DIY Science: Secret Valentine Messages

Just in time for Valentine’s Day, we’re making secret messages with invisible ink for you to send to that special someone!

For this experiment you will need:

  • Grape juice concentrate (thawed)
  • Paint brush or sponge
  • Cotton swabs
  • Baking soda
  • Water
  • Cup
  • Paper


To get started with this experiment, mix together  1/4 cup of baking soda and 1/4 cup  of water. Not all the baking soda will dissolve, this is OK. This mixture will be your invisible ink.

Using a cotton swab or brush, write your secret message on a piece of paper with your invisible ink. Dip your cotton swab into the baking soda and water mixture frequently as you write.


Let the message dry completely.

To read the secret message, paint a thin layer of grape juice concentrate across the paper with a paint brush or a sponge. You just need a light amount of juice, don’t soak the paper. Remember – grape juice stains, so make sure you wear an apron or old clothes!


So, What’s the Science?

Grape juice concentrate is an acid, which as some of you might remember from past experiments reacts with baking soda, which is a base. When you paint the grape juice concentrate over the hidden message, it reacts with the baking soda, changing the color of the “invisible” ink! If you can easily see your message before going over it with the juice, the paper may have acid in it. Acid in paper can react with whatever is placed on the paper. This is why some craft and specialty papers are labeled “acid-free.”

As always, it is important to note that an experiment uses a variable (something that changes) to answer a question. To turn this demonstration into an experiment, you have to change something! Check out these questions to get you started:

  • How do different fruit juices affect the outcome of the experiment?
  • Do different types of paper react differently?

Give it a try and let us know how your experiment turned out on our Facebook, Instagram, or Twitter pages using the hashtag #gscscience!


This entry was posted in DIY Science, Science Explained by greensborosciencecenter. Bookmark the permalink.

About greensborosciencecenter

The Greensboro Science Center offers three fascinating attractions in one wild destination! We are the only facility in North Carolina that offers an aquarium, museum, and zoo. Spend the day with us and come nose to beak with playful penguins, get eye to eye with awesome otters, explore the human body, experience Mother Nature’s fury and fun, and encounter exotic animals like gibbons, meerkats, and lemurs!

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