We are formulating with HEC as a thickener in the formula, and the pH is between 6-7. The initial viscosity was well above 4000 cps, but after 30 and 60 days in the chamber (40C), the viscosity dropped significantly, however the entire shampoo is still clear without any phase separation.
I am wondering if anyone has similar experience with viscosity change of HEC thickened shampoo or other cellulose thickened systems?
Surfactant blend (40% active) 16%
HEC (Tylose 100000) 1%
Cationic conditioner 0.5%
Sodium Benzoate 0.5%
Citric acid q.s. to pH 6-7