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Join the American Chemical Society at the Illinois State Fair — Springfield, Illinois |
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A "GOLDEN" SECRET MESSAGE
Write a secret message using Goldenrod Paper.
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Step 1: Take a piece of goldenrod paper 3" x 5" or larger.
Step 2: Write a secret message on the paper using the wax pencil.
Step 3: Hold the paper away from the table and people, and towards the ground, and spray it with a fine stream of Windex. Watch the writing appear!
Step 4: The color will disappear as the paper dries. You can spray the paper at home with Windex to make the writing reappear.
How does it work?
In this experiment you made writing appear and disappear by writing a message on acid-base indicator paper with a wax pencil. Indicators are materials that change colors in the presence of an acid or base. The paper is called goldenrod paper which contains an indicator that is golden yellow and turns red in the presence of a base. The base in this experiment is the Windex™ which contains ammonia. Your secret message remains golden yellow when you spray the Windex with ammonia on the paper, while the rest of the paper will turn red. The wax pencil acts as a barrier on the paper so only areas without wax will turn red. The red color vanishes as the ammonia evaporates in the air and your message will disappear again. You can make the writing reappear over and over again by spraying the goldenrod paper with Windex containing ammonia.
You can make similar acid-base indicator paper at home using turmeric (found in the grocery store) and white paper.
WARNING: Never spray Windex toward anyone’s eyes.
----Contributed by Fran Kravitz, Chicago Section