Chemistry in the Kitchen: Make Your Own Bubbles With Dish Soap

Everyone loves bubbles. They’re a favorite outdoor activity on a nice sunny day. We can chase them, run through clusters of them, and pop them. They flash with beautiful rainbow colors. Bubbles are great! 

Image Credit: Eduard / Istock / Getty Images

We have provided a great bubble recipe down below that involves one of the most common items in a kitchen: dish soap! But first, did you ever wonder what’s the science behind bubbles? What actually makes up a bubble? Why are they round? Why do they pop? What are the pretty rainbow colors? Let’s explore these questions.

What makes up a bubble?

Bubbles are made up of two things: soap and water. You can think of a bubble as a sandwich of sorts. The two pieces of “bread” consist of soap molecules (a group of atoms bonded together). The “meat” of the sandwich is a thin layer of water. The soap keeps the water safe and sound; for a while at least. Of course we can’t forget that the entire bubble sandwich encloses air.

A single soap bubble displaying the three layers that make up the “bubble sandwich”- soap on the top and bottom, and water in the middle. (Image credit: Pashminu, Wikimedia Commons)

Why are bubbles always round?  

Let’s say your bubble wand is shaped like a heart or star. When you create a bubble with your wand, it may stretch, but when you seal the bubble, it will not be shaped like a heart or star, but a round shape called a sphere. No matter what, a single bubble will always try to become a sphere. This is because the sphere is the smallest possible shape for the volume of air it contains. If a bubble had corners or edges, the soap would be stretched unevenly, and therefore would be less efficient because it requires more energy to achieve.

Single bubbles will always be a sphere shape. (Image credit: Brocken Inaglory, Wikimedia Commons)

Why do bubbles pop?

There are a few reasons why bubbles pop. The likely culprits are: 

• Water evaporation

• Strong winds

• Dryness. 

The sun plays a major role in evaporation as it changes water from a liquid to a gas or vapor. This causes bubbles to pop. Along with evaporation, wind is another bubble popper. Strong winds and sometimes gentle breezes can destroy a perfectly good bubble or even prevent bubbles from forming. Dry conditions are also a reason for bubbles popping. If the air, or any surface, like your finger, is dry, bubbles don’t stand a chance and will instantly pop. 

Here are some ways to create the perfect conditions for bubbles:

• Stay in the shade if possible

• Try blowing bubbles right after the sun sets

• Do not blow bubbles when it is windy out

• Right after a rainstorm is a good time to play with bubbles because the air is full of moisture

• Blow your bubbles in a wide open space so they will less likely run into dry objects

• Keep bubble tools (or hands) wet so your bubbles don’t accidentally pop 

Image credit: Fir0002/Flagstaffotos@gmail.com / Wikimedia Commons

What causes the rainbow colors to form on bubbles?

The beautiful collection of colors that you see on a bubble are light waves reflecting back to your eyes from the outer and inner soap layers. The light waves from the two layers interfere with each other. The interference can cause certain colors to appear dull or non-existent, while other colors appear more vibrant. The colors that you see in a bubble are called interference colors and what you see depends on the thickness (which constantly changes) of the soap and water layers. Because the layers constantly change, the colors constantly change, and no two bubbles will have the same color arrangement.         

A single light soap bubble photograph taken under macro photography. Light interference between the two soap layers causes amazing iridescent colors. (Image credit: Pashminu / Wikimedia Commons)

The Perfect Bubble Recipe

Now that you know a little science behind bubbles, you can easily make your own! The following recipe is just one way to make bubbles. 

Materials:

• 3 cups of water (distilled is best if you have some)

• 1 cup of liquid dish soap (Dawn or Joy brands work best)

• ½ cup of white corn syrup OR ½ cup of glycerin (these ingredients will slow down water evaporation and help build stronger bubbles)

• A container to keep your bubble solution in

Instructions:

1. Pour the water into your container 

2. Add the glycerin or corn syrup to the container and stir

3. Carefully pour and gently stir the dish soap into the container

4. For best results, let the bubble solution sit overnight  

5. You are now ready to blow some bubbles! Grab your bubble wands and get outside!

Want More Bubble Science?

To gain an even deeper understanding behind the science of bubbles, click here to join Physicist Dr. Helen Czerski as she takes you on a bubble-filled journey in the documentary: “The Science of Bubbles”. 

By Megan Goldsmith