Be a Secret Scientist: Make Edible, Invisible Ink!

3 08 2012

Have you ever wanted to send a secret message to someone? Have you heard about invisible ink?  Invisible ink is ink that cannot be seen until revealed with a secret trick.  If you want to make your own, edible, and invisible ink, follow the directions below!

To make your invisible ink message, you will need the following:

– a few small containers

– at least one of the following:
lemon, orange or grapefruit juice
sugar solution*
baking soda solution*
*(You can make the sugar and baking soda solution by mixing sugar or baking soda with a little bit of water until the water is saturated with the sugar or baking soda.)

– cotton swabs

– a piece of paper

– a heat source, such as a hair dryer, an electric iron, or an oven (set to a low heat, around 250 degrees, and check your message every few minutes!)

– a plastic tray

First, place your piece of white paper on the plastic tray.  Then, dip a cotton swab into one of your invisible inks, write your secret message on your piece of paper, and wait for the message to dry.  I used lemon juice, a sugar solution, and a baking soda solution for my invisible inks.

My wet inks!

Once the message has dried, put it under your heat source (a hair dryer or iron) and watch your message reveal itself!

After being heated, my messages were revealed!

What is the science behind your invisible ink message?

Well, what do all of the inks have in common? Lemon juice, orange juice, grapefruit juice, milk, sugar, and baking soda are all edible (they are all things that you can eat).  Now,  think about when you bake cookies for too long.  They turn brown or black.  Thus, when we  “bake” our edible inks, they become brown or black also!

My lemon juice became a light yellow and my baking soda solution turned a light brown.  My sugar solution didn’t show up very well, and I think it’s because I didn’t mix enough sugar into the water.  If you use the baking soda or sugar solution, make sure you use enough baking soda or sugar!

Which “ink” did you use? Did you try multiple inks? Which did you prefer?


Invisible Ink

3 08 2009



· Baking Soda

· Paper

· Water

· Light Bulb (for your heat source)

· Paintbrush or cotton swab

· Measuring Cup

· Purple grape juice


Here are two ways to experiment with your baking soda based Invisible Ink:

1) Mix equal parts water and baking soda.

2) Use a cotton swab or paintbrush to draw a picture or write a message on your paper using the baking soda solution.

3) Allow your invisible ink to dry.

4) One way to reveal your message or drawing is to hold your paper near the heat source, the light bulb. The baking soda will react with your heat source and turn brown, revealing your “invisible” drawing. Be careful when holding your paper up to the light bulb. Paper is flammable!

5) The second way to reveal your image is to paint over your invisible drawing with purple grape juice. The baking soda and grape juice with have an acid-based reaction and the invisible message will appear.