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Experiences with preserving w/o’s?
Hey all,
Due to customers demand we are exchanging the parabens out of out formulas.
Some of them were pretty easy by using euxyl pe 9010 that is phenoxyethanol and ethylhexyl glycerin. But when it comes to w/o emulsions i need to recognice a breaking of the emulsion after a while. -even at RT.
I dont find so much about it in the Internet, but could imaging that the structure of the phenoxyethanol causes this breaking.
Has anyone experiences preserving w/o’s?
Thank you! -
13 Replies
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I understand what your problem is Lara but unfortunately can’t help with w/o. Sorry.
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first things first: what’s in your oil phase, how much water is there, which emulsifiers are you using, and what temperature are you forming your emulsion at?
also, when you say it’s breaking, is it bleeding, or is it separating into two layers? -
For example i have a formula like this:
Phase A:
Polyglyceryl-3 diisostearate 1.0
polyglyceryl-2 dipolyhydroxy stearate 4.0
Ceresin 1.0
Mineral oil, low visc. 8.0
Isopropyl palmitate 7.0
Dicapryl carbonate 3.0Phase B:
Aqua, demin. 67.7
Glycein 6.5
Magnesium sulfate 1.0Phase C
Mixtures of parabens (OLD)
Phenoxyethanol, Ethylhexylglycerin(NEW) 0.5Fragrance 0.3%
The phases are combined at 80°C
With braking I mean that the surfaces are bleeding.Additionally I have to say, that we dont do microbiological test, we just evaluate visually and olfactively the single bases and we also compare the new one against the old one.
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as I see it, the root cause of your problem is that phenoxyethanol is soluble in water at 80°C, and hardly soluble at all at room temperature
so when your emulsion is formed, it initially partitions into to the water phase, but as it cools down some of it migrates into the oil
when I’ve used Euxyl PE9010 in W/O products, I’ve always added it after the emulsion has been formed, for that very reason, and I’ve not had a problem with it yet
(incidentally, 80°C seems excessively high for this type of product; a good way to reduce bleeding would be to combine phase A and B at a temperature that’s above the drop point of your oil phase, but otherwise as low as possible, since the same phenomenon affecting the phenoxyethanol can affect your emulsifiers too)
hope this helps!
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Surely this is not a W/O emulsion but an O/W emulsion with water at 68%?
Insufficient emulsifiers. -
Thank you for your very fast answer.
Sorry, that i was not clear enough! The preservative is added, when the emulsion is cooled down to RT again.
As the formula was developed a while ago before i started i am not so into the ideas behind the mi.
But i think i should really try to use a lower temperature to combine the phases to see if they are stable longer than three months RF, RT, 40°C.Today i had another thought…In some literature i found, that glycerin/glycols and/or magnesium sulfate can be used to stabilize the w/o, but if added at a too high dosage of both, they can react also to make the formula unstable.
As the new preservative now also containes a glycerine i thought that may be this border is reached….
So I will also go down with the total glycerine amount in the formula to see what will happen.
Thank you for your support! -
Hey Belassi
The texture of the formula is w/o like. But unfortunately i have defenetively no w/o - expierience wether theoretically nor practically. Additionally i am left alone at work with this problem.
is there another way to detect if it is an w/o or an o/w with an easy quick test.7
Some of the contained ingredients i would not put in any formula that i develope from the start. But i just have to look that we are on the safe side with the use of the surfactant.
Sorry, that i am so a newbie
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Polyglyceryl esters are typically low HLB emulsifiers so I am almost positive this is a W/O emulsion. I wouldn’t be concerned about the water level as I have made stable w/o emulsions with as high as 70% water. The key is the electrolyte (magnesium sulfate) as that is what keeps the emulsifiers at the interface.
An easy test you can do to check what kind of emulsion you have is to take a drop or two of the product and put it into a small amount of water and mix it. If it the droplet “dissolves” or you start to see it sort of disintegrate into the water right away, then your continuous phase is most likely water (thus, an o/w emulsion). If it doesn’t really dissolve and the droplet stays pretty well intact with mixing, then the continuous phase is not water soluble (thus a w/o emulsion).You can also try measuring the pH. If you see a lot of drift or if your meter doesn’t stabilize, you’ve got a w/o emulsion (or a broken pH meter). -
Sorry, i am just wondering if the recent comments have been deleted?
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Good morning all,
Yesterday i was able to Set up the Test serie. Three months of waiting and we will have the results.
As there was some time left i set up an additionally test where i acded 1% of sorbitan stearate to the oil Phase to see what happens. When cooles down i had to recognice the emulsion was way thinner Than the starting formula. Does this mean my formula is overloaded with emulsifiers?
Really im making the first experiences with formulating w/os
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in my view you’ve got a good formula there, but you’ve just got to find the best way of making itI can’t stress enough that processing is a HUGE contributing factor for W/O emulsion stability - for best results, form the emulsion at as low a temperature as you can get away with, use a good shear mixer with a fine screen on the stator head, and be sure to make your batches consistently every timepersonally, if I were to add anything it’d be hydrogenated castor oil (Cutina HR from BASF, also available from Vertellus and a few others) - it’s a rheology modifier which helps to stabilise it at higher temperaturesin my experience, 1% is usually sufficient
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Thickness in a W/O emulsion has a huge dependence on both the number and the size of the internal phase droplets, with the viscosity of the external (oil) phase coming in a close third.
The viscosity of a W/O emulsion that has many tiny water droplets is typically lower than the viscosity of a W/O emulsion that has fewer, larger droplets (at least until you get enough water into the formula that the tiny droplets are packed tightly together)So, it’s reasonable to think that if adding 1% of an emulsifier dropped your viscosity, the most likely scenario is that your water droplets were made smaller.But this also means that what Bill pointed out is critically important. Processing variations can easily overwhelm formula changes in W/O emulsions, so to be able to evaluate formula changes at all, you need to keep your process precisely the same each time. -
Hey all,
Sorry i wasnt Online a long time.
10days results are available now. Rf, rt and 50℃.
All samples shower to be unstable at 50℃ after 10d. Fortunately the old STD is the worst when it comes to separation an Top of the formula. All the samples showed to build Kind of liquid filled craters on the surface. Besides the sample containing sorbitan stearate.-here a complete Phase separation was visible.
For all the reworks i combined the phases at 70℃. Seems to be a good point to start. Im Looking forward for one month 40℃.
Thanks for the advise about cutina hr. I will try this when the Test failes.
Thanks for all your help
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