Active Time
30-45 minutes
Total Project Time
1 to 2 days
Key Concepts
bath bombs, chemical reactions, acids, bases, carbon dioxide
Three blue and three pink domes sit on a plate


Have you ever had a refreshing bath using a bath bomb? It can be quite the relaxing experience, especially if your bath bomb has a nice fragrance or includes some bath salts. Have you ever wondered what causes a bath bomb to become so fizzy when it touches the water in the bathtub? It is due to a chemical reaction taking place between different ingredients within the bath bomb. In this activity, you will get to make your own homemade bath bombs and explore how changing the amounts of the different ingredients affects how fizzy the bath bombs end up being when you toss them in the bath. You can use your perfected method to create some super satisfying bath bombs!


Teisha Rowland, PhD, Science Buddies
Svenja Lohner, PhD, Science Buddies
This activity is not recommended for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.


  • Bath Bomb Science Kit, available from our partner Home Science Tools. Includes:

    • Spherical bath bomb molds (6 spheres)
    • Cornstarch (1 lb)
    • Baking soda (1 lb)
    • Epsom salt (1 lb)
    • Citric acid (8 ounces)
    • Food colors (red, blue, green, yellow)
    • Fragrance (1/2 oz. raspberry, 1/2 oz. vanilla)
    • Waterproof thermometer
  • You will also need to gather these items:
  • Large bowls (4)
  • Masking tape or painter's tape
  • Pen or permanent marker
  • Metric measuring cup
  • Water
  • Vegetable oil
  • Medicine dropper
  • Measuring spoons
  • Forks and spoons for mixing
  • Stopwatch or timer
  • Optional: Helper to help you time the reaction times.
  • Optional, but recommended: Oven
    Note: If you live in a very humid environment, use the oven to dry the bath bombs after making them to get satisfying results. Note that you can use the plastic molds in the oven at 170°F.
  • Disclaimer: Science Buddies participates in affiliate programs with Home Science Tools,, Carolina Biological, and Jameco Electronics. Proceeds from the affiliate programs help support Science Buddies, a 501(c)(3) public charity, and keep our resources free for everyone. Our top priority is student learning. If you have any comments (positive or negative) related to purchases you've made for science projects from recommendations on our site, please let us know. Write to us at


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Active Time
30-45 minutes
Total Project Time
1 to 2 days
Key Concepts
bath bombs, chemical reactions, acids, bases, carbon dioxide
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