Secret Messages with Baking Soda

Use chemistry to make secret messages with baking soda. This would be fun for Valentine’s Day or any time you feel like pretending to be a spy.

Secret Messages with Baking Soda

Make Secret Messages with Baking Soda

Yesterday we made secret messages and 3D paintings using art supplies. Super easy. Super fun. Today I bring you another way to make secret messages. This time all you need is a little science. {And you could even turn this into an experiment if you wish.}


  • white paper
  • baking soda
  • water
  • paint brush
  • small spray bottle
  • a fruit juice that will react with baking soda. Try one of these:
    • lemon juice
    • grape juice {we used white grape}
    • blended fruit and vegetable drink {we used V8 Fusion}

How to Make the Secret Messages:

  1. Mix up some baking soda paint by combining 3 teaspoons of baking soda with 2 teaspoons of water. {It doesn’t need to be exact.}
  2. Paint your message onto white paper. Allow to dry.
    Secret Messages with Baking Soda
  3. Once dry, brush off any excess baking soda to make the message mostly invisible {or at least difficult to read}.
    Secret Messages with Baking Soda
  4. Spray your fruit juice onto the paper to reaveal the message.

    Secret Messages with Baking Soda
    For this one, we used lemon juice.

We found that the messages showed up better when we made sure there was baking soda on the paint brush. It sometimes took painting over the message more than once to get the best coverage.

You’ll also get a more clear message if you don’t brush off the baking soda {but then it’s easier to see without adding the acid…}. It also looks kind of messy.

Secret Messages with Baking Soda
For this one, we did not brush off the baking soda. We sprayed it with lemon juice.

The lemon juice gives the message a yellow tint after it dries.

White grape juice reveals the message without really adding noticeable color.

Secret Messages with Baking Soda
sprayed with white grape juice

The V8 V-Fusion we used was the pomegranate blueberry version. It was reddish in color. The juice reveals the message. I think it was my favorite of the liquids we tried.

Secret Messages with Baking Soda
sprayed with V8 V-Fusion

I was also curious to try water. Water actually revealed the messages as well. The reaction wasn’t immediate though. It was not as prominent as the fruit juices but you could see where the baking soda was painted. It seemed to show more as time passed.

Secret Messages with Baking Soda
sprayed with water

It’s interesting to note that we also tried vinegar. {How could we not, with my son’s love for baking soda & vinegar reactions?} The vinegar bubbled {whereas the fruit juices did not}, but it really didn’t show up any more than the water.

I also want to mention that I never could get the lighting correct for these pictures. The secret messages do really look better than this. And it’s just plain fun to watch the message show up.

Aiden painting his own “message” with baking soda. Here’s what it looked like when I sprayed it with the fruit/vegetable juice.

Secret Message Art with Baking Soda

He was happy with this creation. Wouldn’t you be?

Turn the Secret Message Making into an Experiment

Design an experiment surrounding the different fruit juices {or any liquid really}. Which liquid produces the best result? Which reacts the fastest? Which lasts the longest? Which would be best for a spy to carry?

Design an experiment surrounding the baking soda paint. Does the ratio of baking soda to water change how the message reacts with the fruit juice?

More Valentine’s Day Ideas

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