To make them you will need:
• 1 cup of cornstarch
• 1 cup of citric acid
• 2 cups of baking soda
• 1/2 cup of Epsom salt
• 1/2 cup of sea salt
• 2 tsp. of distilled water
• 1/2 tsp. of borax
• 1-2 tsp. of essential oil or fragrance oil
• 2 tbsp of light oil
You may also want to add a few drops of a soap safe dye colorant
Bath Bomb Supplies
You will also need:
• a big mixing bowl
• a whisk or mixer with a whisk attachment
• several measuring cups and spoons
• something to mix the wet phase in
• a sieve or sifter
• a spoon or two
• a spray bottle with distilled water in it
• a mold for the bath bombs
You will need a cookie sheet with paper towels for the bombs to dry on.
Mix the Bath Bomb Dry Ingredients
Sift all of your dry ingredients into your mixing bowl and stir them well to make sure they are blended well and no clumps remain.
Add the Bath Bomb Wet Ingredients
For the wet phase, put the water into your squirt bottle and add the borax. Be sure to add the borax before you add the other ingredients. If you are using a liquid colorant, add your colorant to the water/borax mixture. Add the fragrance or essential oil and your light vegetable oil. Shake well so that the whole mixture becomes emulsified.
With your whisk in hand, squirt a few drops of the oil/water/borax mixture into the center of the dry ingredients. It is going to immediately start to fizz. Start mixing right away with the whisk. This stops the fizzing by incorporating the liquid into the rest of the dry ingredients.
Test the Bath Bomb Consistency
It is now time to test the mixture. The desired consistency is kind of like wet sand- just barely wet enough to stick together. Pick up a half handful of the mix and squeeze it together. Does it clump into a ball? Or more important, does it remain clumped? If so, great, you can begin molding. If they are still too dry, use your spray bottle of water to add just a bit more water.
Mold the Bath Bombs
The most popular mold seems to be ball-shape. I am using a clear, plastic, two-piece Christmas ornament here. Overfill each half with the mixture, and press them together firmly. You want the edges of the mold to just barely come together while getting a really good pack on the mixture inside. Let the molded ball sit for a minute or two. Then tap the side of the ball firmly with a tablespoon. The side of the mold should gently lift off.
Repeat on the other side. Even with your mixture perfectly balanced, you will occasionally get a ball that will crumble or be flowed or broken. No problem. Just crushes it up, put it back into the bowl and remold it.
Dry the Bath Bombs
Gently lay the tablets or balls onto a paper towel lined cookie sheet or plate. At this point, they will still be a little bit soft, but after drying overnight they will be really hard and ready for the bathtub!