Home Cosmetic Science Talk Formulating GMS vs cetearyl alcohol in emulsion

  • GMS vs cetearyl alcohol in emulsion

    Posted by abdullah on December 14, 2022 at 5:55 am

    For comparison of GMS vs fatty alcohol i made two simple emulsions 


    Petrolatum 5% 
    Glycerin 5% 
    Sodium lauryl sulfate 0.5% 
    GMS 4% 
    Xanthan gum 0.3% 
    Water and others 
    pH 4.8

    B

    Petrolatum 5% 
    Glycerin 5% 
    Sodium lauryl sulfate 0.5% 
    Cetearyl alcohol 4% 
    Xanthan gum 0.3% 
    Water and others 
    pH 4.8

    Both emulsions are stable

    Formula A has higher viscosity, less soaping and costs less than B 

    As fatty alcohol is 2 times more expensive than GMS, i wanted to use just GMS instead of cetearyl alcohol or mixture. Then these questions came to my mind.

    1. What can cetearyl alcohol do than GMS can’t do in simple emulsions like above?

    2. What can cetearyl alcohol do better than GMS in simple emulsion like above 

    3. Why should i not use just GMS instead of both in a formula because GMS cost less, provide more viscosity and less soaping than cetearyl alcohol?

    4. If GMS can do everything cetearyl alcohol do, does it better  and also costs less, why everyone is not using it instead of cetearyl alcohol? 

    ketchito replied 1 year, 2 months ago 6 Members · 14 Replies
  • 14 Replies
  • ggpetrov

    Member
    December 14, 2022 at 8:54 am

    I think they are incomparable. Also it’s very strange that you get a thicker emulsion with the GMS. In my experience GMS tends to give a lower viscosity compared to Cetearyl alcohol. 
    At that percents I guess it’s a pretty heavy and unpleasant emulsion. GMS has a lower hlb value, and tends to lower the whole hlb of the emulsion. This leads to emulsion with a softer touch. Cetearyl alcohol creates a bit “heavier” emulsions, but with more driyer touch.
    In my experience at levels above 2% both GSM and Cetearyl alcohol slows the absorption at all and have waxy and unpleasant touch on the skin.
    Depending of the emulsifier, I usually use both in my emulsions.

  • ketchito

    Member
    December 14, 2022 at 12:38 pm

    As @ggpetrov, you are comparing ingredients with different structure and properties. Fatty alcohol are structuring agents (they don’t have much activity in the interphase), while GMS is a low HLB emulsifier.

    Just out of curiosity, when you mention both emulsions are stable, for how long and in which conditions? I don’t think they are stable during the normal shelf life of a final product (there’s a reason why SLS is used more like a detergent, and that’s its hydrophilic-hydrophobic balance….one anionic surfactant that can be used as emulsifier is Cetyl sulfate, for instante).

  • gordof

    Member
    December 14, 2022 at 12:38 pm

    hi 

    for your questions: 
    1: Cetearyl alcohol builds liquid crystal structures and stabilizes droplets wear GMS is an emulsifier that builds droplets of oil in water. 

    2. The two products both give stability to a product but the way they do it is different wear Cetearyl alcohol stops droplets from building up bigger droplets GMS builds smaller droplets due to more emulsifier present until it is to much emulsifier. 
    If you just use GMS that will not give you the same yield point for the formulation.

    3.The soping effect depends heavily on the emulsifier system Cetearyl alcohol does not push soping in general, it is always depending on the given system. 

    4. it does not do the same thing in a formulation as mentioned. One is an emulsifier the other is a Stability giving liquid crystalin structure builder.

    Yes in some Formulations it can be beneficial to only use GMS because the skin feel can be better or the appearance of the creme is more the way you like it to be. But you can not make it a General rule for all formulations out there in fact most formulations don’t need another co-emulsifier like GMS but they need a Structure builder for long time stability.

  • abdullah

    Member
    December 15, 2022 at 2:28 am

    @ggpetrov yes it is a bit unpleasant.
    Which version of gms were you using? 40% or 90% mono?

    @ketchito these products are stable for less than a month yet at room temperature but i have another sample, same GMS formula but polyglyceryl 4 laurate instead of SLS from 12 months ago and it is stable yet.

    @Gordof thanks a lot

  • ketchito

    Member
    December 15, 2022 at 3:04 am

    @Abdullah Using Polyglyceryl 4 laurate instead of SLS changes the rules of the game (they are nowhere near comparable).

  • abdullah

    Member
    December 15, 2022 at 8:04 am

    ketchito said:

    @Abdullah Using Polyglyceryl 4 laurate instead of SLS changes the rules of the game (they are nowhere near comparable).

    Aren’t they both high hlb surfactants for LGN emulsions?

  • ggpetrov

    Member
    December 15, 2022 at 8:32 am

    If you are talking about a lotion/cream and if you use a high HLB emulsifier, you should use GMS to lower the HLB. It’s hard to explain but the lowering of the HLB makes the emulsions tactile softer and very pleasant. It’s a matter of experiment to get the exact percentage of the GMS, but avoid to use too much. Better start with something small - 1% for example. 

  • abdullah

    Member
    December 15, 2022 at 11:19 am

    ggpetrov said:

    If you are talking about a lotion/cream and if you use a high HLB emulsifier, you should use GMS to lower the HLB. It’s hard to explain but the lowering of the HLB makes the emulsions tactile softer and very pleasant. It’s a matter of experiment to get the exact percentage of the GMS, but avoid to use too much. Better start with something small - 1% for example. 

    That is what i was doing too. 

    As there are blends of emulsifiers that has SLS: GMS and SLS: cetearyl alcohol, i started to make one by myself and see which one is better. 

  • ketchito

    Member
    December 15, 2022 at 11:31 am

    Abdullah said:

    ketchito said:

    @Abdullah Using Polyglyceryl 4 laurate instead of SLS changes the rules of the game (they are nowhere near comparable).

    Aren’t they both high hlb surfactants for LGN emulsions?

    @Abdullah It’s like saying that both a train an a car are vehicles, but well…there are big differences 😁. To start with, SLS is anionic while the other is a polymeric non ionic surfactant. Also, HLB concept is an old concept that doesn’t apply to all type of surfactants and doesn’t explain many phenomena (there are newer models that @Pharma explained very nicely in a previous post). 

    Also, LGN is a very complex concept and you need some equipment to actually confirm you got a crystalline phase, we cannot assume that any emulsifier (even the ones advertised as LGN promoters, which are really not the only ones) with either GMS or a fatty alcohol will produce a lamellar gel network.

  • zetein

    Member
    December 15, 2022 at 11:54 am

    @ketchito Why polyglycerol-4 laurate only needs C12 hydrophobic group, while most other emulsifier are bond with ≥C16 (cetearyl gluside, sodium cetyl phosphate, behentrimonium chloride, ceteareth-20, peg-100 stearate…) (also why peg-100 stearate has to be ethoxylated to 100, uniquely high for a emulsifier!)

  • pharma

    Member
    December 15, 2022 at 8:05 pm

    There’s a good and bief overview on LNGs on UL Prospector.

  • ketchito

    Member
    December 16, 2022 at 11:50 am

    @zetein Since the fatty chain in Polyglycerol-4 laurate is short (mainly C12), it can form o/w emulsions. If on the contrary it was long enough to change its interfacial behavior, then it’d probably form w/o emulsions. Each surfactant molecule has a specific balance in its structure to get specific properties, same as each polyquaternium use a specific monomer to tailor its performance.

  • zetein

    Member
    December 18, 2022 at 10:42 am
    If an emulsion can thicken it self without the use of polymers (saccharides/acrylates), can it be determined that’s LGN working here?
    If not, what would be the names for other kind of self-aggregation that can thicken an emulsion?
  • ketchito

    Member
    December 19, 2022 at 3:57 am

    @zetein A lamellar network is a specific type of micellar arrangement. You have many arrangements in between lamellar and sphetical, some of which also give a viscosity increase (adding polymers increase viscosity even further by entanglement). I’m not saying you won’t have a lamellar gel network when you make a viscous emulsion, but unless you have an x-ray driffractometer, you can’t say for sure which type of arrangement you have in your emulsion.

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