Bath Bomb Formulation Advice

It sounds like the issue with your bath bomb formula, where the color is separating with the oil and not dispersing in the water, is likely due to the lack of a solubilizer. While food-grade olive oil can be used, the key is to help the oil (and the oil-dispersed Mica color) mix properly with the water when the bath bomb fizzes.

Here are recommendations to address your questions:

1. Recommended Oil / Solution for Oil Dispersion

The grade of olive oil (food vs. cosmetic) is less critical than ensuring the oil phase disperses in water. To prevent the oil and color from separating and sticking to the tub, you should incorporate a solubilizer into your formula. A common and effective solubilizer for bath bombs is Polysorbate 80.

Polysorbate 80 helps to emulsify the oil and color with the water, allowing them to disperse evenly and reducing the likelihood of a greasy ring or color stain around the tub. You can add Polysorbate 80 to your olive oil and essential oil mixture before combining it with the dry ingredients.

Recommended products include:

• Polysorbate 80 (Tween 80)
• HiPure™ PS80 (Polysorbate 80 Super-Refined)

Add Polysorbate 80 to your oil phase at a recommended usage rate (typically 1-20%, but you may need to experiment to find the right amount for your formula and oil content).

2. Recommended Colorant

Mica powder can be used in bath bombs, but because it is oil-dispersible, it tends to stick to the oils. This is why you are seeing the color separate with the oil. By adding Polysorbate 80 as mentioned above, you will help the Mica disperse properly in the water.

To use Mica effectively and prevent staining:

• Mix your Mica powder thoroughly with the olive oil and Polysorbate 80 mixture before adding this liquid phase to your dry ingredients.
• Ensure the Polysorbate 80 is sufficient to emulsify the amount of oil and Mica used.

Alternatively, you could consider using water-soluble liquid dyes specifically designed for bath bombs, as these will dissolve directly in the water without needing an emulsifier for the color itself (though Polysorbate 80 is still beneficial for dispersing the oils).

By adding Polysorbate 80 to your oil phase and ensuring your Mica is well-dispersed in this mixture before combining with the dry ingredients, you should significantly improve the performance of your bath bombs and prevent the color and oil from separating and staining the tub.