Bath Bomb Recipe Instructions 2 cups baking soda 1¼ cup citric acid ¼ cup cornstarch or other starch powder (for buoyancy) Oils, Odors and/or Colorants Combine your powdered ingredients in a bowl and whisk together thoroughly. Add oil, fragrance, and colorant to a separate container or small cup with about ½ ounce of water, then mix to spread colorant evenly. Slowly drizzle the wet ingredients into the powder mixture while stirring until the mixture is evenly distributed without lumps. You will need to use a spray bottle with water to mist the bowl and keep the mixture moist enough to stick together in the mold. Spray 2-3 times every few minutes and keep stirring to prevent ingredients from activating. If it starts to foam, the mixture is too wet. Scoop the mixture into the bomb mold and pack it tightly. Then, manually squeeze the die to form the bath bomb. Repeat until you have the number of bath bombs you want.