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.


Comments

  • I understand that pigments broke the emulsion. I wonder if that can be fixed by adding some emusifier to the pigment mix..
  • gld010gld010 Member

    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.

  • ngarayeva001ngarayeva001 Member
    edited June 10
    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.
  • PharmaPharma Member, Pharmacist
    Did you try pure octyldodecanol to see if it's this or really the pigments?
  • 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.
  • gld010gld010 Member
    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
  • Bill_TogeBill_Toge Member, Professional Chemist
    how fine is the screen on your homogeniser, and what speed are you running it at?
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • 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?
  • 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?
  • DoreenDoreen Member
    @Bill_Toge
    I think ngarayeva001 uses a stick blender.
  • SpongeSponge Member
    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? 
  • 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.
  • @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.
  • chemicalmattchemicalmatt Member, Professional Chemist
    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. 
  • Bill_TogeBill_Toge Member, Professional Chemist
    @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 Turrax
    also, it helps to form the emulsion at as low a temperature as practically possible, so any solubility variations during cooldown are kept to a minimum
    speaking 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
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
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