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Why did my shampoo become hazy and less foaming as I lower the pH?
I am using the below formulation for an anti-dandruff shampoo. Shampoo was clear before pH adjustment.
Initial pH - 8.62, clear
1st adjustment - 8.18, clear
2nd adjustment - 7,73, hazy
q.s Water
8% Potassium Cocoyl Glycinate
(and) Potassium Cocoate (and) Water8% Sodium Lauroamphoacetate
10% Cocamidopropyl Betaine
1.5% Coco diethanolamide
1.5% Polyquaternium 7
3% PEG-120 Methyl Glucose Dioleate
0.5% Saccharide Isomerate (and) Aqua (and) Citric Acid (and) Sodium Citrate
0.5% PIROCTONE OLAMINE
2% Panthenol
1% Phenoxyethanol, Ethylhexylglycerin
1% Polysorbate 20
Any idea what is the cause for the hazy?
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3 Replies
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You are using Potassium Cocoate which is a true soap (carboxylate). These kinds of surfactants need to remain at alkaline pH (close to 9-10) otherwise you protonate the carboxylic acid group and your material can become insoluble. So my guess is the pH was brought down too far and you lost the solubility (and performance) of that surfactant
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@EricT Those potassium soaps start losing their solubility the lower the pH difference. That is your haze factor. I’ll also mention piroctone doesn’t care for lower pH either, even as it is mainly insoluble to begin with. Switch those out with a standard anionic such as SLES or SLS (I know: sulfates - EEEK!) and you will feel better. Better yet use ALS and drop pH < 7.5. ALS is a better hydrotrope for piroctone olamine.
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I actually trial and error with the formulation and the hazy issue was resolve by removing PQ 7. Replace PQ 7 with water and the final shampoo was clear and without a hint of hazy at pH below 7.5.
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