How to Make a Bath Bomb

What are bath bombs?

Bath bombs are small, colorful balls that you drop into a bathtub filled with water. When they touch the water, they fizz, bubble, and often release colors, scents, and sometimes glitter or tiny toys, depending on what you put in it.

What makes bath bombs fizz? 

Bath bombs fizz when a base (baking soda) and an acid (citric acid) react in water. They will not react when they are dry, but when they hit water—the activator—they will fizz and dissolve. They fizz by releasing CO₂ gas (carbon dioxide) which forms the bubbles.

Chemical formula of bath bombs:

3 NaHCO3 ​ (baking soda)+ C6​H8​O7​ (citric acid) → Na3​C6​H5​O7 ​ (sodium citrate)+ 3 CO2​ (gas)+ 3 H2​O (water)

Ingredients for 2 to 3 large bath bombs:

Main ingredients for the reaction:

• Bath bomb mold, see below

• Baking soda: 1 cup

• Citric acid: 1/2 cup

• Cornstarch: 1/4 cup

Other ingredients to enhance and customize:

• Epsom salt: 1/4 to 1/2 cup (optional)

• Almond oil (or another oil): 1.5 to 3 tablespoons

• Food coloring: 5 - 10 drops (optional)

• Biodegradable glitter or dried flowers or herbs: a small pinch (optional)

• Grow capsules: lightly coated in almond oil (optional)

• Scent (essential oils or fragrance oils): 8 - 12 drops, depending on how strong you want it (optional)

More on molds:

If you don't have a bath bomb mold on hand, don't worry! There are many alternate items around the house you can use.

• Silicone muffin cups

• Ice cube trays

• Measuring cups

• Plastic Easter eggs

• Cookie cutters

• Small silicone candy molds

• Muffin tins

• Yogurt cups or small plastic containers

• Silicone chocolate molds

• Your hands; pack them into a ball or any other shape you can manage

Instructions: 

1. Coat the grow-capsule (if you choose to include one) lightly with almond oil and set aside.

   
   

2. In a bowl, thoroughly whisk together the dry ingredients (baking soda, citric acid, Epsom salt, and cornstarch); whisk and remove all lumps.

   
   

3. Put all wet ingredients (food coloring, oil, and scent) in a different cup. (If you want different scents or colors for your bath bombs, take two cups, add 1 to 2 tablespoons of oil, 3-4 drops of food coloring, and 4-6 drops of scent to each cup. Separate your dry mixture in half and put one half in another bowl.)

   
   

4. Add glitter to wet ingredient cup (optional).

   
   

5. Combine wet & dry ingredients by drizzling wet ingredients into mixture, whisking constantly.

   
   

6. Stop when the mixture holds together when squeezed in your hand - it should feel like damp sand, but not wet or sticky. 

   
   

7. Mold the bath bombs: fill each half of your mold with mixture.

   
   

8. Place a grow capsule in the center (if using) - Tip: Don’t over pack around the capsule; it needs a small cavity to expand safely.

   
   

9. Press gently but firmly so the halves stick together.

   
   

10. Do this for your other bath bomb(s)

    
    

11. Leave molds to dry for at least a day.

    
    

12. Once hardened, carefully remove the bath bombs from molds, drop into warm water, and watch it fizz as CO₂ is released.

    
    

13. If using grow capsules, they should expand safely after the fizz settles.

    
    

14. Enjoy!!!