Write an invisible message with flour and water and make it appear with iodine. Then use lemon to make it disappear again.
- A few drops of lemon juice
- 1 tablespoon flour (15 ml)
- 2 oz. of water (60 ml)
- cotton swabs
- a paper towel
- a few drops of iodine
What to do:
Mix 2 ounces of water with a tablespoon of flour. Write your message on the paper towel with a swab. When the message dries, it will be invisible. When you are ready to read it, use a swab to apply a few drops of iodine. Your message will appear in blue-black. Next, dab on a few drops of lemon.
Your message disappears.
The iodine reacts with the flour, a starch, to form a new compound that appears as blue-black. When you apply the lemon juice, the ascorbic acid (Vitamin C) of the lemon combines with the iodine to make a new colorless compound. So, if you spill iodine on anything, you can use lemon juice to remove it. It also removes ink, mildew, and rust stains-from paper and cloth..
Be careful not to get the lemon juice or vinegar in your eyes, it will burn. Don't taste. Iodine is poisonous.