Secret Messages

Common household items can be used to create secret messages.

What You Need:

  • Fresh squeezed lemon juice (must be fresh)
  • White vinegar
  • Toothpicks or Q-tips
  • Paper
  • Heat source (light bulb or flashlight)

What to Do:

1. Lemon juice or vinegar will act as ink and a toothpick or Q-tip will work as a pencil. If you choose to use a toothpick remember to use the flat end so that you don't rip holes in the paper.

2. Dip the toothpick or Q-tip into the lemon juice or vinegar. Chose only one for the first message. You can use the other one to write a second message on a new piece of paper. After you have dipped the toothpick or Q-tip in the juice or vinegar, write a message on a blank sheet of paper.

3. Keep dipping the toothpick or Q-tip into the juice or vinegar until you have finished writing the whole message.

4. Set the piece of paper aside and wait for it to dry. This might be a good time to try writing another message with the second liquid.

5. Once the paper is completely dry, hold it over a light bulb or flashlight. Remember not to hold it too close or it may burn. Slowly move the paper around over the light so that the whole message is warmed by the heat of the light. The message should slowly reveal itself to you.

6. Once you have seen your secret message, can you make the writing disappear again?

Question: Did lemon juice or vinegar work better as an invisible ink?

Abridged from:
Science is… A source book of fascinating facts, projects and activities. Second edition. Susan V. Bosak with Douglas A. Bosak and Brian A. Puppa. Scholastic Canada Ltd. 1992.
P. 172.

Other Resources

Secret Messages for Kids Only