Home Cosmetic Science Talk Formulating Shear or no-shear for cool-down phase?

  • Shear or no-shear for cool-down phase?

    Posted by Anca_Formulator on December 16, 2021 at 7:55 pm

    Hi,
    I am working with with the lamellar emulsifier Heliosoft (INCI: Glyceryl Behenate, Behenyl Alcohol, Lecithin), though my question extends to other liquid crystal emulsifiers.

    My oil phase is 15%, Heliosoft at 2% (2% can emulsify up to 20%), Siligel at 1%. After initial homogenizing, I am cooling the emulsion down to RT under stirring with overhead stirrer. I add my cool-down phase at 35 C. 

    *Is the liquid crystal structure still forming at this temperature, and if so is it strong enough to handle brief shear, or would shear disrupt the structure and destabilize the emulsion? 

    Alternately, is overhead stirring sufficient, or are the particles too big, possibly creating a less stable emulsion?

    The manufacturer formulation guidelines for Heliosoft say it can tolerate brief shear at the end of the process (meaning RT?).  I tried that (20 seconds) and the emulsion looked less smooth (also some accidental bubbles, I think air, or I hope air not oil!).

    My cool-down phase is 2% Na PCA or 
                                        2% Water Soluble Extract
                                        3- 3.5 % Oil Soluble Extracts (Including tocopherol and EO).
                                        

    When you work with liquid crystal emulsifiers, how big is your cool-down phase? What oil % range, what water-soluble % range? Under what type of mixing?

    Thank you
    /A

                                                                   

    ggpetrov replied 2 years, 5 months ago 5 Members · 11 Replies
  • 11 Replies
  • DAS

    Member
    December 16, 2021 at 9:09 pm

    No shear, low speed mixing with anchor blade with scrappers is the standard. Otherwise aeration is a nightmare.

  • Anca_Formulator

    Member
    December 17, 2021 at 4:45 am

    DAS said:

    No shear, low speed mixing with anchor blade with scrappers is the standard. Otherwise aeration is a nightmare.

    Thank you. I tried the overhead stir-only to incorporate 3% oil at 35 C.

    I used a microscope to look at particle size. It looked like there were some bigger particles among small ones, compared to the same emulsion with nothing added during cool down. Aren’t those bigger droplets more likely to cause instability? Thank you. 

  • Abdullah

    Member
    December 17, 2021 at 4:46 am

    @DAS is aeration the only problem?

  • ggpetrov

    Member
    December 17, 2021 at 7:11 am

    I always mix my emulsions after 8-12 hours. In my experience, 5 minutes of mixing with a Bosh clever mixx, drastically improves the consistency and the haptic properties. I’ve never worked with your emulsifier, so i can’t say anything in details. 

  • Abdullah

    Member
    December 17, 2021 at 11:24 am

    @ggpetrov what emulsifier are you using? 

  • ggpetrov

    Member
    December 17, 2021 at 12:07 pm

    Abdullah said:

    @ggpetrov what emulsifier are you using? 

    I use various emulsifiers, actually i don’t use only one in my emulsions. But anyway I think the consistency regulators - fatty alcohols, solid esters or butters need of this additional mixing. At least when we speak of a homemade emulsions.

  • MarkBroussard

    Member
    December 17, 2021 at 3:28 pm

    @Anca_Formulator:

    I can’t tell from the way you worded your description, but to clarify.  You should be first dispersing your lamellar emulsifier in the water phase where it forms the structure and then adding your oil phase to the water phase that contains the lamellar emulsifier.

  • Anca_Formulator

    Member
    December 17, 2021 at 6:00 pm

    @Anca_Formulator:

    I can’t tell from the way you worded your description, but to clarify.  You should be first dispersing your lamellar emulsifier in the water phase where it forms the structure and then adding your oil phase to the water phase that contains the lamellar emulsifier.

    I develop the Siligel in the water phase while heating. I heat both phases to 75-80 C. Heliosoft goes in the oil phase. I emulsify the oil phase in the water phase for 2 minutes (I’m making small test batches) Then I switch to overhead mixer at medium speed, all the way down to RT. I add cool-down at 35 C. 
    When does the lamellar network start forming, and when is it robust enough to tolerate shear?  

  • Anca_Formulator

    Member
    December 17, 2021 at 6:07 pm

    Abdullah said:

    @DAS is aeration the only problem?

    Well, I think it’s aeration I’m looking at, and that the tiny bubbles that showed up after I emulsified again at RT for 20 s are air and not tiny oil droplets.I did 3 freeze/thaw cycles and it passed, but I made this emulsion last week  so I don’t know what it’ll look like after 3 months at 45, or 1 year at RT. 

    It is my understanding that you can over-emulsify and ‘break’ the emulsion. What doers that actually look like: tiny bubbles or something else?

  • Anca_Formulator

    Member
    December 17, 2021 at 6:11 pm

    ggpetrov said:

    I always mix my emulsions after 8-12 hours. In my experience, 5 minutes of mixing with a Bosh clever mixx, drastically improves the consistency and the haptic properties. I’ve never worked with your emulsifier, so i can’t say anything in details. 

    I have that little Bosch ;-). I’m not using it much these days because it is so fast and you can’t adjust the speed, so I always end up with aeration. Do you find that it introduces a lot of air? How big are the batches you use it on?

  • ggpetrov

    Member
    December 18, 2021 at 2:46 pm

    It depends, but in most cases - 100-200ml. The trick is to put the head of the blender below the surface of the emulsion.

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