I'm working with 100g test batches. I had some trouble dissolving methylparaben (200mg, 0.2%) and propylparaben (100mg, 0.1%) in phenoxyethanol (500mg, 0.5%). The parabens created a slurry in the phenoxyethanol rather than dissolving. Room temp about 20C, so theoretically the parabens should be soluble in water at this level, at least individually.
Adding this to my water phase resulted in the dense slurry hitting the bottom of my beaker and getting smeared around by the magnetic stirrer. Heating up the batch did dissolve the residue, but it later precipitated out after cooling. (The other ingredients in solution were 0.02% Calcium Disodium EDTA and 1.7% Sodium PCA.)
I see that Clariant Phenonip and Euxyl K300 both use 72% phenoxyethanol in their blends. Mine was 62.5%. Do I need more solvent (phenoxyethanol) for the parabens? I'm thinking about making a stock of phenoxyethanol and the parabens. Would being more patient and/or heating it up help dissolve the parabens at these levels, or would heating likely just lead to precipitating out of the phenoxyethanol?
Trying to avoid propylene glycol or ethanol, though I'm aware those can both help solubilize the parabens.
I only have 2oz phenoxyethanol at the moment. I would appreciate some advice on what to try next, so I don't waste my sample. (Aside from just buying Phenonip, which I want to try once it's in stock from Lotion Crafter.)