Thickening the hand wash with betaine - viscosity issue.
I am trying to thicken a hand wash which contains ALS 30% with betaine. I get the viscosity in spec (7,000 - 9,000 cPs), but the batch thins out significantly when I adjust pH with Sodium Citrate to be 5.0-5.5… it basically crashes… previously the pH range was 4.5 - 5.0 but they added preservatives such as Benzyl Alcohol at 0.5% and Phenoxyethanol at 0.9% apart from potassium sorbate which was in the formula previously. It must be pH related issue as I went very slowly with betaine and did not overshoot.. what to do? Should I set pH to be 4.5-5.0 regardless preservatives efficacy? I needed a lot of sodium citrate to bring it up to be 5.0-5.5 and maybe that is why the batch crashed?