Invisible Magic: Make your own secret messages and drawings!

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Imagine being in an intense situation where you need to strategize with your team that is far away, but have no cell phones, email, or internet to talk to them. That’s the intense situation many found themselves in during war hundreds of years ago, who relied on invisible ink to secretly share war tactics and information.

In today’s experiment, we will be creating our own invisible ink.

Creating invisible ink can be done without extreme heat! Turmeric, nature’s pH indicator, changes the invisible baking soda (a base) ink to a very bright color, exposing your secret message.

So put your spy glasses on and create your own secret message!

How to make the Invisible Magic science experiment

Supplies you will need

For this experiment, you will need the following:

Baking soda (1/4 cup )
Water (1/4 cup)
Q-tip or small paintbrush
Paper (a heavier paper is best)
Turmeric
Rubbing alcohol (1/4 cup) – I used a hand sanitizing gel because I had it handy, but note that the alcohol level is 70%

Supplies needed for the Invisible Magic invisible ink science experiment

Before you start

Turmeric can easily stain surfaces (and little hands), so place down a towel that you don’t mind getting yellow!

Instructions

Here is how to do this experiment with your child:

Step 1: Mix baking soda and water

In a small dish, mix 1/4 cup of baking soda with 1/4 cup of water.

The baking soda will settle to the bottom of the bowl, but you can just dip the Q-tip (in the next step) into the solution to pick up some baking soda.

Pour baking soda into 1/4 cup of water and mix

Step 2: Write your message

Dip your Q-tip or small paintbrush into the baking soda mixture and write your message on a piece of paper.

It can be words or even some fun art. Get creative!

Allow this to dry for about 10-15 minutes.

Writing with the baking soda and water mixture

Step 3: Mix turmeric and alcohol to reveal message

Mix 1/4 cup of alcohol with turmeric. The consistency should be close to a very runny paste.

Using your small paintbrush, brush the turmeric mixture over the paper to reveal the message.

Mixing turmeric and alcohol to make a runny paste

Painting the turmeric mixture over the paper

The science behind the Invisible Magic experiment

This experiment teaches:

The history of invisible ink
pH levels
How invisible ink is used today

How it works

The invisible ink experiment works by first writing a message on a piece of paper using a baking soda and water mixture. The message dries and it appears that there is nothing written on the piece of paper.

Using the turmeric and alcohol mixture, we paint over the message to reveal what was written in baking soda.

Since turmeric is a natural pH indicator and baking soda has a higher pH level, it makes the message appear in a different color than the yellow “paint” of the turmeric.

The history of invisible ink

The first record of invisible ink came from Pliny the Elder over 2,000 years ago. He used milk of the tithymalus plant as the “ink” and sprinkled ashes on the dried ink to expose the message.

Since then, there have been several different concoctions that produce these encripted messages, including ferrous sulfate and water during the Revolutionary War. These secret messages were used to secretly communicate war tactics, including between spies!

pH levels

If you have ever tried to test your pool water to see how much chlorine or salt you should put in? If so, you were checking the pH levels of your pool to ensure it’s balanaced properly!

In our case, the spice turmeric is actually a natural pH indicator.

When we paint the turmeric and alcohol mixture over the dried baking soda message, the turmeric exposes the pH level of the baking soda with a deep red color.

What are some other real-life examples of how pH is tested?

Aquariums
Food (to check for bacteria growth)
Beverages (to check for acidity)
Wastewater treatment
When pH of our mouths reduces, it means our teeth are decaying
The acidity of plant fertilizers

How is invisible ink used today?

There are other types of invisible ink out there, ones that do not necessarily require a turmeric mixture to reveal something.

For example, there is an invisible ink used today that requires UV light to expose a message or picture. That type of invisible ink is used for tickets for readmission to an event, lottery tickets, or to mark items in case of theft.