How to Make Bath Bombs: The Fun Science Behind It

I love baths!

how to make bath bombs

Preparing a nice bath is more than just keeping myself clean. It is also a way for me to relax and pause from the busy world outside.

At Simply Earth, we have a LOT of bath recipes that incorporate the power of essential oils and other natural ingredients to level up your bath experience. One of my (and the kids’) favorite bath recipes is bath bombs!

Bath bombs are fun and fizzy. Did you know that commercial bath bombs contain ingredients like synthetic fragrances and dyes? Luckily, you can make your own using essential oils and natural ingredients.

Bath bombs might look complicated, but they’re easy and fun to make. This means there’s no need to buy bath bombs from the store! Today, we’ll learn how to make bath bombs that are super safe, using only natural ingredients. But first, let’s get to know the science behind bath bombs.

The Science Behind Bath Bombs

how to make bath bombs

Bath bombs have three main ingredients: baking soda, citric acid, and cornstarch. Each of these ingredients works together for that fun fizz that’s unique to the product.

Baking soda, or sodium bicarbonate, with the chemical formula NaHCO3, has positively charged sodium (Na+) that quickly breaks apart from negatively charged bicarbonate (HCO3-) when added to water.

Also, a single hydrogen ion (H+) separates from the citric acid molecule. This positively charged hydrogen forms a bond with the negatively charged bicarbonate. This reaction happens very quickly and forms carbon dioxide (CO2) as an end product. Because carbon dioxide is a gas, it forms small bubbles in the water, hence the fizz.

Essential oils or fragrance oils are usually added to bath bombs, and the aroma is released into the air through the carbon dioxide bubbles.

What does the cornstarch do? It slows down the whole process, so you can enjoy it longer!

How To Make Bath Bombs

How to Make Bath Bombs: The Fun Science Behind It

BASIC Ingredients

  • ¼ Cup Baking Soda

  • 2 Tbsp Citric Acid

  • ¼ Cup Cornstarch

  • Bath bomb mold

  • Optional Ingredients:
  • Essential Oils – for aroma and added benefits

  • Carrier Oil – to dilute the essential oils

  • Isopropyl alcohol or witch hazel

  • Mica Powder – for color

  • Epsom salt, Milk powder, etc. – for added benefits to the skin

  • Small Toy or other accessories – for styling


  • In a bowl, mix all dry ingredients until they are well combined.
  • Mix the carrier oil and essential oil in a separate small bowl.
  • Add the oil mixture to your dry ingredients and whisk together until there are no clumps.
  • Spray in isopropyl alcohol (or witch hazel) and stir. Repeat until the mixture creates a clump when you squeeze it into your hand.
  • Add citric acid and stir.
  • Gently press your bath bomb mixture into each half of your mold. Overfill the mold so the mixture creates hills in each half of the bath bomb. Push mold together. Carefully remove it from the mold and set it out to dry.
  • Design bath bomb accordingly.

Indeed, bath bombs are highly customizable. You can play around with the color, shape, and aroma. Choose from our high-quality, pure essential oils to find something that matches your preferred scent and aromatic benefits.

Simply Earth Bath Bomb Recipes

how to make bath bombs

Have Some Fun In The Tub

Bath bombs are a fun and easy way to enjoy your bath time. But, what makes them fizz and bubble? And how can you make your own at home? In this post, we’ve answered all of those questions and more. So, gather up your ingredients, put on some music, and get ready to have some fun in the tub! How do you like to relax in the bath? Do you add bubbles or bath salts? We’d love to hear about it on social media with @fromsimplyearth and in the comments below!

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