In a large mixing bowl, add the baking soda, citric acid, white kaolin clay and cornstarch.
Whisk dry ingredients together.
Add the coconut oil. This binds all the ingredients together, so you bath bombs don’t crumble when you touch them!
Add the polysorbate 80. This helps the coconut oil disperse more evenly in your bath water, makes the bath bombs bubbly and prevents the mica from sticking to the side of the tub.
Add the rose and lavender essential oils. Mix all ingredients well. You may need to use your hands to break down any lumps and make sure everything is mixed in. The mixture is perfect when it holds together when you press it into your hands and feels like wet sand.
Add 1-2 tablespoons of the dried roses and lavender to the bath bomb mixture. Mix well.
Add the mixture to the silicone or plastic mold.
Press firmly. Fill to the top.
Allow to dry at least 24-36 hours.
To remove, gently pop the bars from the mold. Store in an airtight container until ready to use.