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Sodium chloride in biphasic products
Hi!
I’ve been trying to develop some biphasic formulations lately (cleansers, ‘oils’, seruns) and I noticed that a lot of products being sold in the market have sodium chloride in the composition. Does anyone knows what is the function of the sodium chloride in these type of formulations? I think it’s to turn the water phase more polar and therefore turn the separation more clear, but maybe I’m wrong.
Also, does anyone knows how much of sodium chloride is normally added in these formulations. I’ve been thinking about 0.3-1%.
Thanks in advance, my fellow chemists 🙂
Kind regards.
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9 Replies
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That would be a good guess, especially if those biphasics are lipid/aqueous. NaCl will usually destabilize standard colloidal systems. Honestly, I don’t quite “get” these, and they pop up as gimmicks from time to time.
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Thank you, Matt!
This is exactly what I thought; it is used to destabilize the system. I’m using it now at 0.4%.
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it’s used to accelerate phase separation; benzyl alcohol is also used for this purpose, and to ensure clean separation of the phases (it helps dissipate entrained air in the oil phase, not sure how or why)
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Thank you, Bill!
Didn’t know that about Benzyl Alcohol. Interesting!
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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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I think it depends… In the case of biphasic makeup removers, for example, I think the oil phase can facilitate the removal of waterproof makeup, and the water phase can facilitate the removal of water soluble residues and turn the product less heavy, as well. But in other cases is more of a marketing thing. In my case, I’m developing a hair mist and it being biphasic is more of a marketing thing.
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“for example, I think the oil phase can facilitate the removal of waterproof makeup, and the water phase can facilitate the removal of water soluble residues and turn the product less heavy” And why the normal emulsion cannot do the same?
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Depends on the system and the amount but I do believe it helps speed the separation. Adding salt will increase the aqueous phases’ density as well. Also if the system contains some surfactant, salt can be added to tweak the HLD=0.
https://www.stevenabbott.co.uk/practical-surfactants/hld.php
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Interesting! Thank you.
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