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When making the most of your bath time, a bath bomb is a penultimate addition. Bath bombs can add a desirable, luxurious element to your bath water. Yet, they also provide the most fun and relaxing of pampering sessions.
Here, The Bathroom Showroom explores the world of bath bombs, from their initial creation through to the benefits these fantastic toiletries offer when soaking in the tub.

Who Invented Bath Bombs

The bath bomb was invented by Mo Constantine. Originally created in her garden shed, Mo is the co-founder and product investor for the popular British company, Lush. 

What Is a Bath Bomb?

A bath bomb is a solid, often spherical, toiletry item designed to dissolve and effervesce when dropped into bathwater. 
Made using a good balance of bicarbonates and a weak acid,  when placed in water, the ingredients of a bath bomb will react. The result is a bubble and fizz effect. This reaction also helps to disperse other ingredients, such as oils, fragrances, and colorants, throughout the water.

What Is a Bath Bomb Made Of?

The core of every bath bomb consists of two primary dry ingredients that are unreactive until they're exposed to water:
  • Sodium Bicarbonate (NaHCO3​): Commonly known as baking soda, this is a weak base.
  • Citric Acid (C6​H8​O7​): This is a weak acid typically derived from citrus fruits.
When these two ingredients come into contact with water, a chemical reaction takes place. The water acts as a medium, allowing the citric acid and sodium bicarbonate to react and produce carbon dioxide (CO2​) gas, which creates the fizzing effect.
As well as these two essential ingredients, bath bombs are made with a variety of other components to provide different sensory experiences and benefits:
  • Binders: Ingredients like cornstarch, arrowroot powder, or kaolin clay are often added to help the bath bomb hold its shape and to slow down the fizzing reaction, making the experience last longer.
  • Essential Oils or Fragrance Oils: These are added to provide the pleasant scents that are released into the steam and bathwater.
  • Colorants: Dyes, mica powders, or other colourants are used to turn the bathwater into vibrant colors.
  • Moisturisers: Oils and butters such as shea butter, cocoa butter, coconut oil, or almond oil are included to help moisturise and soften the skin.
  • Other Additives: Depending on the desired effect, bath bombs can also contain glitter, dried flower petals, Epsom salts for muscle relaxation, or sodium lauryl sulfoacetate (SLSA) to create a foamy, bubbly effect.

How Do Bath Bombs Work?

When a bath bomb is dropped into water, a chemical reaction occurs between two key ingredients: a weak acid, typically citric acid (C6​H8​O7​), and a weak base, or alkali, which is usually sodium bicarbonate (NaHCO3​), also known as baking soda. These two ingredients are stable when dry, but the water acts as a catalyst, dissolving them and allowing them to react.
The reaction is a form of acid-base neutralisation that produces sodium citrate, water, and, most importantly, carbon dioxide (CO2​) gas. This gas is what creates the characteristic fizzing and bubbling effect. The equation for this reaction is:
C6​H8​O7​(aq)+3NaHCO3​(aq)→Na3​C6​H5​O7​(aq)+3H2​O(l)+3CO2​(g)
The released carbon dioxide bubbles help to break up the bath bomb, allowing other ingredients, such as essential oils, fragrances, and colourants, to disperse into the water. This process transforms the bath into a more visually and aromatically pleasing experience.

The Chemistry Behind Bath Bombs

This fascinating video, ‘The Chemistry Behind Bath Bombs’ explains the chemical reaction that causes the fizzing of bath bombs.

What Types of Bath Bombs Are Available?

Different types of bath bombs offer a variety of experiences and benefits, catering to different preferences and needs. Here's a breakdown of some common types:
Vegan Bath Bombs
Vegan bath bombs are made without any animal-derived ingredients. This means they’re free from common non-vegan additives like milk, honey, beeswax, or lanolin.
For their ingredients, vegan bath bombs use plant-based ingredients such as essential oils, botanical extracts, and butters like Shea butter or cocoa butter.
People who follow a vegan lifestyle or those who want to avoid animal products in their cosmetics will opt for these. Many vegan bath bombs are also cruelty-free, meaning they are not tested on animals.
Organic Bath Bombs
Organic bath bombs are made with ingredients that are certified as organic, meaning they are grown and processed without synthetic pesticides, herbicides, or GMOs.
They often feature organic versions of common bath bomb ingredients, such as citric acid, baking soda, and essential oils.
A popular choice for those looking for a more "natural" product, organic bath bombs are free from harsh chemicals, synthetic fragrances, and artificial dyes. They are generally gentler on the skin and better for the environment.
Glitter Bath Bombs
Glitter bath bombs are designed to add a shimmering, sparkly effect to the bathwater.
As they contain glitter, they can be made from a variety of materials, so it’s important to look for cosmetic-grade glitter that’s safe for skin. However, some glitter can be abrasive and may cause skin irritation, especially in sensitive areas.
The primary appeal of glitter bombs is undeniably the visual spectacle they create in the bath. They’re often used for a fun, festive, or luxurious bathing experience. But, it's important to note that many glitters are made of plastic and are not biodegradable, posing an environmental concern.
Foaming Bombs (Bubble Bombs)
Unlike traditional bath bombs that primarily fizz, foaming bombs create a layer of bubbles on top of the water, similar to a bubble bath.
These bath bombs contain a combination of the standard citric acid and sodium bicarbonate, but also include an additional ingredient, typically sodium lauryl sulfoacetate (SLSA), which is a gentle, coconut-derived surfactant that creates foam.
Foaming bombs are ideal for people who enjoy the experience of a bubble bath combined with the colour and aroma release of a bath bomb. They offer a richer, more luxurious feel to the water.
Health-Benefit Bath Bombs
There is a broad category of bath bombs that are formulated with specific ingredients to address particular skin or wellness needs. Some fantastic examples include:
  • Moisturising Bath Bombs: These are packed with hydrating ingredients like Shea butter, cocoa butter, coconut oil, almond oil, or jojoba oil. As the bath bomb dissolves, these butters and oils melt, leaving the skin feeling soft and supple.
  • Aromatherapy Bath Bombs: These are infused with pure essential oils like lavender for relaxation, eucalyptus for sinus relief, or peppermint for an invigorating sensation.
  • Soothing Bath Bombs: Some bath bombs contain ingredients like Epsom salt (magnesium sulfate) or kaolin clay to help soothe sore muscles or detoxify the skin.
Sensitive Skin Bath Bombs
These bath bombs are specifically designed for people with sensitive skin, eczema, or other skin conditions. 
Often boasting a very minimal ingredient list, bath bombs for sensitive skin avoid common irritants like synthetic dyes, perfumes, and strong fragrances. They may be unscented or use only a small amount of a gentle essential oil. Key ingredients often include simple, moisturising butters like cocoa butter.
Offering the fun and relaxation of a bath bomb experience, these bath bomb types are without the risk of irritation, itching, or rashes that can be caused by dyes and fragrances.

How Do I Use a Bath Bomb?

Using a bath bomb is a simple and enjoyable way to transform your bath into a relaxing, multi-sensory experience. Here's a step-by-step guide to get the most out of your bath bomb.
1. Fill Your Tub with Water
The first step is to fill your bathtub with water. The temperature of your bath water is a matter of personal preference, but warm water is recommended. It not only makes for a more comfortable soak but also helps the bath bomb dissolve properly, especially if it contains moisturising ingredients like cocoa or shea butter.
2. Unwrap the Bath Bomb
Remove all the packaging from the bath bomb. Many bath bombs are wrapped in plastic to protect them from moisture, so make sure to take it off completely before use.
3. Drop It In
Once your tub is full, drop the bath bomb into the water. This is the main event! The bath bomb will immediately begin to fizz, bubble, and spin, releasing its colours, scents, and other ingredients into the water. You can place it in the centre of the tub or hold it under the running water for a different effect.
4. Watch and Relax
This is the fun part. Watch as the bath bomb dissolves, creating a vibrant display of colour and a fragrant aroma that fills the bathroom. The fizzing reaction typically lasts for several minutes. Once it has fully dissolved, the water will be coloured and infused with the bath bomb's properties.
5. Soak and Enjoy
Now you can get into the tub and enjoy your customised bath. Soak for as long as you like, breathing in the aroma and letting the oils and butters soften your skin.
Tips for an Enhanced Experience
  • Set the Mood: Enhance your relaxation by dimming the lights, lighting some candles, and playing some calming music.
  • Split the Bomb: If you have a particularly large bath bomb, you can cut it in half carefully with a serrated knife while it's dry to get two uses out of it.
  • Clean Up: Some bath bombs with very vibrant dyes or glitter may leave a slight ring or residue in the tub. A quick rinse or wipe-down after you drain the water can prevent any staining.

Commonly Asked Questions About Bath Bombs

Can I Make My Own Bath Bombs?
You can make your very own bath bombs at home. This is a popular DIY project and one that’s both fun and cost-effective. A relatively simple process, making your own bath bombs allows you to customise with your favourite colors, scents, and ingredients.
What Ingredients Do I Need to Make My Own Bath Bombs?
There are some essential ingredients you’ll need to create the perfect bath bomb at home. These include:
  • Baking Soda (NaHCO3​): The primary alkaline ingredient.
  • Citric Acid (C6​H8​O7​): The acidic ingredient that reacts with the baking soda to create the fizz. This is a key component for the bath bomb to work.
  • Cornstarch or Arrowroot Powder: This acts as a binder, helping the bath bomb hold its shape and slowing down the fizzing reaction for a longer-lasting effect.
  • Carrier Oil: Oils like coconut, almond, or jojoba oil help to moisturise the skin and bind the ingredients together.
  • Essential Oils or Fragrance Oils: These provide the scent. You can choose from a wide variety of essential oils for different aromatherapy benefits.
  • Colourant: Food colouring, mica powders, or soap dyes are used to add colour to the bath bomb and the water.
How Do I Make My Own Bath Bomb?
  1. Mix the Dry Ingredients: In a large bowl, whisk together the baking soda, citric acid, and cornstarch. It's important to mix these thoroughly to ensure a consistent reaction.
  2. Mix the Wet Ingredients: In a separate, smaller container, combine your carrier oil, essential oil, and any liquid colourants.
  3. Combine Wet and Dry: Slowly add the liquid mixture to the dry ingredients while whisking or using your hands to mix. This is the most crucial step—if you add the liquid too quickly, the mixture will start to fizz and your bath bomb will be ruined. The goal is to achieve a consistency similar to damp sand that holds its shape when you squeeze it.
  4. Mould and Pack: Pack the mixture tightly into your chosen moulds. You can use specific bath bomb moulds, or get creative with household items like muffin tins or silicone moulds. Overfill each half of a spherical mould and then press the two halves together firmly.
  5. Dry: Let the bath bombs dry and harden. This can take anywhere from 12 to 48 hours, depending on the humidity of your environment. It's best to leave them in a cool, dry place, away from any moisture.
  6. Store: Once completely dry, store your bath bombs in an airtight container or wrap them in plastic wrap to protect them from humidity, which can prematurely activate the fizzing reaction.
Do Bath Bombs Expire?
Though bath bombs don’t spoil like food, they will expire, losing their potency and effectiveness over time. It’s the key ingredient in a bath bomb that degrades, which affects their overall performance.

Bath Bombs offer a Wealth of Bathroom Inspiration

If you’re looking for ways to mix up your bath times, a bath bomb is the perfect skin-friendly and bath-friendly solution. Whether it’s an energising, spa-like, or anxiety-reducing bath time you’re after, there’s a bath bomb to suit all your needs. 
For more information on creating the perfect space, book an appointment with The Bathroom Showroom. Experts in all things bathrooms, we can help turn your dream bathroom into a reality.