One light blue (or green) marker and one bright red marker.
To create a "DECODE RED" activity—a popular project where a hidden message is revealed using a red filter—follow the steps below. This activity is designed to take roughly to complete. Materials Needed Paper: White construction paper or cardstock.
If you don't have red cellophane, you can create a "heat-decode" paper using . Write your message with juice and a brush; once it dries (about 15–20 minutes), hold it near a heat source like a lightbulb or iron to turn the writing brown and "decode" it. Write a Secret Message with Matt! DECODE RED - Part 222:26 Min
On a separate piece of white paper, write your secret message using a . Keep the letters clear and thin. Create the "Red Noise" Camouflage (10 Mins)
Use a to scribble, doodle, or write "decoy" words directly over your blue/green message. One light blue (or green) marker and one bright red marker
Place your red decoder lens over the paper. The red filter will make the red marker "disappear" into the background, while the blue or green text will appear dark (nearly black), making the secret message clearly visible. Alternative Method: Invisible Ink
Cut a piece of cardstock into the shape of a magnifying glass or a simple rectangle with a hollow center. Write a Secret Message with Matt
The goal is to cover the blue message enough that it is no longer readable to the naked eye. The red ink should look like a chaotic jumble of lines or shapes.