Invisible ink

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
  • saturated baking soda solution in a tub
  • Q-tips
  • card to write note on
  • grape juice in a tub
  • paintbrush

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).


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