Hi fellow formulators
I'm having trouble choosing the right surfactants for a gentle AHA cleanser, pH=4.5, sulfate free.
Below is what I have tested so far;
1- 10% Sodium Cocoyl Glutamate (Plantapon ACG HC) in water
- Reducing the pH to 5.0 using Lactic Acid, completely opaque, viscosity broke, after 5 minutes sitting without mixing, turned to an opaque gel.
2- 10% Disodium Cocoamphodiacetate (Dehyton DC-AS) in water
- Reducing the pH to 5.8 using Lactic Acid, completely opaque
3- 10% Sodium Lauramphodiacetate in water
- Reducing the pH to 4.5 using Lactic Acid, clear no sediment
4- 10% Coco Glucoside or 10% Caprylyl/Capryl Glucoside in water
- Reducing the pH to 4 using Lactic Acid, they both stay clear with no sediments.
My questions are:
- What is the best Anionic surfactant (sulfate free) option for pH around 4.5?
- Why Cocoamphodiacetate is unstable at low pH while Lauramphodiacetate is stable?
- Between Coco Glucoside and Caprylyl/Capryl Glucoside, which one has a better foam and milder?
- Is there a source to compare surfactants mildness, foam and pH stability?
Thanks for reading this long post and hope to hear your thoughts.