“Frozen” Bath Bombs with color surprise

Hello Everyone!
Here is my updated formula for bath bombs.
This time I have taken inspiration… no wait, I am sure you just cannot guess where I took inspiration from for these bath bombs 😉 it will stay a secret! ahah 😀
I know they look quite boring on the outside, but that’s because there is a surprise in the middle! Keep reading for formula and instructions 😉

I have made quite some experiments on bath bombs lately and I have also studied the formula for “the best bath bomb” from a chemistry perspective, so this is what I believe is the most effective formula at the moment (I am always learning things 😉 so I might tweak this formula again in the future).

Few notes:
– I didn’t add corn starch: it makes the water feel very soft/weird. I tried it in the past and I don’t like it. However, corn starch slows down the reaction so if you want a bath bomb that lasts very long, you might want to add a little.
– I didn’t add oil. There again: oil would have slowed down the reaction, so if you like very slow bath bombs, you can add some oil. However, if you don’t have a powder surfactant (like the SLSA in this recipe) I don’t suggest you to add any oil to your bath bomb, unless you like to clean a greasy tub (the surfactant emulsifies the oil, which means that the bath tub won’t be too greasy eventually).
– Is the SLSA necessary? Well it is not essential for the bath bomb to work, but it is a very good add-on. If you have other powder surfactants, they should work just as well 🙂 The best would have been to mix more powder surfactants together, but since it is just 4% and it doesn’t go directly on the skin I figured I could be a little lazy, formulation-wise.

Now, here is the FORMULA: 

Citric Acid 47%
Sodium Bicarbonate 47% 
Fragrance oil (cosmetic grade) 2% 
SLSA 4% 

Extras: 
Ethyl Alcohol qs 
Glitter (cosmetic grade – you can use micas) qs
Food grade concentrated color (water soluble) qs – I have used a very concentrated liquid water soluble blue color. At the time I didn’t have the powder form but that would have been a better option as some of the citric acid & sodium bicarbonate reacted to the water in the colorant. However, if you do have powder food grade colorants, don’t add it directly to the centre of the bath bomb: mix the colorant with a small amount of citric acid & bicarbonate. This will help the colorant to disperse better and faster in the water (you would risk a big clump of powder colorant to simply sit at the bottom of the bath tub otherwise).

Now to the HOW TO:

1) Measure the citric acid, the sodium bicarbonate, the SLSA. Mix them slowly but very well (breathing the SLSA is NOT GOOD – if you can, do this process open air or place yourself in a position where you don’t get to breathe the powders). Add also the fragrance oil, after the powders are well mixed, and mix again.

2) Add the glitter/mica. I added silver pearl mica (not much) and start spraying the powders with the alcohol while mixing them by hand (use gloves).

3) Keep spraying the alcohol and mixing until the powders are just slighly wet: enough to keep the shape if you squeeze the mixture, but still looking “sandy”.

4) Fill half of the mold with the bath bomb mix. Add a drop of colorant to the centre (or, if you use powder colorant, follow the instructions above)

5) Fully fill the mold and let the bath bombs dry for few hours

6) Take the bath bombs from the mold and place them in a dry room (don’t keep them in the bathroom). If you live in a humid area, it would be a good idea to wrap them in plastic film once they are fully dry.

I had a little bit of leftover bath bomb mix so I made a trial and here is the effect (I tried taking a video but I guess it’s not my thing… 😀 so enjoy the pictures!) 😀 :

Hope you like this formula! 🙂
Have a great day! 😉