Invisible Ink

 Warning! Adult supervision: liquids not for drinking

 Please read the procedure before beginning! After reading, please watch the video. Some activities require more time and cleanup than others. You also have the choice of performing these activities in a way that suits your needs.

Not for children under 3 years. Adult supervision required. Follow approved procedures.

 

Materials

  • 2 Measuring Cups
  • 2 Tongue Depressors
  • 1 Teaspoon
  • Turmeric
  • Baking Soda
  • Warm Water (not included)
  • Hand Sanitizer
  • 3 Paintbrushes
  • Pencil
  • Tray
  • 2 Pieces of White Cardstock
  • 2 Pieces of Pastel Cardstock

Procedure

  1. Add 1/2 cup of warm water to one of the measuring cups using the measurements on the side of the cup.
  2. Add 1 tablespoon (3 teaspoons) of baking soda to the warm water using the provided teaspoon. Stir with one of the tongue depressors until it dissolves.
  3. Place a piece of cardstock on the tray, and use the smaller paintbrushes to paint an invisible design using the baking soda solution. The pencil can be used to draw lines to follow.
  4. Set aside the cardstock to dry. Add 2oz of hand sanitizer to the other measuring cup.
  5. Add 1 teaspoon of turmeric to the hand sanitizer, and stir using the other tongue depressor.
  6. Once the invisible design is completely dry, reveal it by painting over it using the large paintbrush and the turmeric mixture!
  7. Supplies are provided to repeat the activity two more times.

 

Science Behind it!

In a chemical reaction, one or more substances change into one or more new substances. Chemical reactions can be indicated by the formation of new materials, burning, changes in properties such as color or smell, etc. Turmeric is a pH indicator, meaning that it chemically reacts with solutions that contain water based on their pH. A solution is a combination of substances that has the same composition throughout the mixture (i.e. everything is evenly distributed and there are no chunks/clumps/etc.) A solution’s pH corresponds to how acidic or basic it is. Acids and bases are different types of chemicals that have different properties. When turmeric reacts with a solution, it changes color based on whether the solution is acidic or basic. Since the baking soda has no color and is dissolved in the water, the Invisible Ink solution is not noticeable on the page. However, when it is painted over with the turmeric solution, it turns a dark reddish brown, since baking soda is a base. Hand sanitizer is used for the turmeric solution instead of water—while hand sanitizer is part water, it is also part alcohol. This is used so the solution dries quickly—alcohol is volatile, which means it evaporates quickly at room temperature.