Secret Message Paint

2 tablespoons water
1 tablespoon baking soda
4-5 drops of food coloring
A paintbrush and paper

1.  Mix 1 tablespoon of the water with the baking soda in a small plastic container.

2.  Mix, in a separate small plastic container, the other 1 tablespoon of water with the food coloring.

To create the secret message:
Dip a paintbrush into the baking soda/water mixture and write your message on a piece of paper.  Let dry completely.

To read your secret message:
Dip a paintbrush into your colored water and paint over the secret message to reveal it.