How to Make Invisible Ink

Do you want to write a secret message? Try making invisible ink! The writing for this invisible ink technique is done using cornstarch. An iodine solution is used to reveal the writing.

What You Need

• Cornstarch
• Iodine
• Water
• Toothpick or Cotton Swab
• Hot Plate or Stove
• Paper

Make the Invisible Ink

1. Essentially you want to make a thin cornstarch gravy. You will write using the gravy, allow the writing to dry, then reveal the message using an iodine solution.
2. If you don't have a pre-made iodine solution, you can make some by adding a teaspoon of iodine to about 10 teaspoons of water. Set the iodine aside for later.
3. Mix about 2 Tbsp cornstarch with 4 tsp water in a pan. Heat, while stirring, until smooth. You can boil the mixture to make a gravy; just be careful not to burn it!
4. Remove the cornstarch gravy from the heat. Dip a toothpick, small paintbrush, or cotton swab into it and use it to write your message on paper.
5. Let the paper air-dry.
6. Brush a small sponge, swab, or paintbrush dipped in the iodine solution over the paper to reveal the hidden message. The message should appear purple.