How to Make Invisible Ink with Your Kids

Learn three safe, easy methods to make invisible ink at home using common household items.

  1. Method 1: Lemon Juice Invisible Ink. Squeeze fresh lemon juice into a small bowl. If you don't have fresh lemons, bottled lemon juice works too. Dip a cotton swab, small paintbrush, or toothpick into the lemon juice and write your secret message on white paper. Press gently so you don't tear the paper. Let the paper dry completely until you can't see any writing. To reveal the message, hold the paper near a warm light bulb, ask an adult to iron it on low heat, or place it in a low oven (200°F) for a few minutes with adult supervision. The writing will turn brown and become visible.
  2. Method 2: Baking Soda Invisible Ink. Mix equal parts baking soda and water in a small bowl until the baking soda dissolves. Use a cotton swab or small brush to write your message with this solution. Let the paper dry completely. To reveal the message, paint over the paper with grape juice using a clean brush or cotton swab. The writing will appear in a different color than the grape juice. You can also try using cranberry juice or any dark-colored juice instead of grape juice.
  3. Method 3: White Crayon Invisible Ink. Use a white crayon to write or draw your secret message on white paper. Press firmly so the crayon wax goes onto the paper, even though you can't see it well. To reveal the message, paint over the entire paper with watercolor paint, food coloring mixed with water, or even diluted juice. The waxy crayon marks will resist the liquid and your message will show up clearly against the colored background.
  4. Safety Tips for All Methods. Always have an adult help when using heat sources like ovens, irons, or hot light bulbs. Work in a well-ventilated area and protect surfaces with newspaper or paper towels. Wash hands after handling any materials. Never put paper directly on a hot stove or open flame. If using an oven, set it to the lowest temperature and watch carefully to prevent the paper from browning too much or catching fire.