Bubble Bath Struggle

I can make bath bomb (or bath fizzy) very easily and it works perfectly in the tub every single time.  But I really want some pizzazz to this, up a level to something more luxurious, or should I say fun?!   What kind of a bath is it without some bubble?!  However, I think I struggled to find the perfect combination of ingredients that holds the shape I want it to look.  The easiest rout is to make a dough and roll it into something like a sushi roll then cut it into pieces like what Lush does to their patent product Bubble Bar.  But as restless as I am, I would not be satisfied with an easy way out.  I had a vision of a bubble cube!

Oh~ only if I knew what I got myself into... It all sounded easy, no problem if I use silicone mold.  The problem is the binding agent.  This is a product somewhere in between a bath fizzy and a bubble bar.  It is a bubble bath bomb, meaning it fizzes to help dissolve in water easier but it also produces bubble.  If you have used a bath bomb or bath fizzy before you would know any liquid would set off the fizz action.  How to produce a perfect cube with sharp corners is my hardest challenge.

1st try: I used witch hazel spray, the same method as I bind bath bomb, and as you can see from the photo, a big 2" cube did not hold well.

2nd try: I used a synthetic liquid form of surfactant.  This one went well, but it got wet and started to behave a little like bread dough, hard to unmold.  It took a whole day to harden before I can attempt to take it out in one piece!

3rd try: To speed up the lengthen process, I attempted to freeze and hot air dry the cube.  Well, it all went well until the cubes were out of the freezer defrosting.  The moisture the frozen cubes attracted set off the fizz...  Not bad, just not the smooth texture I visioned.

My conclusion, maybe I should just be patient, stick with the 24 hour drying time and not fight with the nature of this recipe.  I tried my best to formulated to use mostly natural ingredients but in this case I still need to use a synthetic surfactant as a wet binding agent.  Here's the list of my ingredients:

Baking soda

Sodium laurel sulfoacetate

(a natural surfactant derived from coconut & palm oil)

Citric acid

Mango butter

Goat milk powder

Cocamide DEA

(this is the synthetic surfactant)

Polysorbate 80

(to emulsify mango butter to disperse into water)

Fragrance

Colorants

Now, the best thing about this experiment is that I got to be my own guinea pig!  Um... bubble bath...