Common Bath Bomb Ingredients: Everything You Need To Know!

by | DIY & Craft, Unwind

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Common Bath Bomb Ingredients:

Discussing common bath bomb ingredients and additives will help finally bring your project to life.

common bath bomb ingredients

Like with any project or recipe, to get the most out of the ingredients, it’s best to understand them and what they contribute to the final product.

That being said, many think making bath bombs is a breeze. Throw together a few ingredients in a mold, and their you have it. If you’ve made bath bombs, you’d know it’s not quite that simple.

Furthermore, the more ingredients you add to get a desired effect or aesthetic, the more crucial it is that you understand them and what specific ingredients add to the end creation.

Here, we’ll delve into more detail about common bath bomb ingredients and their impact.


Baking Soda (Sodium Bicarbonate):

baking soda for bath bombs

A staple in any bath bomb is baking soda or sodium bicarbonate. An alkaline white powder, and probably the most well known ingredient off the list. Baking soda is essential to making a successful bath bomb.

A common ingredient seen in baking, it is also well known for it’s use in many cleaning products, as well as things like toothpaste.

When purchasing any ingredient for a bath bomb, it’s also logical to choose reputable brands like Arm and Hammer. Afterall, these ingredients will make up a product that you or potentially even a customer will have in contact with their skin.

We choose baking soda with fine granules. the less clumpy these ingredients, the smoother final product. Baking soda is soluble in water and composed of sodium and bicarbonate ions.

Citric Acid:


citric acid in bath bombs

Potentially a less well known ingredient, in general, to baking soda is citric acid. This fine white powder is known to be used as a food preservative, amongst many other things.

Citric acid is an essential ingredient for success in bath bombs (if you want a great fizz). When combined with baking soda and placed in water, helps to achieve the fizzing reaction.

Now you can also use milk powder and certain other ingredients. However, to get the best fizz you need citric acid.

Citric acid is natural in fruits and is a weak organic tricarboxylic acid. Like with baking soda, you’ll want this in the finest powder you can find.

We buy our citric acid right from or in bulk. It’s inexpensive and you can find many reputable brands.


cornstarch for bath bombs

Many bath bomb makers include cornstarch on their list of essentials. However, it may depend on what other ingredients you’ve added or the goal of your end product.

Corn starch is said to act as an additional skin softener. With that being said, we’ve never noticed that much difference with or without it, from that perspective.

With that said, corn starch does in fact act a “buffer” if you will, between baking soda and citric acid. Meaning, it helps slow down the fizzing reaction.

Additionally, cornstarch can help a bath bomb float in water.

Substitutions for cornstarch include:

  • Arrowroot powder
  • Tapioca starch

Cream of Tartar (Potassium Bitartrate)

cream of tartar in bath bombs

Some believe this can be a “substitute” in a way to citric acid. However, using it in place of citric acid leads to FAR LESS fizzing action.

Cream of tartar, which you’ll find in many baking recipes, can be used in a bath bomb as a hardening agent.

Usually the end product is not quite as hard as if you used kaolin clay, however.

Polysorbate 80 (emulsifier):

Some believe that you don’t need an emulsifier in a bath bomb. However, an emulsifier like polysorbate 80 helps to mix any oils you have with water.

This includes any fragrance oils or carrier oils you likely have used. Additionally, colorants like mica’s and lakes are insoluble in water as well. Polysorbate 80 helps to disperse these colorants in water.

Without it, oils, mica’s, lakes can leave a nasty looking ring around the bathtub. A good rule of thumb is to use about half the amount of polysorbate 80 then your carrier oil. So if you use 10grams of oils, add 5 grams to your recipe of an emulsifier.

Kaolin Clay:

kaolin clay in bath bombs

Some clay’s are better then others. This additive serves multiple purposes. Firstly, kaolin clay is skin-safe and great to soak in for it’s skin softening effect. It has a detoxifying effect.

Secondly, it helps draw moisture out of your bath bomb and make for a rock solid end product.

Things to be careful with when it comes to kaolin clay, specifically:

  • It will make your mixture dry much faster. Meaning you have to be even more precious with the addition of moisture in the mix, and molding.
  • It will increase the weight and density of the bath bomb. Meaning if you want your bath bomb to float, use sparingly.


carrier oils in bath bombs

Truly, talking about oils can be an entire post in of itself. Oils are another one of those ingredients that’s based on preference.

We typically use oils in our bath bombs. However, keep in mind oils can cause the bath tub or a clients bath tub to become slippery. Always use a warning label if selling.

Common oils you see in bath bombs included:

  • coconut oil (medium oil)
  • avocado oil (light oil)
  • grape-seed oil (light oil)
  • sunflower oil (medium oil)
  • olive oil (heavy)
  • sweet almond oil (light oil, *favorite*)

These oils add another softening and hydrating element to your bath bombs, leaving skin feeling silky smooth. A little oils, goes a long way.

Furthermore, there is also a difference between oils. For instance, some are light, some are medium and some are heavy.

While each of these categorize of oils serve a purpose, they can also effect the weight of your end bath bomb.


salts in bath bombs

Another common ingredient you will find in bath bombs are salts, like Epsom salt (magnesium sulfate) or Himalayan salt.

Salts contain known minerals that help to soften, and heal the skin. Epson salt helps to relax sore muscles. Like salt in the human body helps retain water, so can salt in a bath bomb.

What does this mean?

Simply, be careful the usage rate because it can pull in moisture from the air. In other words, your bath bomb can become to damp, leading to issues molding or in the “drying process”.

You can use fine sea salt or coarse, like Epsom salt.

Witch Hazel:

Unlike alcohol (which is great for humid climates) or water (which is great for dryer climates), witch hazel can be used in any climate.

Witch hazel water is a liquid distilled from dried leaves, and twigs from witch hazel tree.

Adding a few sprays of witch hazel to the mixture is generally the last step prior to molding.

Final Thoughts!

These are the most common ingredients you will see in bath bombs. Whether it is essential or not, may depend on your personal preference and/or recipe.

If you’d like to know more about aroma’s in bath bombs, we poseted an article on aromatherapy and essential oils that are commonly added to bath bombs..

Thanks for stopping by, be sure to share our posts on social media if you’d like.

Disclosure: This post may contain affiliate links. If you use them to purchase items, then we may earn a small commission. Hope you find something that you like!
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