According to this article from Pilot chemicalThe Formulation Basics for Personal Cleansershttps://www.happi.com/contents/view_features/2009-09-02/the-formulation-basics-for-personal-cleansersFor sodium lauryl sulfate and sodium laureth-2 sulfate a good starting ratio is 3:7 on an active surfactant amount basis. This combination of lauryl and laureth sulfate will give a nice, well-balanced lather profile that the consumer expects from a personal cleanser. This ratio is also a good starting point for viscosity response and short flow (non stringy) properties of the final product. Ammonium lauryl/laureth sulfates may be slightly better than their sodium counterparts in amount of foam generated, clarity at lower temperatures and viscosity response in certain formulas but they can release ammonia at higher pH. Regarding rheology, this 3:7 lauryl to laureth sulfate ratio imparts a nice short flow for the system. Higher amounts of lauryl sulfates may cause stringy flow whereas the higher amounts of laureth sulfate will not have optimized creaminess of the lather and may not build maximum viscosity.
I've always wondered if this 3:7 ratio is the reason why some premixes work so well?
Can you lower overall surfactant for milder cleaning, while still keeping this ratio for balanced lather?