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Foundation (w/si) viscosity issue
Hello All,
I am struggling with a W/Si foundation. My main problem with
it is that if I add pigment to the oil phase and then process the emulsion, the
viscosity is very low (almost water thin). If I add the pigment to the ready
emulsion (it’s smooth and very thick which is what I want) it looks great,
applies great but shows signs of separation the very next day.I process the emulsion as W/O: heat both phases to 70C, add
water by drops under low shear (overhead stirrer) and then homogenize the emulsion
after the temperature drops below 40C. If no pigment is added the emulsion is
thick after I homogenize it. The pigment is TiO2 and Iron Oxides suspended in Octyldodecanol.
Pure pigment concentration is 50%INCI
%
Aqua
38.20%
Phenonip
1.00%
Betaine (trimethylglycine)
2.00%
Glycerin
3.00%
Sodium lactate
1.00%
Sodium PCA
2.00%
Dimethicone 5
10.00%
Isodedecane
4.00%
Hydrogenated Polyisobutene
5.00%
PEG-30 Dipolyhydroxystearate
2.00%
Cetyl PEG / PPG-10/1 Dimethicone
0.70%
Polyglyceryl-3 Triolivate
1.00%
Polyglyceryl-3 Beeswax
1.00%
Sericite Mica
1.00%
Dimethicone / Vinyl Dimethicone Crosspolymer, Silica (powder)
0.60%
Boron nitride
1.00%
Magnesium Stearate
0.50%
Dimethicone / Vinyl Dimethicone Crosspolymer (gel)
3.00%
Trimethylsiloxysilicate (and) cyclopentasyloxane (film former)
3.00%
Custom blend of TiO2 and iron oxides in octyldodecanol
20.00%
Any advice is appreciated.
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35 Replies
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I understand that pigments broke the emulsion. I wonder if that can be fixed by adding some emusifier to the pigment mix..
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Color cosmetics are a pain, speaking from experience!
Boost up levels of existing emulsifiers — your PEGS/PPGs. If you are calculating with HLB make sure to factor in the oil your pigments are dispersed in (it’s easy to forget).
If you have access to other pigment dispersions, I’d give those a try as well - sometimes what the pigments are dispersed in can make or break a fussy emulsion like w/si.
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It is a pain indeed. Unfortunately I only managed to find pigments in octyldodecanol. I didn’t apply HLB system (should it be applied for w/si?). It works fine when I add pigments to the oil phase. It emulsifies and stays together at a room temperature (I didn’t stability test it). But the texture isn’t even close to what I want. I will increase level of emulsifiers, I think it’s always a good idea.
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Did you try pure octyldodecanol to see if it’s this or really the pigments?
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I played with these emulsifiers for a quite a bit before I added pigments. I tested these with several esters including octyldodecanol, no problem at all. It’s clearly about pigments. Oh I forgot to mention the emulsion is thickish with 10% of pigment blend (which translates to 5% pigment and 5% of octyldodecanol), but the coverage is too light.
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Are your pigments coated with anything or are they plain oxides? Coated pigments tend to play nicer with w/si emulsions (emulsions in general, really) in my experience
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how fine is the screen on your homogeniser, and what speed are you running it at?
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Ready dispersion (for makeup) in octyldodecanol. Emulsion without pigment gets viscous after application of high shear. So I guess it’s not easy to get viscous w/si with pigments. Anyone tried?
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Just a guess… Could there be a problem with polarity of my oil phase? I use dimethicone which is non-polar with polar esters. Could that be the reason?
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@Bill_Toge
I think ngarayeva001 uses a stick blender. -
I’m sorry, not to hijack your thread… can anyone explain/elaborate on why cetyl PEG/PPG-10/1 dimethicone is ubiquitous in complexion products?
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Unfortunately I do. It’s possible to find not expensive overhead stirrer but not homogenizer. Also homogenizers are pain to clean and it’s impossible to make 100 g batces. Materials for foundation aren’t cheap.
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@Sponge, the reason I bought this material is that I saw it in every foundation I like. My observation it creates a nice texture but it’s hard to stabilize on its own (w/si made with this alone separates quickly).So, I use three emulsifiers and stabilisers.
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Sponge, that emulsifier from Evonik is perhaps the most commonly used for w/o inverse phase emulsions, always with a co-emulsifier like the polyhydroxystearate. That’s why you see it so often.
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@ngarayeva001 for W/O products you definitely need a homogeniser with a very fine screen, or an extremely high-speed mixer (10,000+ rpm) like an Ultra Turraxalso, it helps to form the emulsion at as low a temperature as practically possible, so any solubility variations during cooldown are kept to a minimumspeaking from experience, the easiest way to clean homogenisers once they’ve been in products like this is to run them in a mixture of very hot water and alkaline detergent; this will shift a lot of the product and reduce the amount of elbow work required to get the rest of it off
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I know that homogenizer is important and I hope to buy it one day. Thank you @Bill_Toge for an idea. Ultra Turex looks small (and I guess allows making small batches) and I found a couple of used models on ebay within $500.
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@ngarayeva001 @chemicalmatt Interesting. Thanks.
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An update: I tried to emulsify pigment blend separately with Polyglyceryl-3 Triolivate and 5% of water and added to the main batch after emulsification (So I basically made one concentrated W/O emulsion with pigments and one W/Si emulsion without pigments). Separated again….
What is really annoying is that the same formula works perfectly with 20% of mineral pigment blend. I am referring to untreated TiO2 and iron oxides, that are not good for a foundation for obvious reasons. My first prototype that I made in late March is still stable..
Regarding the stick blender, although I undertand that it’s not very professional to use it, I don’t think it’s the cause of the separation. I made several W/O and W/Si using it and they don’t separate (at least at the room temperature). Everthing is ok until I add those pigments wetted in octyldodecanol… -
Do I understand you right: You can add other pigments at 20% and it’s fine, you can add octyldodecanol and it’s fine, you add that mysterious blend and it’s not fine, correct?Is it possible that they add something else to those pigments?Did you calculate HLB and HLB requirement (with and without octyldodecanol)?
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@Pharma, the concentration of my pigment blend is 10% (50% pigments, 50% octyldodecanol). The same formula (all other inputs are the same) where I added 10% octyldodecanol to the oilphase and 10% of dry pigments didn’t break. But those dry pigments were for soap making (uncoated and poor quality). I did that as an experiment to see what happens.
I didn’t calculate HLB as I was hoping that since I use a blend of 3 emulsifiers I should be covered.I made another batch on Friday and added pigments in octyldodecanol to the oil phase. Didn’t separate so far, but it’s water thin.
To summarise my problem: I want to achieve a high viscosity foundation. The base has high viscosity without pigments. When pigments added after emulsification, the viscosity stays high but the product separates (within an hour!) when pigments are added to the oil phase, it stays together but it’s water thin.
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ngarayeva001 said:…The same formula (all other inputs are the same) where I added 10% octyldodecanol to the oilphase and 10% of dry pigments didn’t break. …
I didn’t calculate HLB as I was hoping that since I use a blend of 3 emulsifiers I should be covered.
…
To summarise my problem: I want to achieve a high viscosity foundation. The base has high viscosity without pigments. When pigments added after emulsification, the viscosity stays high but the product separates (within an hour!) when pigments are added to the oil phase, it stays together but it’s water thin.Weird… any chance of finding out with what the custom pigments are coated?You actually have 5 emulsifiers in your formula
.Do you have a microscope? You probably don’t have a w/si emulsion but something like a so called liquid crystal aka alpha-gel emulsion which is just on the brink of either breaking or turning into a real water drops in continuous silicon phase emulsion (something like Table 1 on PAGE 4: Lalpha, V2, or H2 turning into I2)… You don’t happen to have a good microscope or a polarised light source (which could either come with the microscope or be self-made using sunglasses).Something you could try: Lower HLB, generally increase surfactants, remove/reduce electrolytes (betaine, glycerin, sodium lactate, and sodium PCA).Gotta go sleepy-sleepy -
Corrigendum: Glycerol is not an electrolyte, don’t remove that one
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@Pharma, you got me thinking… I can only see three emulsifiers in the formula (at least that was my intention): PEG-30 Dipolyhydroxystearate, Cetyl PEG / PPG-10/1 Dimethicone and Polyglyceryl-3 Triolivate, what are the other two? Are you referring to the cera bellina because it’s a PEG?
Regarding electrolytes, the supplier recommends adding electrolytes to stabilise PEG-30 Dipolyhydroxystearate. I don’t like magnesium sulfate, so replaced it with bunch of others. I will try to reduce them. Regarding a microscope, may I ask you to advice what do I need? If something small and not too pricey is suffient for seing droplets shape I will get it. Apologies for my ignorance but I don’t even know what zoom do I need..
By the way thank you very much for your input in my threads as well as in others. It’s great to have a pharmacist who is willing to share their knowledge. You motivated me to dive deeper into a couple of important topics (pH buffers) which clearly made me a little less of a dilettante.
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Yes, cera bellina is an emulsifier and so is magnesium stearate. They may not be used primarily as such but they are (co-)emulsifiers. Magnesium stearate is of special interest because it imparts a negative (inner) surface charge to the inverse micelles.Your supplier is correct . I’m not telling you to reduce them to solve the problem but I’m proposing to completely remove them in a small batch in order to help you finding a solution. In your case, I was a bit short-worded in this regard yesterday evening, sorry! I’m expecting your base emulsion (w/o pigments) to become less viscous and not your liquid endproduct to become viscous again! This experiment would simple help you understand what’s going on with your formula and point towards a worm- or net-like structure which turns into inverse micelles. Then it would be a closer guess assuming that adding your custom blend is destroying your emulsion by changing emulsion type in a certain way. Once you know what causes the issue, finding a cure becomes way more simple.Can’t help you today with the microscope. Have neither tried my old binocular nor the USB microscope to visualise emulsions ;( . It’s on my to do list but… but not today. It needs to be “see-through”, not just a “look on top” (lacking the sciency terms for this
). Maybe @Perry knows which magnification is needed for the everyday life of a cosmetic chemist?Any you’re welcome! Glad I could kick-start your curiosity! -
ngarayeva001 said:@Pharma (…) By the way thank you very much for your input in my threads as well as in others. It’s great to have a pharmacist who is willing to share their knowledge (…)
I second this!
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