basic baking soda solution).

Notes

Other ideas for invisible ink:
lemon juice invisible until heated
Ex-Lax tablets in water (contain phenopthalein) to write. Add baking soda solution to visualize.

Grades taught
Gr K
Gr 3
Gr 4
Teaching site
After School Programs at Elementary schools in New York City