Formula separation with Aluminum Chlorohydrate and cooling agent

Question

I would like to ask what ingredient is causing formula separation. The formula is as follows: Aluminum Chlorohydrate 10%, Triethyl citrate 2%, Ethyl Ascorbic acid 2%, Disodium EDTA 0.2%, Butylene Glycol 10%, Menthone Glycerin Acetal 10%, Propanediol : Ethylhexylglycerin 1%, Water qs 100. Is the separation caused by the cooling agent, Menthone Glycerin Acetal (Freeze Me™), being incompatible with the formula? Does using it in a formula with a pH of approximately 4 cause separation? Thank you.

MySkinRecipes Expert · Accepted Answer

Based on the ingredients in your formula and the details about their properties, the most likely cause of the separation is the Menthone Glycerin Acetal (Freeze Me™).

Here's why:

pH Incompatibility: The description for Menthone Glycerin Acetal states that it works best and is stable in formulas with a pH range of 6.5-12. Your formula has a pH of around 4, which is significantly lower than the recommended range.
Solubility Issue: Menthone Glycerin Acetal has very low solubility in water, only up to 0.12%. You are using it at a concentration of 10% in a water-based formula, which exceeds its solubility limit in water.

While Aluminum Chlorohydrate can also be challenging to stabilize in water-based formulas due to its electrolyte nature, the pH and solubility issues with Menthone Glycerin Acetal are the primary reasons for the separation you are observing.

To resolve the separation, you would need to either remove the Menthone Glycerin Acetal from the formula or significantly reformulate the base to be compatible with it, which might not be feasible given the other ingredients like Ethyl Ascorbic Acid and Aluminum Chlorohydrate that require a lower pH range.