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Turbidity/Haziness in Shampoo formulation after pH adjustment
Hello, after years of formulating good transparent shampoos with APGs + SCS, I’m now having recurrent problems with a new formulation using APGs + Coco betaine, but without SCS.
The formula is perfectly transparent until the final adjustmant of pH from + 8 to 5.5 with citric acid. The clear formula then becomes hazy/turbid. Any suggestions please?PHASE 1
Sodium Cocoyl glutamate + Sodium cocoyl rice amino acids 20%
Lauryl glucoside 8%
Caprylyl/Capryl glucoside 6%
Coco Betaine 7%
Coco-Glucoside + Glyceryl Oleate 3%
PHASE 2
Aqua 42.64%
Organic Aloe Powder x 200 0.16%
Rice protein (liquid) 3%
Glycerine 4%
Sodium PCA 4%
Dehydroacetic acid + benzyl alcohol 0.8%
Sodium benzoate 0.2%
Potassium sorbate 0.2%
Sodium gluconate 0.2%
Xanthan gum 0.8%
PHASE 3
Citric Acid sol. 50% for pH 5.5
COLD MIX METHOD
Heat Lauryl glucoside until transparent and add to APGs. Slow stir for 15 minutes and add Coco betaine, stir then add Coco-Glucoside + Glyceryl Oleate, stir.
Mix phase 2 ingredients together. Add xanthan gum and homogenise until thickened.
Add phase 2 to phase 1 slowly under constant stirring for 15 mins until well blended.
At this stage the formulation is very good- transparent and sufficiently thick with pH around 8.
Add citric acid (sol. 50% ) slowly under stirring to pH (5.5). The mixture immediately becomes turbid. Any idea Why?
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3 Replies
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My guess is that the Dehydroacetic acid protonates when you add the Citric acid and precipitates out of solution.
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Mmm, thanks Vnnil. That’s one idea I hadn’t considered. I’ll do a trial without and let you know the results!
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Actually, several factors could be the reasons for the Haziness / Turbidity when you add Citric Acid. Your formula looks fine. One of the things I noticed is Almost all of your ingredients have the pH range between 4 and 8 which is close enough to your target pH: 5.5. Only Lauryl Glucoside which has a pH range from 11.5 - 12.5 in most of the blends if you dilute the Raw Material to 10%. You may like to make a small lab batch without it and check whether you will, still, get the Hazy/Turbid appearance. Actually, as long as you have caprylyl/capryl glucoside and cocco glucose + glyceryl oleate in the formula, you may not worry about removing Lauryl Glucoside. Then, you may try using Citric Acid 25% instead of Citric Acid 50% in pH adjustment of the Lab Batch which doesn’t have Lauryl Glucoside. These are just my ideas about your issue. I don’t know whether it will work or not. It didn’t happen with me in the past
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