There seems to be very little information about how much emulsifier to use in an oil-in-water emulsion. The concentration of emulsifier in any formula would have to have some direct relationship to the amount of Lipids that need to be emulsified in the formula. For example if you're Lipid phase is 20% of the total formula, then would you use 1%, 2%, 3% or 4% to have an emulsion that is both stable and cosmetically gentle but effective. I only found one laboratory/manufacture of cosmetic supply ingredients that mentioned an "optimal" amount would be 10 percent matching the Lipids phase - for example if you have 30% lipid phase, then they recommend using 3% emulsifier(s), which should be a blend of high-HLB and low-HLB emulsifiers. I understand that if you increase the amount of emulsifiers higher than is necessary you are decreasing the molecular size, but also potentially creating something that could irritate the skin because it could be too "soapy" or have cleansing qualities.
Anyone have information and/or experience about a good protocol for matching the concentration of emulsifier to the percentage of lipid phase in the formula.
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