Everyone loves baths. A bath bomb—a delightful chunk of good-smelling stuff that explodes into colorful fizz in your bathtub—is therefore an awesome gift on any occasion. But they can get a little pricy. If you buy ingredients in bulk and learn how make bath bombs on your own, you can get a lot more bang for your buck. Plus, you can customize color, scent, and shape to perfectly suit the holiday—or the lucky recipient. And no one will know if you save a couple dozen for yourself. Find how to make a bath bomb for yourself here!
This bath bomb recipe makes about 12 orbs of colorful fun, but the exact count will depend on the size of the silicone bath bomb molds you use.
Homemade bath bomb stats:
- Time: 10 minutes of work, several hours of drying time
- Cost: About $2 per bomb if you make a dozen and more if you add biodegradable glitter—but prices drop if you make a big batch
- Difficulty: Easy
Bath bomb ingredients
- 8 oz baking soda
- 4 oz Epsom salt
- 4 oz corn starch
- 4 oz citric acid
- Large bowl
- Biodegradable glitter or dried flower petals (optional)
- 2.5 tablespoons coconut oil (or any other veggie oil)
- About 1 tablespoon water
- About 2 teaspoons essential oil (for scent)
- 4-6 drops of food coloring
- Small jar or bowl
- 12-18 silicone bath bomb molds or candy/cake molds
Sign up for PopSci’s newsletter and receive the latest science and tech updates to your inbox.
Bath bomb recipe
- First, mix the dry bath bomb ingredients (baking soda, Epsom salt, corn starch, and citric acid) together in a large bowl. Use the whisk to make sure the mixture is clump-free. Baking soda, also known as sodium bicarbonate, is the key to making your DIY bath bombs explode: When the high pH powder reacts with a low pH acid, it produces carbon dioxide bubbles. Remember those baking soda and vinegar volcanoes you made in elementary school? Citric acid takes the place of vinegar in this chemical equation, but it doesn’t react with sodium bicarbonate until it gets wet. If you want, you can add visual decorations like biodegradable glitter into the mix. Just don’t use regular-old craft glitter, because it’s no good for our friends in the ocean.
- Now mix up the wet bath bomb ingredients (oil, water, essential oil, and food coloring). The easiest way to get this party started is to put them in a jar and shake them up. This is the step where you need to make some important decisions about scent. You can tweak quantity to suit your taste, but you should use about two teaspoons total of essential oil or perfume. Try cinnamon, cocoa, peppermint, or coffee scents for the winter holidays (or a combination of all four to make mocha-licious bath bombs). Or go with something classic, like a spa-like eucalyptus and lavender mix or a straight-up sugary hit of vanilla extract. The possibilities are truly endless. It’s also time to make decisions about color. We recommend sticking to a single hue to avoid accidentally muddying the bath waters. Stick to something like 4-6 drops of food coloring total, but feel free to mix up different pigments.
- Slowly add the liquid to the dry mixture. Really slowly. Like a teaspoon at a time. You don’t want your DIY bath bombs to explode prematurely. Whisk as you go, and slow down if things start to look fizzy. You should end up with a mixture that just barely clumps together, like damp sand.
- Stuff that stuff into your silicone bath bomb molds, ASAP. You don’t want the mix to dry out while it’s still in the bowl, which is why you should make sure you have enough molds to make a dozen or more bath bombs at once. Press the mixture down firmly into your molds of choice.
- Let your homemade bath bombs dry. If your mold has a lot of details in it, you might just want to give them a whole day to be safe. Then pop them out.
- Throw one into the tub and enjoy the explosive fruits of your labor. Bag the rest of your DIY bath bombs in cellophane and make your friends and family love you forever.