Things You'll Need
Instructions
Write a misleading message on plain white paper using a regular pen or pencil. It can even be a silly note, story or poem. The purpose is to confuse enemies that might accidentally get their hands on it. Make sure that the ordinary ink dries completely before you begin using the invisible ink.
Pour some lemon juice into a small cup or bowl. Dip a toothpick into the juice and write your real message on the note with it. You can write in the margins at the top, bottom and sides of the sheet, and even in between the lines written with regular pencil or pen. At this point, you will probably still be able to see the words written with the juice. But when you're all done, only the authorized recipient will be able to read it.
Let the lemon juice dry completely. Just set the paper flat on a table top where it won't be moved around. Your message will begin to disappear as the juice dries. If writing is still visible after it has dried, add some water to the cup of lemon juice and try it again with a new paper and message.
Get a grownup to light a candle for you. Hold the message face-up over the flame to heat it, but not close enough to burn it. The lemon juice will darken when it's heated so that the invisible ink can now be read.