How to make a lotion: EMULSIFIERS pt.2 – THEORY

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In the previous post about emulsifiers, we talked about HLB and how it mainly tells us whether an emulsifier is more lipophilic or more hydrophilic. Useful information, of course — but not the whole story.

What usually matters more, when trying to understand an emulsifier, is:

  • the conditions under which it is typically used (for example, hot or cold process),

  • and the percentage range in which it generally works.

These aspects are not the same for every emulsifier. Even emulsifiers with a similar HLB can behave very differently, which is why the amount used in a formulation can vary quite a bit from one to another.

This kind of information is usually easy to find at the moment of purchase. Suppliers normally indicate recommended usage levels and processing conditions on the product page. When that information isn’t available, it’s often a good idea to ask the supplier directly — clear documentation is usually a sign that the product is well understood.

With that in mind, here’s a general overview of how emulsifiers are commonly grouped and described.

Hot-process and cold-process emulsifiers

One of the main distinctions between emulsifiers is whether they only show emulsifying activity when heated, or whether they also work at room temperature.

Emulsifiers that require heat are usually solid and often sold in flakes or pearls. Their emulsifying ability is typically associated with temperatures around 70 °C. When the oil and water phases don’t reach this range, emulsions formed with these materials often turn out unstable and may separate over time. For this reason, temperature alignment of the phases is generally considered important when working with heat-dependent emulsifiers.

Since many commonly available emulsifiers fall into this category, a lot of formulation examples describe a process involving heated phases, followed by emulsification and cooling before adding more sensitive components.

Within this group, emulsifiers can be more lipophilic, more hydrophilic, or self-emulsifying. Looking at the INCI or product description usually gives a good idea of whether an emulsifier tends to work on its own or is commonly paired with a co-emulsifier.

Just to give a couple of familiar examples:

  • Methyl glucose sesquistearate is often described as more hydrophilic and commonly paired with a lipophilic co-emulsifier.

  • Montanov 68 is generally considered self-emulsifying, since its composition already includes both lipophilic and hydrophilic components (cetearyl alcohol and cetearyl glucoside), and it is typically associated with hot-process systems.

Many formulators find that combining separate emulsifiers, rather than relying only on self-emulsifying blends, offers more flexibility in terms of texture and skin feel, once they become familiar with how each emulsifier behaves.

Learning through comparison

A frequently mentioned way to understand emulsifiers better is by observing how different ones influence otherwise similar systems. Looking at changes in texture, stability, or skin feel across comparable bases can be very informative and helps build a practical understanding of what each emulsifier brings to a formulation.

“No-heat” emulsifiers

Emulsifiers marketed as “no-heat” are usually liquid or semi-liquid and maintain emulsifying power at room temperature. Products made with these emulsifiers are often described as lighter and less rich, partly because working without heat limits the use of solid butters and waxes.

That said, some “no-heat” emulsifiers can tolerate gentle heating, even though heating isn’t required for emulsification. In these cases, the supplier’s documentation usually specifies acceptable temperature ranges and compatibility with solid lipids.

As always, supplier information is the most reliable source when trying to understand how a specific emulsifier behaves.

That’s it for this overview of emulsifiers.
If you have more specific questions or want to dive deeper into particular types, just let me know 🙂

Have a great day! 😄

(Sources)

15 thoughts on “How to make a lotion: EMULSIFIERS pt.2 – THEORY”

  1. Just read through the entire series of the formulating posts – thanks a lot for great ideas and explanations!

    I am just starting to learn how to make emulsified cosmetics, and your posts have been very very helpful!

    All the best,
    Veronika

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      1. Hey and thanks for replying so fast! Yes, it’s all pretty clear so far! I’ve been reading Point of Interest, too, but I liked some of your explanations better (like about the Grease-Fall, for example). So far I’ve made a jar of really really thick (I wanted it that way for Finnish winter) body butter with almond and coconut oil and some sea buckthorn oil and vitamin E on rosewater base, emulsified with e-wax which contains some cetyl alcohol. It is lovely but it took forever to thicken – more than several days.

        I am planning to make a facial cream next, so I might well be back here with silly questions! Hm, speaking of one – what do you use to test pH? I don’t have a pH meter at home (I’m a food biochemist, so I have used it at work but they are bloody expensive).

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      2. Oh I simply use pH stripes!
        Not those which are all yellow (they are not precise) but those which have at least 4 different colors to check! (I hope I explained myself decently 😀 )

        For the body cream… it always works this way: if you want an almost liquid cream which can be poured through a lid, it will 99% come out a thick cream 😀 if you want it thick, it will remain quite liquid! 😀 It is THE MURPHY EFFECT! 😀
        But ok, lately also the cetyl alcohol which I have been using is of this kind: it takes many days to thicken and unless you keep the cream in the becher, it won’t thicken in a homogeneous way.

        ps. Finland! I am going to Finland in few days (I used to live in Oulu but now it’s already three years I am not back there and I was missing it too much!) 😀

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    2. Thanks for your Posts. They are very helpful to me. I’m trying to make a Lipophilic Niacin
      cream, and I didn’t take much Chemistry in school. I want to use the cream on my Bald Head,
      LOL……. Niacin Tablets can be bought at the Drug Store. I don’t know how to formulate the Cream and to mix in proportions of Niacin or how to make Niacin Tablets liquid.
      Any suggestions, like what type of cream to use, etc, you could give me would be greatly appreciated.
      Regards,
      Abe
      jopa1493@yahoo.com

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      1. Hello Abe! 🙂
        A cream is neither lipophilic nor hydrophilic in the way that it is an emulsified compound 🙂 it both contains emulsified lipophilic and hydrophilic heads.
        This said 🙂
        For the tablets you buy, you must be sure of their composition: probably they are not 100% niacin and therefore it won’t be easy to calculate how much to use in your cream (or even to know IF it is possible to “melt” the tablets in water).
        The easiest thing you could do is to buy it pure (online for example).
        However I suggest you to first learn to make a simple cream and THEN try to use Niacin.
        This is because it is not so simple to formulate with niacin since it can become an acid and it actually does the opposite of what we use it for.
        But why would you put a niacin cream on the head? 🙂

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  2. Aha! Thanks, I should check amazon or pharmacies for those!

    As to body cream – it thickened up beautifully after I went on vacation and came back 2 weeks later, uniform and totally gorgeous and I will make a bigger batch next time. It’s just that I have no idea how long it took – more than 3 days but less than 2.5 weeks? I will try to be patient next time, and not assume I’ve failed till I gave the product enough time to ‘settle’.

    Oh, you are coming to visit? Where from (if you don’t mind me asking)? Are you planning to buy sea buckthorn oil while you are here – it’s cheaper and better than any I’ve seen anywhere else! We are in central Finland because my bf got a job here teaching in a university, so we moved here from Stockholm. It’s really nice, though mid-winter it does get pretty dark. And this winter was awful with no snow that stuck around so far – I am hoping it improves soon!

    My in-laws gave me a bottle of (the ridiculously expensive) Rose de Mai absolute for Christmas. I need to figure out a good facial cream recipe to use the precious stuff in!

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    1. I am from Italy but at the moment I am in Germany 🙂

      I will look for the buckthorn oil definitely! And thanks for telling me as I didn’t even think about it! 🙂

      In making face creams I think one gets always tempted to add ALL the good active ingredients one can find… But often it is best to add only those few which combined will work in synergy! 😀

      Ps. NO!!! If you thought you did something wrong, not at all: some creams take even 10 days to thicken! 😉

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  4. First off, thank you so much for all your quick replays. Your comments and website have been incredibly helpful! Sometimes I learn even more just by reading through all the comments. I’m a jeweler in the states http://www.ellisofficial.co. I used to make body products and sell them and now my boyfriend wants to! Haha.
    Anyway on to my question. I didn’t see any waxes on your emulsifying list. I always thought that mediums such as beeswax or vegetable wax were emulsifiers. No? Yes? Because I try to stay more “natural”, I’d prefer to continue using those two items if they are emulsifiers. I’d like to be sure I’m using them correctly, tho! Also, I have some liquid lanolin, and it’s considered an emollient. What is the difference between an emulsifier and an emollient, and how can I use them together in the same product?
    Sorry for all the questions, you are the best!

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    1. Hello Lauren.
      No, beeswax is not an emulsifier.
      It is merely a thickener.
      It can keep a small amount of water together with a great amount of oils/butters but what happens is mostly a mechanical effect (you keep mixing until cool down and what happens is that the water particles are eventually trapped and kept separated… but it won’t last for long) and it is not a real emulsification.
      There are many real emulsifiers which are ecocert and you could use those.

      “Emollient” is not related to emulsification, it simply means that it softens the skin. Usually oils and butters are emollient… which is different from moisturizing (oils and butter cannot moisturize) and that is why we emulsify oils/butters with water: to create a cream that is both emollient and moisturizing! 🙂
      I have never used liquid lanolin but I guess it can be used in the oil phase (just keep in mind the density of it and make a balanced grease-fall).
      Hope this helped!

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      2. I have never tried a specific ecocert emulsifier (usually they are self emulsifying, which means that they are already a combination of two emulsifiers: hydrophilic and lipophilic) so I cannot really suggest you any. But they are quite easy to find: maybe purchase a few (in small amount) to make your experiments and pick the one you like the most! 🙂

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  5. Hi, thank you for running this site, it has been very helpful to me. I am making my own lotion for my face. I have found that I am allergic to many ingredients and I have come across this https://www.aromantic.co.uk/home/products/emulsifiers/biogreen-emulsifier-(palm-free).aspx which looks ok to me. I have bought it and made a cream but I was allergic to the preservative I used (I think!) so have bought a new more natural preservative and I’ll give that a go. I just wondered if it this emulsifier is fine just to add? I am reading a lot about needing to match the HLB values. BioGreen has a HLB value of 15 and I am using MCT oil as my the only oil in my lotion, which has a HLB value of 5. But I can’t seem to find the need to balance these with BioGreen. Have I got that wrong? Should I be adding something else to lower the HLB value? Any advice would be really helpful to me.

    Matthew

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    1. Hello Matthew!
      I have never used the HLB theory too much to be honest: the calculations are correct only if you use ethoxilated emulsifiers and if you don’t you need to be able to evaluate the results (too complicated for the interest i had in it).
      However HLB 15 means that the hydrophilic-lypophylic balance of the ingredient is highly towards the hydrophylicy (if that’s a word 😀 ).

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