Formulating a lotion: Choosing the fats – THEORY pt.5

[Actually the title of this post should be CHOOSING THE FATS / THE SECRET OF THE GREASE-FALL!] 🙂

You have learnt which percentage of fats your cream should approximately have, according to what kind of lotion you want to create; now it is time to learn how to distribute the fats within the percentage you have chosen.

The choice of the fats and their percentage in the formula is of big importance because mostly from them depends the touch of the cream: the more you know about them, the better you will be able to formulate. But let me explain how 😉

I will talk firstly about the OILS, and later on I will briefly talk about butters and waxes.
When talking about oils (but this goes also for other fats) you do not want to look much at their so-called “miraculous” properties (I won’t repeat this often enough!); what you want to look at, instead, are their technical qualities:
– density,
– spreading ability,
– feeling on the skin/absorbing ability of the skin.

– fatty acids composition.

[Note: on the internet you can find slightly different data from what I am reporting here: mine is my personal sum up and what I believe to be the most correct data. You are free to make a research on your own and give more value to different data you find 🙂 ]

Density – tells us, surprise surprise, how dense an oil is. For example castor oil (dens. 0.96) is one of the most dense oils, while jojoba oil (to be very precise it is not actually an oil, it is an ester… but let’s think of it as an oil for now 🙂 ) is one of the least dense (dens. 0.869).
Spreading Ability – this concerns how the oils spread on the skin. Don’t be mistaken however thinking that the spreading ability will tell you which oil has a light impact on the skin: an oil can spread very lightly and, at the same time, give a greasy touch. How? Well, the spreading ability tells you how the oil, when spreading it on the skin, is going to feel like: if an oil is very dense it will feel like you hardly manage to spread it, a medium oil will spread quite nicely and leave quite a good feeling in the end, while a light oil will most likely spread very fast and, at some point, you will feel as if it actually disappeared (don’t be mistaken by this: very light oils are very likely to, after 5 or 10 minutes, appear again on your skin leaving you with a greasy face 🙂 ). Now I will give you some data examples: wheat germ oil is DD (very dense) which means it doesn’t spread much but it is quite a “thick” oil; peanut oil is classified as D (dense), meaning that it doesn’t spread very easily; olive oil is classified MD (medium density); Almond oil is classified as M (medium spreading ability); Borage oil is Fl-M (fluid-medium: spreads a little bit better than a medium oil); primrose oil, instead, is classified as Fl (light-fluid) and sunflower oil, eventually, is classified L (light).
Absorbing ability on the skin – As I was just pointing out, some oils “show back” on the skin even if in the beginning they spread so well that you thought they had disappeared 🙂 what we really need to know, in terms of what is going to show on the skin, is how do these oil absorb on the skin. I will bring some examples again: wheat germ oil – greasy; borage oil – a little greasy; macadamia nut oil – oily feeling; almond oil – oily feeling; olive oil – oily feeling; argan oil – medium; jojoba oil – good absorption; sunflower oil – good absorption.
[These factors can be said also about synthetic oils.]

Fatty Acid Composition deserves a bigger discourse and it is not too important for the explanation of the GREASE-FALL, so it has its separate post.

Now finally… THE GREASE-FALL   🙂

You have learnt that oils and butters are different in composition and in how they behave on the skin. But how to use this information when we have to formulate?
Well, imagine you have a rather oily face and you want to create a cream for it. You want a light cream, easy to spread and absorb… and you don’t want it to make your skin greasy at all. If you didn’t read what I just said about the spreading ability I am sure you would think “I will make a cream with light density oils!”.
Well… and that would be SO WRONG! 🙂 The cream would spread even too easily, it would feel fresh in the beginning but after 5 minutes you would be all oily once again.
And imagine you have a very dry skin and you would like to have a very rich cream: probably you are thinking to make it only with fats like, let’s say, shea butter… am I wrong? It’s a rich butter, it has high vitamin E content… nothing could be better than that.
Well… WRONG AGAIN 🙂 you would get a cream which is not nice to spread, leaves your skin white unless you try to spread it nicely and you wouldn’t feel hydrated as you wish.
So what is going wrong?
Well, it’s very simple said: you are not formulating a GREASE-FALL, you are just adding oils randomly! 😀

So what is this bloody GREASE-FALL RULE:
whenever you start formulating a cream and you are clear which purpose you want it to have, you have to balance the different kinds of fats! Every cream, to be a good cream, need all the kinds of fats!
So how to differentiate a light cream from a thick cream for dry skin?
This is the magic of the grease-fall rule. 🙂 The idea of using shea butter for dry skin is not bad, but you will have to add also all the other densities; let me show you an example:
let’s say our dry-skin cream will have a percentage of 12% fats, you can organize the fats like this:
1% beeswax (for example, very high in density and low spreading ability. Gives richness to the cream. Never exceed with waxes though)
6% shea butter (you could also do 2% mango butter and 4% shea butter… the point is to keep butters at 6% because they are more emollient than most oils)
3% argan oil (medium to rich oil)
1% borage oil (medium)
1% jojoba oil (very light)
This is just an example which I “invented” exactly now and I am sure I could do better but, once you get the grip of it, you will love changing and experimenting on your own, so don’t give too much importance to this; it is just to give you an idea of how to create a balanced grease-fall: you put the highest amount of what you need and then, like in a rough gaussian distribution, you add everything else in minor amount.
So here is an example of a grease-fall for oily skin:
let’s say we will make a cream of 5% fats (with 5% it is not easy to make a good grease-fall and it is also quite hard to tell the difference in a cream 🙂 but we try to be professional no matter what 🙂 ok? )
2% jojoba oil (or, if you want to use synthetic oils, there are some which are much lighter than jojoba oil: for example dicaprylyl ether. Always bear in mind that even if they are very light, if you use too much, they will show up again on the skin)
1.5% sunflower oil (light)
1% black currant oil (medium-light)
0.5% shea butter
As you can see the shea butter is extremely low in % but still it will help the cream to be more balanced in the end 🙂

I hope I managed to be clear enough about this matter because it is an important one! 🙂
Let me know if you have any questions! 🙂

27 thoughts on “Formulating a lotion: Choosing the fats – THEORY pt.5”

    1. I’ve been having a problem with my creams where they just don’t rub in very quickly – I get the white streaks for ages – in terms of the oils – I am wondering if I have too many different ones and if I should just stick to 2-3 different oils


      1. Mostly the white streaks are caused by the thickening or emulsifying agents. Stearic acid or cetearyl acid for example.
        It is not a matter strictly about HOW MANY oils, but definitely which combination.
        Also, check your humectants. Maybe too much glycerin? 🙂
        You just have to tweak your formula.


  1. this is one of the most comprehensive blogs i have ever read regarding DIY cosmetics. i will definitely visit this blog on a regular basis. thank you so much. i can’t wait to start DIY-ing cosmetics.


  2. Love love love your posts, very informative. Do you have a table of various carrier oils and their density, spreadability, absorbing ability and fatty acids? I’d also love to see more of your recipes.


    1. I have it but it is on paper and I only summed up what I found online.
      There are some oils which have a different composition but, whatever the resellers claims, many oils are pretty similar (for example: hazelnut oil, almond oil, macadamia nut oil… they have a very different cost but their composition is quite similar).
      About density you can find information online (even though the data varies a little from one website to another), while for spreadability you have to make your own test by pouring a drop of oil on your arm or on paper (and waiting to see how it behaves). 🙂
      The same goes for the absorbing issue 🙂

      My recipes will come 🙂
      I am just formulating a face cream 🙂


  3. Love your blog. Thank you.
    I hope that with time i will get enough courage and knowledge to start making my own creams and lotions.. But first of all, the most important thing for me is to truly understand how it is made (or should be made 😀 ).


  4. Just loving your posts and learning!! I am a bit confused about the second example that you gave for dry skin formulation with 5% oils. You use 2% jojoba oil. I would like to confirm that is it for oily skin cream or dry skin? Or am i confused??


  5. I just discovered your blog, and it’s really great! This post in particular I found really interesting. I’ve been DIYing cosmetics for several years now, but I’d never heard of the grease-fall… so wonderful to learn new things!


  6. I love your blog!!!! I am so glad I’ve found this website!!

    I am a long time soaper (10+ years) and I have made toners and lotions a few times and even took a lotion making class. I have been reading your articles over 6 hours today, still reading :)!

    Your “Formulating cosmetics theory” and “How to Formulate Lotions and Creams” are so informative and so easy to understand! Your explanations are so clear that even someone like me could finally understood the basic of cosmetic making !

    I can’t thank you enough!

    Liked by 1 person

  7. You are a great teacher, I just discovered your blog, just reading everything I can for the past 6hrs. Please do you have any training or do you have any books on formulation that can help us?. Thank you

    Liked by 1 person

      1. But please can you recommend books that you read that was useful to you. Thank you


  8. Thank you so much for your incredibly valuable information. You have a wonderful way of breaking down the chemistry and steps involved in cosmetics. I am note taking and absorbing as much as I can after taking another formulating course this really made me understand it all more clearly. I am waiting for product to arrive to begin this journey and will continue to reference this material without a doubt!

    Liked by 1 person

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