How to Make Invisible Ink

If you think pesky spies are afoot and don't want them reading your letters or grocery lists, it's easy to make invisible ink. Once the ink is dry, your message will look like an ordinary blank piece of paper. Only those who know how to reveal the message will see it. Follow these steps for three different methods for making invisible ink.

Things You'll Need

• A heat source such as a light bulb for the lemon juice or baking soda method
• Lemon juice or baking soda or cornstarch and iodine
• A small bowl or other container to hold the ink
• A cotton swab, toothpick, paintbrush or toothbrush to use as a pen
• Plain white paper

Instructions

Make Invisible Ink with Lemon Juice

1. Get some lemon juice and put it in a small bowl or other container. You can squeeze a lemon or buy some in a bottle.

2. Write a message with the lemon juice on a plain white piece of paper. You can use a cotton swab, toothpick, paintbrush or toothbrush as a pen.

3. Let the paper dry completely.

4. Heat the paper up by holding it near a light bulb or other heat source.

5. Read the message which should appear in a pale tan or brown color.

Make Invisible Ink with Baking Soda

1. Mix baking soda and water in a small bowl or other container. You want to use equal amounts of both.

2. Write a message with the baking soda mixture on a plain white piece of paper. You can use a cotton swab, toothpick, paintbrush or toothbrush as a pen.

3. Let the paper dry completely.

4. Heat the paper up by holding it near a light bulb or other heat source.

5. Read the message which should appear in a brown color.

Make Invisible Ink with Corn Starch

1. Heat 2 tbsp. corn starch with 1 tbsp. water in a small pan. Stir until it's well dissolved.

2. Write a message with the corn starch mixture on a plain white piece of paper. You can use a cotton swab, toothpick, paintbrush or toothbrush as a pen.

3. Let the paper dry completely.

4. Make an iodine solution of 1 part iodine to 10 parts water. You could use 1 tsp. iodine and 10 tsp. water as a recipe.

5. Paint the paper with the iodine solution using a brush or cotton ball. Your message will appear in purple.

Tips & Warnings

• This can be done with other fruit juices. Some suggest onion juice too, if you can figure out how to squeeze an onion.

• An alternative, yet messy way of reading the message is to paint the paper with purple grape juice instead of applying heat.

• You don't have to heat up the water and cornstarch over the stove, but it works better if you do.

• Be careful when heating up the paper. If it gets too hot it might catch on fire.