Bath bombs are made with ingredients that are pressed together and solidify as they dry.
In contact with water, a chemical reaction occurs between citric acid and baking soda which gives an effervescent effect.
Some bath bombs have a foaming effect, surfactants like SLSA, SCI and Coco Betaine can be added to increase this effect, we have avoided surfactants and dyes in this recipe to keep it more natural for the little ones.
Fractionated coconut oil is chosen here for its clarity and shelf life. The cocoa butter is here to help hardening the bath bombs.
You can substitute fractionated coconut oil for another light oil (grape seed, sweet almond, avocado, sunflower, etc.) Cocoa butter cand be substituted as well for another butter such as shea or mango butter.
The polysorbate 80 is here to emulsify the oils in water as well as to promote the dispersion of the dyes and thus avoid a colored ring around your bath if you use it. The ratio of polysorbate 80 should be half of the total oils in the recipe. This ratio can vary upwards depending on the oils used.
Cream of tartar is optional, it helps to harden the bombs and gives a 'slowing' effect of the chemical reaction which allows your bath bombs to last longer!
The following recipe will give you 400 g. If you decide to double it, add the oil gradually to avoid adding too much.
Bath bomb recipes often require adjustments based on temperature and relative humidity.
6 g (1.5%) Cocoa Butter
8 g (2%) Polysorbate 80 (substitutes for a light oil)
2 g (0.5%) Fractionated coconut oil
4 g (1%) Fragrance
240 g (60%) Baking soda
120 g (30%) Citric Acid (add to recipe last)
20 g (5%) Cream of tartar
About 2-3 shots of distilled water spray.
Combine baking soda and cream of tartar
Heat the cocoa butter alone and then add the other ingredients of the oily phase.
Add the oily phase to your first mixture and incorporate well. Then add the citric acid.
One spray at a time *, mix everything well to form a ball in your hands. Release there about 30 cm (12 '') above the bowl, if the ball remains firm, the mixture is ready to be molded.
Act relatively quickly, add water as needed if the mixture dries up (a little bit of steaming or two) and be careful not to add too much water to activate the mixture.
* Use a small spray bottle to avoid adding too much water at once. If you notice that it is necessary to add several shots of water spray, adjust your recipe by adding a little oil next time. Relative humidity plays a huge role in the making and drying of bath bombs. A level equal to or less than 30% humidity is ideal.