What is a bath bomb?
If you don’t know what a bath bomb is, it’s essentially a ball made primarily from sodium bicarbonate (baking soda), which is combined with additional ingredients such as essential oils, fragrances, and other additives.
These balls are then dropped into the tub filled with hot water, releasing an amazing aroma of essential oils, as well as helping to give your skin a spa-like treatment when you soak in the tub afterwards.
Baking soda – the foundation of this recipe. Combined with citric acid it provokes the fizzing action.
Citric acid – the rarer ingredient in this recipe that many don’t have (you’ll have to buy some). The fizzy reaction is like swimming in champagne.
Cornstarch gives us the silky feeling that we all love in bath bombs. In this recipe, we typically use organic cornstarch powder. Arrowroot works as well but does not provide a finished product as silky.
Oil, salt, and liquid – these are all very flexible and you can choose any mix.
Oil – pick a basic olive oil, almond oil, or coconut oil.
Salt – stick to basic salt or add Epsom salt or another favorite salt choice.
Liquid – simple water works, but herbal witch hazel is also useful for extra skin soothing.
Add scents and colors with natural additives, colorants, and essential oils.
How Does it Work?
The “bomb” aspect of a bath bomb is the fizziness. But what’s going on in those spheres that make them so fizzy? Two of the key ingredients to a bath bomb are citric acid and sodium bicarbonate. You might also know sodium bicarbonate by its more common name, baking soda. These two ingredients are what cause the impressive and delightful fizz when the bath bomb enters the water.
When sodium bicarbonate (NaHCO3) comes in contact with water, the sodium (Na) molecules break off from the bicarbonate (HCO3). At the same time, the citric acid is dissolving, with a single hydrogen ion (H+) separating from the rest of the molecule. When the released hydrogen ion from the citric acid encounters the bicarbonate from the baking soda another reaction happens! This time, carbon dioxide (CO2) gas is released as one of the end products. The carbon dioxide forms bubbles in the soap and bath water, and rushes to the surface with a delightful fizz.