Preservative queries for a hair conditioner.
(1) I am considering using Optiphen ND. Is anyone aware of issues with this preservative if the recipe includes Cetrimonium Chloride (cationic conditioner) and Hydrolyzed Soy Protein? I remember reading somewhere that these may inactivate the Optiphen ND.
(2) As an alternative I am considering using Phenoxyethanol & Benzyl Alcohol. Any opinions/advice on these?
(3) Another option is Potassium sorbate & Phenoxyethanol. Again, any opinions?