There are few things more satisfying than dropping a bath bomb into your tub and watching it immediately fizz up, distributing cheerful color and relaxing scents throughout the water. But how does it do this? If you’ve ever wondered about the science behind bath bombs, we can tell you the secret: what you’re seeing is a chemical reaction between two ingredients that only occurs when they’re exposed to water.

The science behind bath bombs

Typically, there are two active ingredients in bath bombs: baking soda and citric acid. Citric acid is found in citrus fruits, but also comes in a powdered form that’s used in cooking and beyond. In their powdered forms, citric acid and baking soda are inert. When they come into contact with water, however, a chemical reaction is triggered.

As the two ingredients hit the water, they form sodium citrate and carbon dioxide, which is responsible for the bubbles. In turn, the bubbles help distribute the dyes and perfumes evenly throughout the water. As the bubbles pop, fragrance is released into the air, which is why you can readily smell their scent as soon as you drop the bomb in the water.

What else is in bath bombs?

Bath bombs have more ingredients than just the active ones, however—they often include a softening agent, such as an oil or butter, dyes (for color) and essential oils or perfumes. Depending on the maker and their objective, you might find that a bath bomb includes corn starch, which slows the chemical reaction. Epsom salts—said to promote muscle relaxation, among other effects—are another popular addition. Some are made with dissolvable glitter and confetti, while others choose to embed trinkets in theirs for an extra surprise.

You can easily make your own bath bombs by purchasing baking soda, citric acid, your additional ingredients of choice and a bath bomb mold. You’ll mix the powders together, moisten them enough to stick and then scoop them into a mold to let dry. Tutorials are available online—the key is to pick natural ingredients and non-staining dyes that will make the bath experience feel luxurious without leaving a big mess behind.

Love bath bombs, but don’t want to make your own? At Soaps & Scents, our bath bombs are made with a combination of baking soda, citric acid and almond, shea and cocoa butter. All our products are scented with natural fragrance or essential oils. They are colored with cosmetic-grade colorants that will not stain skin (or your tub) and weigh in at a hefty 5 ounces apiece.

Soaps & Scents has mastered bath bomb science and is proud to make all of our bath and home products in small batches, by hand. If artificial scents and ingredients make your skin itch, try our products. We offer everything from bar soap and bath bombs to body scrubs, linen sprays and candles. Call or come see us today to find out why our customers keep coming back—we look forward to seeing you soon!