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Guidance in w/o emulsion
💕Who has good experience with w /o emulsion.💞
💡I want to know more details about it. I read many references for making that type however some details aren’t precise :
1) Many emulsfiers can be used. According to your experience what is(are) the best emulsfier(s) for w/o
2)Many references speak about using magnesium sulfate, sodium chloride so I want to know espacially how to fix the optimal level of use then wich better work with magnesium sulphate alone, sodium chloride alone or combination?
3) What are the best ingredients that help more the stability : wax, ester, polymer…?
4) Process, all seen references says that process is soo important for the stability of w/o emulsion so who can propose good process for that type of emulsion?
5) Which are the best additions for better sensory feeling for w/o emulsion?
6) What is the optimal ratio proposed (w, o) to get the best results (stability, sensory feeling)
7) For w/o many references say that after emulsion we can not talk about pH of product because the external phase is oil and I find that soo logic however I find famous suppliers that make w/o then they give the pH of product how to explain that?
Looking forward to hearing from you even information that doesn’t answer my question
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7 Replies
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“I read many references for making that type however some details aren’t precise”- they can’t be as it depends on the overall formula.
1) Not a fan of w/o- forced to make one for a project and it proved unstable (split in month 2), so I’ll refrain to highlight any emulsifier as I’m not sure what went wrong. Regardless, I’ve spent a lot of time gathering data on w/o emulsions before starting my experiments- yup, the final one which split after 2 months was experiment no 12.
2) My understanding is that magnesium sulfate is supposed work be better. Electrolytes help partition more emulsifier to the interface and reduce inter-facial tension, leading to greater stability. Divalent electrolytes, such as magnesium sulfate, are typically more effective in this role than monovalent electrolytes like sodium chloride. Some people argue that a mixture of both helps better with stability- no idea if that’s the case.
3) A wax can definitely help with stability. An ester can help only with the skin-feel, and personally, I doubt that a polymer can help with stability in w/o.
4) This seems a good article on that. Emphasis on the word “slowly”.
https://nyscc.org/blog/formulating-effective-and-stable-without-emulsions/
5) I think the most important is to get the oil phase right (“cascading emollients” concept can help), although EVERY ingredient used can impact both, the stability and the sensory profile.
6) There is no such thing as there are too many variables, including the oils used (mineral, plant, silicone). A good place to start is 30 to 70 (w to o) and then adjust based on your experiments. Matching the polarity of the emulsifier with the oil phase can improve stability, which in turn will affect the w/o ratio (one could increase the water %).
7) Considering one has to measure and adjust the pH of the water phase, I assume they use that result.
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Thanks alot @Aniela very informative just can you explain more cascading emollients or any references you recommend 😊
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You’ll find a short explanation here, under “What are esters”
https://cosmetics.iql-nog.com/content/8-basic-concepts
and a more detailed one here, in @Graillotion‘s comments
https://chemistscorner.com/cosmeticsciencetalk/discussion/emollients-2/
Also feel free to search the www for more😉
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Thanks a lot, i’am always searching just to find better, faster reference.
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Hello @Fekher you ask many questions regarding w/o (invert) emulsifications, so I’ll just answer some basics. Nearly everything about o/w emulsions is turned 180 degrees around for these systems. The best emulsifiers to use are the alkyl ether silanes (see Dowsil, ShinEtsu, Siltech products) and very little is needed (1.0 - 3.0%), where usually more emulsifier will enhance o/w formulae. Magnesium Sulfate will destabilize o/w but stabilizes w/o by increasing the osmotic pressure and NaCl works nearly as well. A high internal phase will fail in o/w but enhances stability in w/o (see HIP w/o emulsions). Add the internal phase (water) very slowly with mild agitation - the opposite of higher shear needed for o/w system. Do not add polymers to the water phase: large molecules do not like to be made smaller inside these micelles. When it comes to w/o, w/o/w or w/Si emulsion chemistry, this is Upside Down World.
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I meant lipo polymer because hydro ones don’t help a lot in w/o.
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