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NACL AND GLYCERIN IN WATER PHASE
What I cannot understand well, is, in which emulsions/lotions do I have to add in the water phase NACL, and when Ι dont have to.
It has to be a stabization with ions,but I im not so sure about the chemistry that hides behind.
I also would appreciate it if anyone could tell me the purpose of the glycerin in the water phase, apart from humecting.
thank you in advance. -
21 Replies
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Depending on the rest of the formula sodium chloride can act as a thickener. If a buffer is what you need a salt like EDTA is more appropriate.
Glycerin can be used as a solvent.
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It would be very unusual to add sodium chloride to a lotion at all.
Sodium Chloride is used to thicken some surfactant systems (e.g. shampoos, body washes). It can also be used as an exfoliant in anhydrous scrubs.
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Electrolytes like Epsom salts (Mag Sulphate) are often seen in traditional formulations for water in Oil emulsions, but only at pretty low levels.
Most emulsion systems are uncomfortable with high levels of electrolytes -
I’ve always found that NaCl in an emulsion leads to instability so avoided it.
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Are you sure you’re not confusing shampoos with lotions?
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I think I have NOT posed the question correct.I have been working a formula of foundation, W/Si, and one of my suppliers told me to stabilize the emulsion by adding 1% NACL in the aqua phase. This is why I talked for emulsions. I have also seen some formulas in creams/lotions which contain 1% of NACL. I was thinking that it must be an equilibrium between ions, for stabilizing reasons..
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What is NACL?
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Sodium Chloride, NaCl.
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I would never use salt in a lotion. NEVER.
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Is not rare to see comercial formulas with cetyl alcohol and salt, but 0,1% maybe.
I don’t see 1% salt in a formula other than a shampoo. Im curious, what’s on that water phase?.
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The addition of salt for stabilisation seems to be limited to silicon and water emulsions.
This article might be of interest
https://pubs.acs.org/doi/abs/10.1021/ie401490c -
about 0.05%
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Exactly as @DAS said, that is why I asked what was NACL.
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in W/O and W/Si emulsions, salt increases the surface tension of the water phase, allowing it to be emulsified (and stay emulsified) more easily
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Actually salt lowers cmc of SAA which lowers the interfacial Tension:Unfortunately it can also cause a catotrophic phase transition leading to eventual Oswald Ripening followed by coalesce and instability!
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thank you so much @Bill_Toge and @”DRBOB@VERDIENT.BIZ” your information is very helpful.
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salt also brings you good luck if you throw a pinch of it over your left shoulder
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only if you are right-handed:lefties throw it over the right shoulder
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:joy: :joy:
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Thanks again, Bill Toge, for livening this blog with both his science and his wit. To enhance Bill’s insight: salts such as NaCl and Mg sulfate must be added to INVERSE PHASE emulsions (w/Si or w/o) to stabilize these just as Bill says, and also depending on the emulsifier type used. Adding a salt to a standard o/w emulsion is a good way to DESTABILIZE it. I found that 2.0% salt in the water phase of the appropriate w/o or w/Si emulsion does the trick nicely, even though suppliers (Evonik,others) usually state 1.0% or less. Technical tidbit of the day: this is exactly how the trendy HIP emulsions are made. Word.
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