Lemon

Invisible Ink Demonstration

An invisible ink demonstration will add fun to any Cub Scout meeting. If they haven’t seen this before, it will really get their attention. This would fit in with any science themed meeting or a communications themed meeting. You could also fit it in with a magic theme, such as the Abracadabra theme.

It can specifically be used to fulfill Wolf Elective 1 (It’s a Secret) requirement b:

Write to a friend in invisible “ink”

Just make sure you try it out beforehand to make sure your heat source works out OK and is safe.

Invisible Ink Demonstration

Materials

  • Plain white paper
  • Lemon juice (in a bowl or cup)
  • Cotton swabs

Instructions

  1. Dip the cotton swab in the lemon juice and write something on the paper.
  2. Let the paper dry completely.
  3. Gently heat the paper to reveal the hidden message. A hair dryer works well or a 100 watt light bulb work well. Don’t do this part without adult supervision.

Explanation
The acid in the lemon juice remains in the paper after it dries and weakens the paper. When the acidic parts of the paper are gently heated, they turn brown before the untreated paper does.

Lemon juice is commonly used in this demonstration, but any mild acid will work. Try vinegar or milk instead.

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