(Dissolving Tips) Your Bath Bomb is Gone in 5 Minutes!


Taking a bath can be a relaxing and rejuvenating experience. Dropping a bath bomb into the water to add color, scent, and/or various cosmetic ingredients can make it even better. Not only can you personalize the hue and fragrance of your bath, but you can also purchase bath bombs designed to soften or soothe your sensitive skin. But how fast do bath bombs dissolve?

A well-constructed bath bomb of 2-inch diameter, weighing around 80g will take 6-8 minutes to completely dissolve once the active ingredients are placed in warm water, leaving your bathwater colored, salted, and smelling great.

Bath bombs are usually spherical and are small enough to fit in the palm of your hand. They are composed of dry ingredients that have been packed together tightly and, once in contact with your bath water, will dissolve and melt, providing the benefits and features promised on the package. 

Let’s find out more about the dissolving process and how you can change it when making your own DIY Bath Bombs

How do bath bombs dissolve?

When dry, bath bombs look similar to hard soap and can come in a variety of shapes and sizes and are a great alternative to bubble bath.

When a bath bomb is placed in water, they fizz, bubble, and dissolve. How does that happen?

Simply put, it’s chemistry! A chemical reaction between the ingredients in the bath bomb [citric acid and sodium bicarbonate] and the water is what causes the solid bath product to break down with an amusing fizzle over time.

The two basic ingredients of bath bomb mixture are baking soda and citric acid. Both of these are fairly accessible and inexpensive to purchase, which is why making homemade bath bombs is considered both a fun, easy, and safe activity.

When baking soda and citric acid are combined and then placed in a hot bath, a chemical reaction produces carbon dioxide bubbles. Hence, the FIZZ!

You can make a bath bomb recipe that fizzes without citric acid too.

How fast do bath bombs dissolve?

Bath bombs dissolve at various rates depending on their size and ingredients.

If you purchase a typical bath bomb from a mass-producing cosmetic company, it will generally take a few minutes to dissolve completely into your bathwater. 

However, if you make your own in a bath bomb mold at home, the speed at which the bath bombs dissolve can pretty much be entirely up to you.

How is that possible? Most recipes for homemade bath bombs also include cornstarch, a dry ingredient that acts as a filler for the bath bomb and is mixed in with the baking soda and citric acid.

Controlling the amount of cornstarch that you include in your homemade bath bombs will have a significant effect on how fast your bath bomb dissolves, as well as how many bubbles are produced when the chemical reaction occurs. 

You can also use an ice cube tray to make smaller embeds to give your bath bomb special effects, and this doesn’t affect the dissolving time at all

How does cornstarch affect the speed of dissolving?

Baking soda is a base and citric acid is an acid. When combined and added to water, a chemical reaction occurs. However, this chemical reaction is harmless and usually only results in mild fizzing, since baking soda and citric acid are fairly weak compounds.

Controlling the amount of cornstarch you use as a filler between the two reactors will allow you to determine how much the bath bomb will fizz, as well as how fast it will dissolve. It’s all about getting the correct ratio of cornstarch to baking soda and citric acid, which depends almost entirely on what kind of result you want to get out of your homemade bath bomb.

Using a higher ratio of cornstarch to baking soda and citric acid will weaken the compounds’ ability to react with each other. Thus, when you place the bath bomb in the water, there will be less fizzing. It will also take much longer for the bath bomb to dissolve.

Putting less cornstarch into the bath bomb ingredients and more baking soda and citric acid (but never more than what is safely recommended) will result in a bath bomb that creates more bubbles, but dissolves much faster.

In short, it’s up to you to decide what you want from your bath bomb fizz. It might take some experimentation to perfect your recipe’s ratio, but that’s the fun of it. 

What else can affect how fast bath bombs dissolve?

Other than the ingredients themselves, there are a few other factors to consider when determining how fast a common bath bomb might dissolve.

Firstly, as mentioned briefly above, the size of the bath bomb can contribute to the speed of dissolution.

This is fairly intuitive: the larger the bath bomb, the longer it will take to dissolve. On the other hand, smaller bath bombs tend to dissolve much faster.

Another important thing to take into account is the temperature of the water. Hot water causes the base and acid (baking soda and citric acid) to react more quickly and efficiently. Not only will warmer bath temperatures ensure a satisfactory dissolving speed, but it will also allow for more fizzing and bubbles to occur and enhance your bath time experience.

Cold water will still allow the chemical reaction to occur, but there will be less fizzing as the bath bomb dissolves. It isn’t often that people want to jump in a cold bathtub though, so this is usually not something to worry about when making your own homemade bath bombs. 

Related Questions

Here are a couple of questions that also come up that may not be covered fully above

How can you make a bath bomb dissolve faster?

The best way to make a bath bomb dissolve quicker is to crush it a little once softening in the bathwater. This will increase the overall surface area and the chemical reaction will take place over a greater mass of the ingredients as water comes into contact.

If looking to make it dissolve quicker in a natural way, then check out the ingredient suggestions in the main article.

How long do you sit in the bathtub with a bath bomb?

30 minutes would be the maximum time you would want to sit in a bath with bath bomb. Even at that length, especially in a hot tub, you would need some water close by to keep hydrated so as not to get a headache after exiting. 20 minutes would be the ideal amount of time to stay in the bath with your bath bomb.

Do I need to Rinse off after a bath bomb?

If using a colored bath bomb or one with glitter in, you might consider rinsing off after the bath. It sort of makes the bath bomb pointless tho, so, take a view on how you feel after and make a call then.

Bomb Guru

A bathbomb enthusiast who happened to be in the birthplace of bath bombs as they were born. My passion remains to this day

Recent Posts