Cranberry Invisible Messages

One of my family's favorite parts of a Thanksgiving meal is the cranberry sauce. We bought a few extra cans this year to try out this cool secret message technique. Who knew cranberries could make both our stomachs and our minds happy?

  1. Ages: 3 - 16

  2. <30 minutes

  3. A little messy


Materials you'll need

Step-by-step tutorial

  • Step 1

    To make your invisible ink, mix about 3 teaspoons of baking soda with 1/2 cup room temperature water. Don't worry if the baking soda doesn't dissolve completely.

    Photo reference of how to complete step 1

  • Step 2

    Dip a cotton swab or lollipop stick in the invisible ink and write out a secret message or drawing on your paper.

    Photo reference of how to complete step 2

  • Tip

    You can cut the tips off of the cotton swabs and use the stick to make finer details.

  • Step 3

    Let the messages dry while you make your cranberry spy juice. Use a hair dryer for faster results.

    Photo reference of how to complete step 3

  • Step 4

    Empty a can of cranberry sauce into a pan. Mash up the sauce and spread it into an even layer.

    Photo reference of how to complete step 4

  • Step 5

    To reveal your secret messages, press your paper onto the cranberry sauce with your message facing the cranberry sauce. Gently apply pressure to the paper in the sauce for about 30 seconds. Makes sure you don't submerge your paper into the sauce.

    Photo reference of how to complete step 5

  • Photo reference of how to complete step 7

    Learn moremagnifying icon graphic

    What's going on?
    This experiment uses the chemistry of acids and bases - in this case, the cranberries act as the acid, and the baking soda as the base. Cranberries contain a chemical that changes color depending on how acidic the surroundings are. You painted your secret picture with baking soda - a base. When you pressed the drawing into the cranberry sauce, the baking soda makes those spots on the paper less acidic. This makes the cranberry change color from red to blue, revealing your secret message!

  • Final result!

    Once the paper has dried, coloring your drawing with colored pencils can be a fun way to further personalize your messages.

    Photo reference of how to complete step 6

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