Unicorn Galaxy Bath Bomb Recipe and Science Lesson For Kids

Teach your kids some fascinating science with a lesson in how to make bath bombs! Kids love bath bombs, especially the spectacularly fun fizzy reaction in the bath. This makes it easy to get them also excited about the science behind the bath bomb fizz. Even better is when you come up with a fun bath bomb theme, like this Unicorn Galaxy Bath Bomb recipe!

Bath Bombs for Kids – Unicorn Galaxy

What you will discover in this article!

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Once you start making bath bombs you are going to find it is activity your kids ask to do over and over again. The creativity is amazing! Since it is also a fascinating chemistry experiment that erupts, even the most reluctant crafters and makers get excited about making bath bombs.

Best of all, I am saving a ton of money with my bath bomb loving kids!

THE STORY OF Unicorn Galaxy Bath Bombs

This bath bomb recipe came about because it was just plain messy fun and had a colourful galaxy like quality. Sometimes we get fancy and precise like when we made our original unicorn bath bombs. Other times we like to get crazy and have some fun!

The kids said these bath bombs looked like Unicorn Puke.

I like the term Unicorn Galaxy better. It’s more dignified.

But use whatever works best for you!

Unicorn Galaxy Bath Bomb Recipe

Ingredients and Supplies

2 cups baking soda
1 cup citric acid
1/4 cup kaolin clay
1/4 cup cream of tartar
1/3 cup melted coconut oil
2 teaspoons polysorbate 80
2 tablespoons melted kokum butter
10-20 drops of your favourite essential oil – we used rosemary essential oil
1-2 teaspoons each of purple, blue, pink, yellow & green mica colorant
1 tablespoon biodegradable cosmetic glitter*
Stainless steel bath bomb molds
Mini muffin tin (optional)
1 large mixing bowl
1 Microwave safe measuring cup
5 small bowls

*A NOTE ON GLITTER – Glitter has become very controversial due to the negative impacts on the environment, but I know many of you still love a little sparkle in your projects! When it comes to glitter, I believe it is always optional. None of my projects require it. But if you decide you do want a little sparkle and shine in your creations, I highly recommend using a biodegradeable glitter. There are lots of fantastic options available.

Directions

In a large mixing bowl, add the baking soda, citric acid, kaolin clay and cream of tartar. This is our dry ingredient mix. Mix it together completely.

In a microwave safe cup add your coconut oil and kokum butter and melt it in the microwave until it is just liquid.

Add the polysorbate 80 and the essential oils to the coconut oil. Mix.

Now add the liquid mixture to the dry mix in the large bowl. Add the biodegradable glitter. Start mixing it all together. Use your hands (you may wish to wear disposable gloves) and really mix it together well, ensuring there are no lumps. It is perfect when it forms lumps when you squish it, like wet sand.

Separate the mixture evenly into the 5 smaller bowls. Mix in 1 in teaspoon of the purple mica in the first bowl, the blue in the second, the yellow in the third, the pink in fourth and green in the last bowl. If you desire darker color, add additional mica.

Next you can proceed one of two ways to make your unicorn galaxy bath bombs.

1 – You can loosely mix the colours first in a bowls. Basically add about 1 tablespoon of each of the colors. Then using your fingertips, very slightly mix the colors together. If you mix too much or too hard, it will muddy the colors. Then use this mix to pack the bath bombs.

2 – Or you can take pinches of the different colours and add them to your bath bomb molds until they are filled. The choice is yours and will give slightly different effects. You can even try both approaches and see which one turns out the best!

To pack the molds, loosely heap the mixture into each half of the bath bomb mold. Press the two halves together and grind until the edges meet up. Tap the ends of the mold. You will feel it move inside the mold. Then lift off one side of the mold carefully to reveal your bath bomb.

Set the bath bombs on a mini-muffin tray. This helps prevent them rolling and moving about while they are setting. Place the bath bombs in a warm, dry place and let them harden and set up for at least 24 hours. I usually wait 48 hours just to be sure.

To use your bath bombs simply add to a warm bath and enjoy the fragrant fizz!

A Bath Bomb Science Lesson for Kids

The thing we love about bath bombs is that the science appeals to kids of all ages. They love it when science erupts!

In bath bombs the fizzy eruption is caused by a reaction between acids and bases. Our acids in this recipe are citric acid and cream of tartar. Our base is sodium bicarbonate (also known as baking soda). In their dry state they don’t react, but add warm water and you will get a fun reaction. Want a bigger reaction? Use warmer water! We discovered this connection between water temperature and the intensity of the reaction in our bath bomb science fair project.

Another really cool bit of science is around solubility. Everyone knows oil and water don’t mix. Oil is not soluble. But if we don’t do something about this, all the oils, fragrances and colours in our bath bombs will float in a scummy layer on top of the water, sticking to everything. So what do we use? An emulsifier called polysorbate 80. You can see it in action when we made our Moon Dough recipe.

Have fun making bath bombs with your kids!