All bath bombs have the same basic recipe, baking soda, citric acid, carrier oil and scent. There are extra additives and benefits of each. I am going to explain to you why each one is used and it's benefits.
Baking soda: aka sodium bicarbonate. Alone, baking soda is harsh on the skin due its high pH level. But in the bath bomb, mixed with the low pH of citric acid, it neutralizes the baking soda.
Citric Acid: this is the ingredient in candies that give it the sour, citrusy flavor. When mixed in a bath bomb with the baking soda, its chemistry causes the fizzing affect by releasing carbon dioxide.
Carrier Oil: this is what helps bring the potent, concentrated essential oil or fragrance oil to your skin. You can use any type of oil from avocado oil to sweet almond oil, but have to keep in mind those that have nut allergies. I use sunflower oil. I get it from a farm in Pitts, GA. It is cold pressed, unrefined and contains no GMO's. Sunflower oil helps dry skin become more supple and oily skin to be acne-free. It also contains antioxidants that help protect your skin from free radicals and adverse affects from the sun. It contains linoleic acid which helps your skin to maintain its natural barriers by supporting the ability to retain moisture.
Cornstarch: this ingredient slows down the fizzle time of the bath bomb. Without it, it would take seconds for it to fizz away in your bath. But with it, it helps it last a few minutes. Cornstarch also is a skin soother. I remember when I was a kid and got chicken pox that my mom would put cornstarch in my water to help soothe my skin.
Cream of Tartar: only a small amount is used and helps the bath bomb to fizz and helps harden
Epsom Salt: I personally do not use this in my bath bombs. Living in the south, we have a pretty humid climate, especially in the summer. While in my testing phase, I noticed that the Epsom salt was drawing moisture in and caused it to react. People use epsom salt in their bath to help soothe achy muscles. It takes a lot of epsom salt to do that. There isn't enough in a bath bomb to benefit from that, so I tell customers that they are welcome to add it in to their soak.
Polysorbate 80: it is a synthetic compound that is derived from polyethoxlated sorbitan and oleic acid. This emulsifier can be found in skin care products, food and cosmetic care products, makeup bases/foundations and shampoos. The function is to help ingredients to dissolve in a solvent, like oil in water. In bath bombs, it helps the carrier oil to mix with the water so you don’t have oil floating on top of the water and also to disperse micas and other colorants into the water to help make the water more vibrant, it also keeps the colorant from sticking to the tub and skin. It helps the essential oil/fragrance oil mix in with the water and oil.
Mica/Water-soluble dyes: these are what gives the water its color. Micas tend to give the water a faint hue, while the dyes create a more vibrant color in the water. All colorants used in a bath bomb have to be approved for cosmetic/skin safe use. Not all micas are approved for the skin. I have used one company since I started for all my micas and dyes because they have a list to show you what colors can be used for bath bombs specifically. Here is a link to provide you more information about it https://www.madmicas.com/pages/what-does-the-fda-regulate
Kaolin clay: this can be found in just about every single product out there from parts in your cars to medications. It’s use in bath bombs is to help harden and help it keep its shape. Kaolin is basically dirt and only a small amount is used in my recipe. If too much is used, it can leave a residue on the skin and in the tub. I was gifted 3 55 lbs bags of it for Christmas so be on the lookout for clay masks in the near future!
I hope this explanation of the ingredients in my bath bombs help you understand what makes them fizzy, foamy and skin loving! Please reach out to me if you have any other questions about my products.