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W/O cream , loses viscosity
Hello everyone, I have a problem, about a formula
Basic formula is
Monomuls 90-O 2%
Lameform TGI 4%
Hydrogenated Microcrystallina cera 4%
Oil phase (including Paraffin oil, Isopropyl myristate & v.low percentage of jojoba oil & tocopheryl Acetate ) 14%
Aluminum stearate 0.25%
Water phase approx. 72% (including MgSO4..07%, Glycerin)
I have this formula in two versions, one, with parabens, and one, with phenoxyethanol & Decylene glycol mix. Both of them seem to lose viscosity (ie. from 100,000cp to 25000cps), which is a huge problem because the packaging material is a jar, of high diameter, and therefore, the bulk is pouring. I recently realized, that shear force, also affects the product. If the product is over-tested (meaning extra stirring, viscosity measurements) it loses viscosity. If after filling you just let it stand there, nothing happens. And last, but not least, the version with the phenoxyethanol & DG, when put in the oven at 50 degrees for 24 h, it regains viscosity and keeps it unless, stirred again… Please do advise..
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7 Replies
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W/O emulsions are usually more stable when the oil makes up the major phase and the water the minor phase.
Is it truly a W/O emulsion? 14% oil (+4% wax) and 72% water do not seem to me to be indicators of high stability.
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sounds like you need to raise oil phase:seems too low for w/o emulsion.
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Also, your emulsifier system is much too weak - the large drop in viscosity is a large clue for this. It looks like most of your viscosity is coming from your wax - the breakdown in viscosity with shear, and the reforming of viscosity with heat are clues for that. You need to reformulate so that most of the viscosity comes from the emulsion structure itself.
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agree with @Bobzchemist - I’d suggest adding a polymeric emulsifier, e.g. PEG-30 dipolyhydroxystearate
also, the relative ratio of the two phases is irrelevant - the nature of the emulsifiers, and that factor alone, determines the nature of the emulsion
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Thank you very much for your replies. The problem is that this is an inherited formula, that nobody really wants to change (it counts more than 10 yrs). I will change it of course to achieve full integrity. Also, by checking out Nivea’s cream, it seems, that they only use Decyl Oleate as an emulsifier, without any other fancy emulsifiers and it looks quite stable as well, with a similar sensorial feeling as our product. Are you familiar, with any oily soluble polymeric thickeners, that could be used in this case? I only can think of Bentone gels and increase in waxes, but the product will be sticky
Dear Bobzchemist, thank you for answering my shear “question”, I really, did not have a clue..why this happens .
I have to play around with the emulsifier system, any suggestions of the “correct” ratio of emulsifiers & oils? I would like to keep it with the same INCI list.
Dear Bill_Toge, my next solution will be ex. Arlacel P135, thank you
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Originally Nivea Creme corresponded to a perfumed version of Oily Cream BP which, in turn was an “official” interpretation of Hydrous Eucerin.
Hydrous Eucerin was composition comprising 50% Wool Alcohols Ointment, 0.5% magnesium sulphate, 1% phenoxyethanol and the remainder being water.
Wool Alcohols Ointment comprises 6% Wool Alcohols, 24% Paraffin Wax, 10% Petrolatum, 60% Mineral Oil. The ratios of the paraffin wax, petrolatum and mineral oil can be varied to suit the climate where the composition is to be used.
The emulsifier in Oily Cream i.e original Nivea was solely wool (lanolin) alcohol and the product stabilised with magnesium sulphate.
They may well use decyl oleate and metal stearates now but the prime emulsifier remains wool alcohols.
Eucerite is the Beiersdorf name for wool alcohol or lanolin alcohol hence Eucerin for the derivates.
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Dear johnb, thank you, it sounds more complicated, than I thought
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