Write secret messages using baking soda and water and make the big reveal using a bright yellow spice called turmeric!
(safety note: small children should be supervised around rubbing alcohol. It is poisonous.)
1 Tbsp. baking soda
1 tsp. turmeric
For invisible ink, mix 1 Tbsp. baking soda into 1/2 cup water
For revealing paint, mix 1 tsp. turmeric into 1/2 cup rubbing alcohol (isopropanol)
- Use a cotton swab dipped in invisible ink to write a message or draw a picture on a piece of paper.
- Let the ink dry
- Use a second cotton swab dipped in revealing paint to make the message appear, as if by magic.
The Science Behind the Fun:
Baking soda is white, and when it dries, you can’t see it against the white paper because it is camouflaged and blends into the paper. Turmeric is a kind of chemical called an acid-base indicator that changes color depending on whether it’s in a solution with a high pH, called a base, or a solution with a low pH, called an acid. Baking soda is a base, and turns the turmeric bright red where you wrote the message. Paper has a neutral pH (isn’t an acid or a base), and the turmeric on the paper stays yellow.