The In's and Out's of using silica as a mattifier and texture enhancer.

GraillotionGraillotion Member
edited July 7 in Formulating
I have been intrigued with silica, but have never used it in formulation.  I bought Aerosil 200 more than a year ago, experimenting with it as a EO fixative, but never made any (noticeable) headway in that area.

As I have been working on some face creams and hand creams, I am needing to enhance some mattifying aspects without diminishing the the texture, in fact hoping to enhance the texture while reducing shine.

Textures are already very good...so texture is the least of my concern, other than doing something that would downgrade the texture.

So I have a sample of Greensil from Greentech on the way....and Aerosil 200 in hand.  I suspect these two products will perform in a similar manner, and only their feedstock differs?  I am looking to reduce gloss on the skin with the consideration of adding silica.

I should say...I already use mattifiers such as arrowroot, Polymethylsilsesquioxane, some crosspolyers etc.  Possibly I am not using them at high enough rates, but I am still looking to reduce skin gloss a tiny bit.

So mainly...I would like to hear from those who have used Silica....The in's and out's of using them...and especially inclusion rates...and techniques....such as time of inclusion, and if the phase of the emulsion matters.  At what minimum inclusion rate does one start to realize an enhanced matte finish?

Also any elaboration on how adding said amount of silica...will change the feel of an emulsified cream would be appreciated.

Is there any negative consumer perception with adding silica to an INCI?

Thank You

Comments

  • I suppose one concern would be....that if these two have fine enough grind...that they don't become an abrasive. :) 

    Does anyone know the comparison of particle size between Aerosil 200 and Greensil?

    One last question...as one of the products I am considering experimenting with this in is cationic... I have had to deal with working around my normal gelling agents.  Silica is sometimes marketed as an oil gelling agent in the 5-10% range.  At the low rates I am considering, 1-2%....will this have any enhancement in creating a gel undertone to the cream?
  • With additional reading... I understand that in order to mattify....the silica needs to be within a certain micron range.  What would be the ideal range with regards to micron and mattifying?
  • PharmaPharma Member, Pharmacist
    The two silica are water-wettable and are quite different on a crystal-structure level (another factor which influences light scattering and therefore mattifying effects) though their chemical composition is identical. Both will show some effect on emulsions, they can even be used to form Pickering emulsions in the absence of any other emulsifier. Bad thing is, they have a negative surface charge and will therefore adhere to the surfaces of the oil droplets killing the positive zeta potential of a cationic emulsion -> simply said, you'll risk losing emulsion stability rather than gaining it.
    Silica with lipophilic coatings (e.g. silica dimethyl silylate) will go into the oil phase and can gel it. They should not interfere with emulsifiers.
    Remember, the optical effects of silicas depend on optical density differences (meaning that the medium they're dispersed in counts) too. Also, water dispersable ones act like arrowroot: Though they do get wet in water, they also get 'wet' in oils and hence bind oils rendering the remaining oil phase on the skin less greasy and less shiny.
  • Bill_TogeBill_Toge Member, Professional Chemist
    Aerosil 200 has a particle size a hell of a lot smaller than Greensil: it's most useful for improving the flowability of powders, and gelling oil-based products, and a lot less useful for mattifying water-based products
    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
  • PattsiPattsi Member
    Aerosil 200 is too small. You need 4.5-7 microns silica. Never had Greensil before so I don't know. might start at 1 and up and down.
    have my eyes on DOWSIL 9701 but can't get my hands on it yet.
  • EVchemEVchem Member
    The aerosil is extremely small and light, highly recommend wearing a well-fitting mask because it will float around if you aren't careful with addition. I've also noticed it can get draggy in higher amounts (>2%), especially if you don't have any silicones/materials to provide slip in the formula.  

    There are a huge variety of starches that may help beyond arrowroot, but I don't know if they have repackers/are accessible for individuals. Maybe you could try  using micas/synthetic micas that are used to create matte looks in makeup?
  • Pharma said:
    ... silica ... Bad thing is, they have a negative surface charge and will therefore adhere to the surfaces of the oil droplets killing the positive zeta potential of a cationic emulsion -> simply said, you'll risk losing emulsion stability rather than gaining it.

    Are you saying for the most part... silica is not used in cationic emulsions?

    Or can low rates along the lines of 1% or less be included without much negative recourse?

    Does the bamboo feedstock have any bearing in this regard?

    If the cationic aspect of the emulsion is not the primary emulsifier, will this create some tolerance?  Aggravation? 
  • suswang8suswang8 Member
    EVchem said:
    The aerosil is extremely small and light, highly recommend wearing a well-fitting mask because it will float around if you aren't careful with addition. I've also noticed it can get draggy in higher amounts (>2%), especially if you don't have any silicones/materials to provide slip in the formula.  

    There are a huge variety of starches that may help beyond arrowroot, but I don't know if they have repackers/are accessible for individuals. Maybe you could try  using micas/synthetic micas that are used to create matte looks in makeup?

    This just in:  One notices that Dr. Hauschka and Weleda are using tapioca starch to achieve this, apparently.
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