Confusion with the HLB system

ggpetrovggpetrov Member
edited August 8 in General
Hello. Lately, I am interested to learn how the HLB system works. The reason for that is I want to learn how to combine the different emulsifiers, and also how to define the emulsifiers amount more precisely. I was reading a lot of information about that, also I have found a calculator in Excel which makes the calculations faster, but I am still confused.

Here is my current lipid phase :

* Cetearyl alcohol - 2.5%
* Decyl oleate - 3%
* Octyl palmitate - 2%
* Mineral oil - 2%
* Dimethicone 350 - 2%

The HLB value of this combination is : 11,1

To be honest I am not sure if the all HLB values are correct. For example I have found that the HLB of the Dimethicone can vary in a wide range. But still ...

And now the interesting moment. With this lipid phase I am using two emulsifiers :
Glyceryl Stearate SE - 3%
Methyl Glucose Sesquistearate - 1%
Total HLB - 6

As I understand the HLB values of the emulsifiers and the oil phase are totaly unmatched. But, the emulsion is perfectly fine, stable with a great sensorials. The question is why?

The second combination :
Ceteareth - 25 - 0.5%
GMS - 3%
Total HLB - 5.6 ( This combination is borrowed from the Evonik's Teginacid's formulation giude)

Again, stable emulsion and a great sensorial profile -  easy spreading, fast absorbing, no gloss, no stickiness. Again too far from the desired HLB.

The third combination : (according to HLB)

Ceteareth - 25 - 1.4%
GMS - 3%
Total HLB - 11.1

The emulsion offcourse is a bit more liquid because of the redused amount of the GMS.  But the sensorial is totally different. It feels a bit "heavy" than the previous, also it tends to be more sticky and shiny. It also have a fast absorbtion time, but the overal feeling to the skin isn't the best.

The questions here are two in general :
1. How is it possible to get a stable and fully working emulsions which are totaly out of the HLB system?
2. Does the sensorial properties related with the HLB of the emulsifier system? High HLB gives heavy and more upleasant sensorial, low HLB more pleasant.

The same situation I got with the Lotionpro 165. Used alone it gives light, but unpleasant emulsions which tend to be sticky and glossy.
To be honest I don't understand why's that.



Comments

  • PharmaPharma Member, Pharmacist
    ggpetrov said:
    Hello. Lately, I am interested to learn how the HLB system works Don't. Unless you only work with PEG based emulsifiers. The reason for that is I want to learn how to combine the different emulsifiers, and also how to define the emulsifiers amount more precisely It doesn't help with the amount. I was reading a lot of information about that, also I have found a calculator in Excel which makes the calculations faster, but I am still confused. Obviously. Everyone in his or her right mind should be confused when applying HLB to real life formulations. It's only adding up in half of the cases. I never got along with it, too inaccurate in most cases. Okay as a guideline (the HLB values, not the HLB requirement values).

    Here is my current lipid phase :

    * Cetearyl alcohol - 2.5% Accoring to HLB, this can have a HLB requirement value or an HLB value and be part of the emulsifyer side. According to better systems, fatty alcohols belong to neither.
    * Decyl oleate - 3%
    * Octyl palmitate - 2%
    * Mineral oil - 2% Not a defined molecule, different HLB rey. possible.
    * Dimethicone 350 - 2% Not a defined molecule, different HLB rey. possible.
    Also, HLB req. depends on the type of emulsion and silicones are not exactly following the traditional route of the HLB system.

    The HLB value of this combination is : 11,1

    To be honest I am not sure if the all HLB values are correct Good assumption that they're probably not. For example I have found that the HLB of the Dimethicone can vary in a wide range. But still ...

    And now the interesting moment. With this lipid phase I am using two emulsifiers :
    Glyceryl Stearate SE - 3% SE can mean different types of emulsifiers with different HLB values.
    Methyl Glucose Sesquistearate - 1% Not part of the traditional HLB system. HLB value is estimated and usually given as HLB range.
    Total HLB - 6 Completely arbitrary number

    As I understand the HLB values of the emulsifiers and the oil phase are totaly unmatched So what? If it's unmatched to one side, it doesn't mean too much. If it's unmatched to the other side it only means that maybe/probably the emulsion is inversed or if not, potentially unstable. But, the emulsion is perfectly fine, stable with a great sensorials. The question is why?

    The second combination :
    Ceteareth - 25 - 0.5% One of the emulsifiers where HLB can be applied IF you stick to very simple systems and by preference micellar emulsions types. GMS plus cetearyl alcohol pull it away from there which explains the no-longer applicability of the HLB system.
    GMS - 3%
    Total HLB - 5.6 ( This combination is borrowed from the Evonik's Teginacid's formulation giude)

    Again, stable emulsion and a great sensorial profile -  easy spreading, fast absorbing, no gloss, no stickiness. Again too far from the desired HLB.

    The third combination : (according to HLB)

    Ceteareth - 25 - 1.4%
    GMS - 3%
    Total HLB - 11.1

    The emulsion offcourse is a bit more liquid because of the redused amount of the GMS.  But the sensorial is totally different. It feels a bit "heavy" than the previous, also it tends to be more sticky and shiny. It also have a fast absorbtion time, but the overal feeling to the skin isn't the best.

    The questions here are two in general :
    1. How is it possible to get a stable and fully working emulsions which are totaly out of the HLB system? Because HLB is an obsolete system which only works in a very narrow setting. Other industries do no longer use it... cosmetics, when it comes to that part of the industry, simply has no interest and not enough budget to switch to better systems.
    2. Does the sensorial properties related with the HLB of the emulsifier system? High HLB gives heavy and more upleasant sensorial, low HLB more pleasant. Not, no correlation at all. Well, in theory: Low HLB = w/o emulsion = greasy feeling and high HLB = o/w emulsion = lighter/fresher feel. However, you can know as much by looking at the structure of the emulsifier or very roughly estimating the approximate HLB (that's btw absolutely okay and helpful).

    The same situation I got with the Lotionpro 165. Used alone it gives light, but unpleasant emulsions which tend to be sticky and glossy.
    To be honest I don't understand why's that.
    See text in italic.
  • @Pharma very good explanation. 

    Can you please explain this part a bit more.
    "f it's unmatched to one side, it doesn't mean too much. If it's unmatched to the other side it only means that maybe/probably the emulsion is inversed or if not, potentially unstable." 
  • vitalysvitalys Member
    @ggpetrov
    You may find this alternative system interesting to study - HLD system. 
    HLD | Practical Surfactants Science | Prof Steven Abbott

  • PharmaPharma Member, Pharmacist
    @Abdullah It means that the HLB requirement is often just a HLB minimal requirement. Overdoing it will still work (within a certain margin). If the HLB is too low in case of an o/w emulsion it will, obviously, turn into a w/o emulsion if possible (if not possible, the emulsion is usually quite fragile).
  • MarkBroussardMarkBroussard Member, Professional Chemist
    @ggpetrov:

    The HLB system was developed when using PEG-based emulsifiers.  It's the equivalent of the Comedogenicity Scale ... an ancient relic of an approach that has managed to linger for decades, but really aren't reliable systems. 

    If you have some spare time on your hands, calculate HLB, but as you proved to yourself.  Only one of your examples had a PEG-based emulsifier and the HLB calculated at 11.1 matched your lipid phase, but it yielded the least stable emulsion.
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
  • Thanks guys, I really appreciate your consideration. The truth is I already have some formulas that work quite well, but I wanted to make things in a more professional manner. Ofcourse usually for a base I use some prototype formulas taken from the manufacturers of a cosmetic raw materials, but the final formulas have "my own touch". This "final touch" is a result of a many experiments and it seems that it's the only way, at least for a homecrafter like me.
    @vitalys - thanks for the suggestion, but it sounds too hard for me. I have studied four semesters chemistry at the university, but it's still hard for me to understand that system.



  • PharmaPharma Member, Pharmacist
    edited August 8
    @ggpetrov In galenics classes during my pharmacy study 20 years ago, we still had to learn HLB. I never felt comfortable with it and it didn't make much sense to me (outside the PEG-derivatives), even back then. Also, it usually didn't work with more complexe formulations. When I found out about the HLD system (the link provided is the best resource you can publicly access and it's really nicely explained), things started to make sense. You don't have to understand everything ;) . However, application in cosmetics requires a bit more work because most EACN and Cc values of cosmetic raw materials aren't available and have a rather pronounced supplier-to-supplier deviation.
    The experiments proposed can be done with just a fraction of known values and still guide you towards a better product (good = stable, not necessarily = feeling good).
  • Outside of understanding what a water-in-oil emulsifier and an oil-in-water emulsifier is, I agree. 
    I see lots of home crafters using high HLB surfactants in a product when it is mainly oiled, and it just separates. 
    This is a great PDF to look at. http://http//www.scientificspectator.com/documents/personal%20care%20spectator/HLB_Basics.pdf
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