Home Cosmetic Science Talk Formulating Post Emulsification techniques

  • Post Emulsification techniques

    Posted by Joshlin on March 28, 2023 at 10:16 am


    Can anyone provide any information or guidelines re: adding liquids (water) post emulsification? To what extent can I add water soluble actives after the emulsion is formed (emulsifying wax + water only, for example). From my understanding there is some type of critical mass that is established where liquid formula additions will go directly to the ‘droplets’, and this is why you can add heat sensitive preservatives at the end. Of course, this is a very small quantity for preservatives. I was more wondering about adding larger quantities.

    As an example, after the water + emu wax emulsion is formed, the product weighs in at 10oz, it is a very thick cream/body butter consistency. What percent of that 10oz can I add in a room temperature liquid form that will go directly to the established emulsion, dispersed, without breaking it? I understand that the sheer amount of different emulsification agents and their different properties is going to make answering this question a challenge. I’m really just asking for generalities and I have provided that the emulsified product is a very thick cream, and after adding liquid it would likely thin out to a lotion. Is this even good practice? Consistency and long term stability aside, is adding up to 50% (5oz water to the 10oz emulsion) even remotely feasible?

    ozgirl replied 6 months ago 4 Members · 6 Replies
  • 6 Replies
  • Joshlin

    March 28, 2023 at 10:31 am

    I actually think it’s important to specify to some extent the emulsification agents so that this question may make more sense. Accepted plant based emulsification ingredients that are not the production of isolation/lab extraction techniques suffer from a similar problem in that they all require heat, sometimes high, to formulate with. Lecithin + plant wax is an accepted, stable emulsion forming, and popular combination offered by suppliers. The most economical plant waxes include soy wax and rice bran wax. Some natural certifications require use such agents.

    However, when formulating with heat sensitive compounds, there is the problem that the water portion is potentially required to be heated in some cases (depending on the wax) all the way up to 190 degrees F. It’s not the end of the world, but it would produce a less potent product. To get a thick product without heating to such temperatures would probably be impossible. But perhaps, if the desired product is a light lotion, and you start with a very thick cream and then add the water phase, you could get that light lotion without the added heat!

  • chemicalmatt

    March 28, 2023 at 2:44 pm

    I am unsure of the problem statement here. What is the specific concern or dilemma?

    • Joshlin

      March 28, 2023 at 6:32 pm

      The problem is that I am looking to add the bulk of the water phase after the emulsion has already been created, as it is heat sensitive. Typically emulsions involving plant waxes require both the water and wax phases to be heated to over 180F and emulsified at that temperature before cooling. I am just asking about techniques to add most of the water phase at the lowest possible temperature. I am hypothesizing that once the emulsion is formed at 180F with maybe 15% of the total water phase, and is in a very thick consistency, that I could continue stirring in the rest 85% of the water phase as the temperature cools. Perhaps that would lead to a ‘lotion’ type product instead of a thick cream, but the temperature sensitive compounds won’t be affected.

  • bill_toge

    March 28, 2023 at 6:54 pm

    if you have a sufficiently stable emulsification system, you can easily add water-soluble material when cool, provided that you keep any high-shear mixing to the absolute bare minimum

    • Joshlin

      March 28, 2023 at 11:07 pm

      Can you briefly elaborate on the chemistry behind this? Pardon my lack of knowledge. Is this a function of the reduced melting point of the solution? E.g., melting point of wax is 180F, water is liquid above 32F, so as you combine them and then initiate the emulsion, the melting point of the total solution reduces to a point where you can add more water at lower temps and it will still ‘react’ with the emulsification agent/system? Or does it have to do with the droplet mass? Or something else? I just want to better understand for the future.

      And the ‘keep high shear mixing to a minimum’ part… Why would this be the case? Given that you would want the actives/compounds in the water phase to be dispersed and incorporated as evenly as possible within the emulsion. Wouldn’t you want to keep the shear on high?

  • ozgirl

    March 29, 2023 at 4:29 pm

    What ingredient are you using at that high of a percentage? I am assuming that you are using some sort of botanical extract that can’t be heated.

    I would suggest reducing this ingredient and increasing your water because you are probably not getting any noticeable benefit from such high levels and are probably just wasting money.

    If you share your formula you can get more help.

    The other option is to just use a cold process emulsifier.

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