Secret Message Science
Create secret messages for your friends with this sneaky Science Experiment for all ages to enjoy. In this experiment you will create a watermark which will only be visible when the paper that you are using is wet. You will use two sheets of paper, one wet and one dry, and a ball point pen. Have fun sending secret messages to friends and family members.
The pressure that you exert onto the ball point pen onto the dry paper changes the paper fibers of the wet sheet underneath. This change is only visible when that paper is wet and disappears when the paper is dry.
How to Do It