1/Squeeze the juice of half of a lemon into a bowl.
2/Add a few drops of water. Stir the juice and water with a spoon.
3/Dip a cotton swab into the lemon juice mixture and write a message on a piece of white paper. A feather, a toothpick, a fountain pen, a paintbrush or a calligraphy pen will also work in place of the cotton swab.
4/Allow the invisible ink to dry. As the ink dries, your message will disappear.
5/Hold the paper that contains your invisible ink message over a light bulb or flame/candle. Keep the paper near the bulb or flame/candle until the message reappears. Be careful not to put the paper too close if you are using a flame/candle.
6/Invisible ink is ok.