In a large bowl, mix together 64 oz. of baking soda and 32 oz. of citric acid. To get rid of clumps in the mixture, you can push the powders through a sifter or break them up with your fingers. Citric acid has a tendency to take off nail polish, so wear gloves to protect your manicure. Thoroughly stir the ingredients together.
Add 4 ounces of the cocoa butter to a small heat-safe container and melt in the microwave using 30-60 second bursts. Add 0.8 oz. of polysorbate 80 and 0.9 oz. Pure Honey Fragrance Oil. Use a spoon to fully mix the ingredients together. The polysorbate 80 is there to help disperse the cocoa butter into the tub.
Add the butter mixture to the baking soda and citric acid. Use your hands to thoroughly mix all the ingredients together.
Test the consistency of the bath bomb mixture. The perfect consistency is similar to wet sand that holds its shape when squeezed. If it’s too dry, use one hand to spritz the mixture with witch hazel and one to mix. Continue spritzing until the mixture holds its shape when squeezed.
Fill the two halves of the molds, gently pressing the bath bomb mixture in each so they hold their shape. Mound a little extra mixture in the center of each half of the molds. Wipe away any powder that got in the seams of the mold, match the eyelets of each side up, and press together. To avoid any imperfections on your bath bomb, make sure to direct pressure to the edges of the mold rather than the center. Continue filling up the bath bomb molds until the mixture is gone.
Allow the bath bombs to dry and harden in the molds for 24 hours. Then, carefully remove them from the package. Melt 4 ounces of cocoa butter in a small heat-safe container using 30 second bursts. You don’t want the cocoa butter to get too hot or you’ll need to wait a few hours for it to cool. Add 1 tsp. of cocoa powder and 4 mL of Cocoa Butter Cashmere Fragrance Oil and stir them in completely. We found a good temperature for the cocoa butter is about 75° F. Once it’s a thick yet pourable texture (as shown below) it’s ready to place on the top of the bath bombs. Be ready to work quickly. Just a few degrees can make the butter too thick. If it does become too thick, place the mixture back in the microwave for 3-5 seconds. It doesn’t need a lot of time to warm up.
Use a spoon to plop a dollop of the butter on top of each bath bomb. Sprinkle the pink sea salt immediately on the top before the cocoa butter cools and hardens. Allow the butter to fully cool and harden for several hours. These bath bombs are rather delicate, so they may not be the best option to ship. If giving them as a gift, wrap them very carefully. To use, add them to a very hot tub. The hotter the water, the better. All the cocoa butter in this recipe needs high heat to fully melt.
Recipe by Soap Queen at https://www.soapqueen.com/bath-and-body-tutorials/bath-fizzies/cocoa-butter-bath-bombs/