Science Corner: Sending a Secret Message

With Valentine’s Day just around the corner, I thought it was a perfect time to share with you an experiment that you can use to send secret messages to your loved one ;).  This experiment is probably familiar to most of you, but the science behind it is probably not.

Sending a Secret Messages

This is one of my daughter’s favorite things to do.  There’s nothing like getting a blank piece of paper and making a secret message appear!

You will need a blank piece of paper, lemon juice, a q-tip and a heat source (Adults only: A burner in your kitchen or a candle will work well for this).

Steps to Complete:

1. Dip your q-tip in the lemon juice and use it to write a message on the paper.
2. Let the paper dry.
3. Then hand the paper to an adult to reveal the message.
4. Adult: Hold the paper over the heat source until the message appears.  Remove quickly or the paper will burn.  CAUTION: Be sure to take the necessary precautions, such as a hot mat, to make sure that you don’t get burned.

Results

You will be able to read the messages because it will appear brown after being heat treated.

Explanation

The acid in the lemon juice breaks down the paper a bit, thus weakening it.  The weakened paper burns before the rest of the paper, which is why you must remove it from the heat source just after the message appears or the entire paper will burn.

Take It Further

You can try the experiment again using water, which is neutral.  It should not degrade the paper the way the lemon juice does, so the message won’t appear.  You can also try writing messages with vinegar, orange juice or white wine, which will degrade the paper the same way the lemon juice did.

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Coming up in two weeks: 5 Reasons to Make Time for Science Education