fareloz
Forum Replies Created
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Sorry for hijacking the question, but what is the purpose of bi-phase systems? Is it just a marketing story or some formulas really work great as bi-phase products?
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Maybe PEG-40 Hydrogenated Castor Oil?
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So you have adjusted pH of acids, added solution of SA with PG and DMI and got higher pH? How this even possible?
SA is known to be stubborn. 20% of PG is definitely not enough.
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Regular soap?
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Most extracts in skincare are glycerin based. When manufacturer add the extract they have to list glycerin too. Since extract is most likely just a marketing ingredient and added on 0.01% amount to have it on the label, I don’t think there is an issue to mix 0.01% of glycerin with 99.9% oils. If it precipitates you won’t even notice. So your product is basically a mix of 2 first ingredients
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Not sure where are you located, but note that Ethoxydiglycol is allowed only up to 2.6% in sprays in Europe https://echa.europa.eu/cosmetics-restricted-substances/-/legislationlist/substance/100.003.563
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This post is obviously just a sophisticated ad of the website attached in the text
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Wee need report user/message feature. The forum has grown and first spam messages already here.
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Sorry, but I can’t believe you have ever prepared this formula. Salicylic Acid 1% will not dissolve in water solution.
Also, Alpha Arbutin requires 5-7 pH value to be stable and Lactic Acid is mostly neutralized in this pH range.
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Nothing wrong, these gel-formers do not tolerate low pH and electrolytes. It’s better to read recommended usage from manufacturer before trying.
I would suggest to use gums instead. For example Xanthan Gum, very reliable thickener. Or Hyaluronic acid (high molecular).
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Is it some kind of two-phase product to shake before use? If so you don’t actually need an emulsifier. Shaking will disperse the oil and create temporary emulsion
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I found the exact INCI:
- Water 50-75%
- Lactic acid 30-50%
- Sodium Lactate 5-10%
- Magnesium Lactate 0.1-1.0%
- Calcium Lactate 0.1-1%
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Does it stay neutralized if the pH is low around 3.5?
pKa is a pH value under which an acid is 50% free and 50% is “neutralized” or better to say is a conjugated base.
pKa of Salicylic Acid is 2.97. So if your solution has pH 2.97 - 50% of added acid is free and 50% is a conjugated base. The higher pH - the less free acid and more conjugated base.
Under pH 3.5 around 23% of added SA is free and 77% is conjugated base (in your case it is Sodium Salicylate).
So “neutralization” is not some point, it is continuous along pH scale. The higher pH - the less free acid and wise versa.
Would that counteract the neutralization from the sodium lactate?
When you mix SA with Sodium Lactate some part of SA replaces Lactic Acid in Sodium Lactate and becomes Sodium Salicylate (+ released Lactic Acid). Sodium Salicylate is highly soluble in water.
Adding more acids will lower pH and release some of SA. But since SA is not soluble in water it will crystalize.
I remember the study you mention, it is here https://www.researchgate.net/publication/44298504_Mixed-solvency_approach_-_Boon_for_solubilization_of_poorly_water-soluble_drugs
Would peg 400 be a better option
I don’t know. I use only PG. You should now worry that much about neutralization. If you can make solution with right pH 3.0-3.5 with Sodium Lactate - that’s fine.
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The reason why Sodium Lactate works is that it “neutralizes” part of Salicylic Acid.
SA + Sodium Lactate -> Sodium Salicylate + Lactic Acid.
Sodium Salicylate is very soluble in water. So you don’t have much of a free acid in your solution.
Same with Sodium Citrate.
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And from here http://www.thecosmeticchemist.com/molecule_of_the_week/guar_hydroxypropyltrimonium_chloride.html:
The dilution and deposition phenomenon occurs when the system is diluted below the critical micelle concentration of the shampoo surfactants, resulting in the formation of the insoluble coacervate
I assume you’ve got insoluble coacervate due to high dilution (too much water?)
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I think Abdullah is right. I just googled the component:
Guar hydroxypropyltrimonium chloride is commonly used as a conditioning agent in shampoo formulations. It forms a coacervate with anionic surfactants from the shampoo formulation upon dilution
So it seems anionic surfactant is causing the problem.
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Your response is such a deja vu to me..
I have a lot of conversations on reddit where people spam me with one-minute googled titles of studies and I spend hour to read them and explain why those studies are irrelevant.
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How can we report this user for ads?
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Sorry, but your friend ether lying to you (because no way SA can be soluble in this solution) or has no clue of what he is doing. It is too many actives to combine in one product and they are not compatible in terms of pH.
BTW what is the pH of your product?
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You can always check the products on the market. For example I googled several two-phase hair sprays and found that they all use combo of some volatile silicone (like Cyclomethicone) + cationic surfactant (like Cetrimonium Chloride).
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Not sure what’s wrong with your ingredients, but Azelaic acid is soluble in pure PG. Here you can see it: https://youtu.be/VssxLD7skQA
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Ah, I see, another clean beauty ad.
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This is very helpful, thank you! I checked SDS on DeLonghi one and found only the pH, not concentration. Maybe I overlooked it:
But they also provide density, maybe I can calculate how much acid based on density.
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FDA is only valid for USA though.