Home Cosmetic Science Talk Formulating About cream hardening….

  • About cream hardening….

    Posted by asafvarlix on December 4, 2019 at 5:31 pm

    Hello everyone,
    I would please like to know
    Why creams becomes hard after a day or two?
    it’s a phenomenon i know some years by the name “cream settling”  - but i don’t think its the professional term.
    we’re talking strictly about O/W creams,
    So why creams become hard a day after the preperation cease?
    Is it Ostwald ripening? is is flocculation? or is it something else?

    Im asking becuase I want to read further about it…
    Any help will do. 
    Cheers!

    doreen replied 4 years, 3 months ago 6 Members · 11 Replies
  • 11 Replies
  • oldperry

    Member
    December 4, 2019 at 5:36 pm

    Could you give an example of a cream (ingredient list) that does what you’re talking about? When I worked on the St. Ives brand nothing like what I imagine you are talking about happened.

  • bill_toge

    Member
    December 4, 2019 at 9:10 pm

    if you mean the increase in zero-shear viscosity that occurs on standing for 12-24 hours, that’s a result of the surface-active waxes (cetearyl alcohol/stearic acid) recrystallising into their most thermodynamically stable state following formation and cooling of the emulsion

  • asafvarlix

    Member
    December 5, 2019 at 7:33 am

    Dear Perry & Bill, Bill got that precisely right -
    Its happening with Cetyl alcohol, stearyl alcohols and stearic acid.

    What’s the “name” of this phenomenon - should one exist?

  • bill_toge

    Member
    December 11, 2019 at 9:25 pm

    Dear Perry & Bill, Bill got that precisely right -
    Its happening with Cetyl alcohol, stearyl alcohols and stearic acid.

    What’s the “name” of this phenomenon - should one exist?

    a technical description would be that the surface-active waxes initially exist in a kinetically stable/metastable non-equilibrium phsyical state within the emulsion, then recrystallise into their most thermodynamically stable state over time

  • helenhelen

    Member
    December 12, 2019 at 10:23 am

    I’m also interested in this. How can we stop creams stiffening over time?

    In my case, one of my recent cream samples from the chemist stiffened significantly after a few weeks, making it difficult to spread on larger areas. The minor changes from previous samples were reducing the oil content slightly (from around 21% to 19%) and swapping xanthan gum out for sclerotium. We have used sclerotium for other samples and didn’t get the same issue but this is the first time we’ve reduced the oil content at the same time (which was an improvement on the oiliness on application).

    I was thinking to reduce the gum. It’s currently at 0.5%. Would this help? As I’m working with chemists and not formulating myself, I’m limited as to what I can test within the time and costs, so am trying to narrow the tests down to one or two… 

  • ngarayeva001

    Member
    December 12, 2019 at 11:23 am

    You need to account for this effect when you formulate that’s it. Add less fatty acids/alcohols in your formula having in mind that the product will gain final viscosity only after a couple of days.

  • bill_toge

    Member
    December 14, 2019 at 9:56 pm

    You need to account for this effect when you formulate that’s it. Add less fatty acids/alcohols in your formula having in mind that the product will gain final viscosity only after a couple of days.

    +1 for this; it’s controlled by thermodynamics and can’t be prevented

  • doreen

    Member
    December 15, 2019 at 3:35 pm

    (…) having in mind that the product will gain final viscosity only after a couple of days.

    I’ve seen this brought up many times, that you gain final viscosity only after a day or 2 if you use fatty acids/alcohols, but I’ve never experienced it myself. Viscosity right after cooling down has always been the same as a few days later. And I’ve made quite some creams with cetyl/stearyl alcohol and the likes.

    Isn’t that what’s been described not actually a cream drying out? How is the packaging? A jar? 

  • ngarayeva001

    Member
    December 15, 2019 at 5:28 pm

    This is my personal rule of thumb but if I deal with cetearyl alcohol in particular 3.5% gives same viscosity in several days as 4% right away after cool down. So I always discount 0.5%

  • bill_toge

    Member
    December 19, 2019 at 11:28 pm

    Doreen said:

    (…) having in mind that the product will gain final viscosity only after a couple of days.

    I’ve seen this brought up many times, that you gain final viscosity only after a day or 2 if you use fatty acids/alcohols, but I’ve never experienced it myself. Viscosity right after cooling down has always been the same as a few days later. And I’ve made quite some creams with cetyl/stearyl alcohol and the likes.

    Isn’t that what’s been described not actually a cream drying out? How is the packaging? A jar? 

    this happens in sealed containers at low temperatures (if anything, low temperatures accelerate it); water has low vapour pressure at room temperature and below, so not enough of it can escape to cause a significant drying effect

  • doreen

    Member
    December 21, 2019 at 6:55 am

    @Bill_Toge
    Ok, thanks! I use rather low levels of fatty alcohols/acids in moisturizers, maybe that’s why I don’t see it (the cream reaching a higher viscosity after a few days) happen.

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