DIY Rainbow Bath Bomb Recipe

Kids love baths and our DIY Rainbow Bath Bomb recipe is a delightful way to make bath time even more amazing. They look beautiful, smell incredible, and adults will LOVE them too!

rainbow bath bombs pin

We love bath bombs for oh-so-many reasons!

They’re super easy to make, fun to use, and sell like hotcakes if you have a school fundraiser or want a little side business.

Plus, it’s a blast experimenting with different ways to make them.

If you’ve tried my glow-in-the-dark bath bombs, you know what I mean! 😁

Love crafts and easy DIY projects? Grab this mini activity book for more by clicking the image below – free! 👇

Click here to get your free mini-book of DIY activities for kids of all ages.

Well, we’ve been on a rainbow kick lately, so when the topic of bath bombs recently came up, fireworks started going off in my head! Why not try my hand at a rainbow bath bomb?!

That’s how new ideas are born, friends! 😂 

Now, I know I’m not the first person to make a rainbow bath bomb…and these are different from the fizzing cloud rainbow bath bombs that are everywhere on the internet. They’re better!

This rainbow bath bomb recipe is SUPER easy, affordable, and the kids will love to help make them (or make them by themselves!).

If you love rainbow activities and food, check out my Rainbow Jello Squares, Rainbow Walking Water Experiment, or Fruity Cocomelon Rainbow Popsicles.

rainbow bath bombs

Ingredients Needed For DIY Rainbow Bath Bomb Recipe

Here’s what you’ll need to make these easy rainbow bath bombs.

  • Baking Soda
  • Epsom Salts – excellent for the skin and muscles
  • Citric Acid – necessary to create the fizz in the bath bomb
  • Cornstarch – slows down the rate at which the ingredients dissolve
  • Almond Oil – helps give the bomb shape and adds moisture to the bath water
  • Water
  • Mica Powder – red, orange, yellow, green, blue and purple
  • Bath Bomb Molds – silicone or metal
  • Essential Oils – these are optional, but feel free to add up to 10 drops of any scent you prefer to make these bombs even MORE special.

I use Rocky Mountain Oils for all my essential oils needs – I’ve tried nearly every brand out there and paid out the wazoo for some that I hoped would be better quality. But I’ve have found these oils are the highest quality and BEST value! Read more about why I use Rocky Mountain Oils here.

recipe ingredients

How To Make DIY Rainbow Bath Bombs

Just follow this simple process to make your own rainbow bath bombs!

Step 1

In a large bowl, whisk the baking soda, Epsom salts, citric acid, and cornstarch until fully combined.

mixing dry ingredients together

Step 2

In a medium-sized jar, add almond oil and water (and essential oils, if you’re using them). Put the lid tightly on the jar and shake well.

mixing wet ingredients in a jar

Step 3

Now, very slowly pour the liquid mixture into the dry mixture. You must whisk the whole time so as not to activate the fizz. Stir well.

add wet ingredients to the dry ingredients

Step 4

In six small bowls, divide the mixture evenly.

Step 5

In each of the bowls, add a different color of mica powder and stir thoroughly.

bath bomb mixture in 6 different colors

Step 6

In half of the bath bomb molds, start layering the colors. Begin with red, next is yellow, and then orange.

filling molds
adding another layer to the mold
adding third color to bath bomb mold

Step 7

In the other half of the molds, layer the colors in the following order: green, blue, and purple. Overfill the mold with the third color. This is important for the next step.

Step 8

Press the two halves of the molds together and gently twist.

closed bath bomb mold

Step 9

Set the molds aside and allow them to sit for 4 – 6 hours.

Step 10

Carefully remove each rainbow bath bomb from its mold and allow them to sit so they continue setting. Then store in a plastic storage bag or airtight container.

rainbow bath bombs

Rainbow Bath Bomb Recipe Notes And Tips

  • Using a glass jar and bowls is ideal for preparing this recipe. The glass containers will not hold in oils and residue from the citric acid and epsom salts.
  • It is very important to allow the bath bomb to dry for NO less than 4 hours. Longer is better, if possible. If you remove the bath bomb from the mold before it is fully dried, it will crumble.

Love crafts and easy DIY projects? Grab this mini activity book for more by clicking the image below – free! 👇

Click here to get your free mini-book of DIY activities for kids of all ages.

Variations Of Rainbow Bath Bombs To Try

  • Use glow-in-the-dark mica powder for a fun twist!
  • Change up the colors of the mica powder. Use pastel colors and give the bath bombs for Easter or reds and greens for Christmas. These make PERFECT gifts and DIY items to sell!
  • Make your bombs unique by making different shapes such as hearts, stars, moons, seashells or whatever your heart desires. Simply get shaped bath bomb molds.
  • Add your preferred essential oil for that extra soothing scent as your Rainbow Bath Bomb dissolves.
rainbow bath bombs

Rainbow Bath Bomb FAQs

Here are some common questions about our Rainbow Bath Bombs recipe. If you don’t see your question below, please leave it in the comments so I can answer it!

Do bath bombs explode?

Bath bombs are really just a fancy version of bubble bath. Bath bombs do not actually ‘explode’. They fizz when they hit the water, causing a chemical reaction.

The combination of fizzy bubbles and salts is a great way to treat sore muscles. This makes bath time tons more fun for the kiddos and likely a relaxing evening for mom. 😉

Is it OK to use a Rainbow Bath Bomb everyday?

It is recommended that you do not use a bath bomb every day. It is possible that some of the ingredients could cause skin irritation if used on a daily basis.

You can enjoy a bath bomb a couple of times a week, if desired. Come up with other ways to create a soothing bath experience, for example, light a candle, diffuse some essential oils, or listen to some relaxing music.

Why do bath bombs crack?

If the bath bomb is too dry, it will crumble or crack as they are being removed from the mold. And if it is too wet, the bath bomb will expand in the mold and crack.

You will know you have the proper consistency of bath bomb mixture when it can hold its form when pressed in a ball shape.

rainbow bath bomb

Do bath bombs actually do anything?

The ingredients in a bath bomb help to moisturize and soothe your skin. The bombs are made with emollients and softeners that are beneficial to your skin leaving it silky and soft.

Bath bombs are unique in their dual purpose of cleansing as well as pampering and soothing.

Why is my bath bomb not fizzing?

Citric acid is the ingredient that creates the fizz so you might need to try increasing the amount of citric acid. You could consider decreasing the amount of oil as well. Then store the bath bomb in a cool, dry location.

What is the purpose of cornstarch in bath bombs?

That’s a great question. Cornstarch has basically only one job in a bath bomb but it is a very important job. 😉

Cornstarch slows down the rate at which the citric acid and cornstarch dissolve. This means that the fizziness of the bath bomb will last 2 – 4 minutes rather than only a few seconds.

rainbow bath bomb

More Fun, Kid-Friendly DIY Projects And Activities To Try

If you love this rainbow bath bomb activities, try some of these other fun activities too!

Love crafts and easy DIY projects? Grab this mini activity book for more by clicking the image below – free! 👇

Click here to get your free mini-book of DIY activities for kids of all ages.
DIY Rainbow Bath Bombs

DIY Rainbow Bath Bombs


  • ½ cup baking soda
  • ¼ cup epsom salts
  • ¼ cup citric acid
  • ¼ cup cornstarch
  • 1 ½ tbsp sweet almond oil
  • 1 tsp water
  • ¼ tsp each of red, orange, yellow, green, blue, and purple mica powder
  • Bath bomb molds


  1. Add the baking soda, epsom salts, citric acid, and cornstarch to a large bowl, and use a whisk to stir the ingredients until they are fully combined.
  2. Add the sweet almond oil and water to a small jar with a lid and shake well.
  3. Very slowly add the liquid mixture to the dry mixture, while whisking the entire time, so you do not activate the fizz. Stir well.
  4. Divide the mixture evenly between 6 small bowls.
  5. Add one color of mica powder to each bowl, and stir well until the color is solid.
  6. Begin layering colors into the bath bomb molds. Red, yellow, then orange in one half; green, blue, then purple in the other half. Make sure to overfill the mold with the third color.
  7. Press the two halves together and lightly twist.
  8. Allow bath bombs to set in the molds for 4-6 hours, then you may remove them to finish setting.
  9. Store in an airtight container or bag.

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