How to Make Invisible Ink With Baking Soda

Easy instructions for making non-toxic invisible ink using nothing more than water and baking soda.

Steps   [edit]

  1. Mix equal parts water and baking soda.
  2. Dab a cotton swab, toothpick, or paintbrush into the mix.
  3. Write a message onto white paper, using the baking soda solution as 'ink'.
  4. Allow the ink to dry.
  5. Read the message. There are two possible ways to read it:

    • 1. Hold the paper up to a heat source, such as a light bulb. The baking soda will cause the writing in the paper to turn brown.
    • 2. Paint over the paper with purple grape juice. The message will appear in a different color.


Tips   [edit]

  • Baking soda and grape juice react with each other in an acid-based reaction, producing a color change in the paper.
  • The baking soda mixture can also be used more diluted, with one part baking soda to two parts water.
  • Grape juice concentrate results in a more visible color change than regular grape juice.


Warnings   [edit]

  • If you are using the heating method, avoid igniting the paper - don't use a halogen bulb.


Things You'll Need   [edit]

  • Baking soda
  • Paper
  • Water
  • Light bulb (heat source)
  • Paintbrush or swab
  • Measuring cup
  • Purple grape juice (optional)