Measure 1 cup of baking soda and sift into a large bowl.
Measure 1/2 cup of SLSa and sift into the same bowl as the baking soda
Measure 1/2 cup of citric acid and add it to the bowl with the baking soda and the SLSa.
Using a stand mixer, mix all the ingredients together on low speed for 2 to 3 minutes to make sure they are blended well. As an alternative, you can use a spatula to stir all the ingredients together.
Measure 1/4 cup of Babassu oil and add it to a separate small bowl.
Measure 1/2 tablespoon of polysorbate 80 and add to the babassu oil and stir.
Pour the babassu oil and polysorbate mixture into the bowl that contains your baking soda, SLSa, and citric acid. Use either a stand mixer or a spatula to mix the ingredients together.
Once the desired consistency is reached, separate the bath bomb mix into 4 separate bowls.
Add your first color into one of the 4 bowls that contain the bath bomb mixture and mix in the color by stirring with a spoon or you can use your hands to mix in the color if you are wearing gloves. Repeat this step for each of the remaining bowls until you have 4 different colors.
Start adding each color of the bath bomb mixture into the mold until each half of the mold is filled.
Once each half of the mold is filled and packed tightly with the bath bomb mix, press each half of the mold together and place it in a safe location for the bath bombs to dry for 24 hours.
After 24 hours remove the bath bombs from the molds.