Thickening properties of cetyl alcohol

edited June 2017 in Formulating
Question about emulsions with cetyl alcohol: do they generally need some time to thicken, hours, a day?
I've worked with cetyl alcohol before, but only in E-wax combinations.
I used it now as a co-emulsifier (2%).



  • That depends on what's in the whole formula. The structure of cetyl alcohol in a system depends on  many factors. However, sometimes it takes time for thickening to occur.  Cetyl alcohol is not a good thickener compared to other things like HEC, Carbomers, etc.
  • @Perry,
    The moisturiser was bodymilk-thin, now about 4 hours later, it has thickened to a nice creamy structure. :)

    But... I've been really really stupid about something else...  :(

    Niacinamide is one of my favourite ingredients, no doubt. I totally forgot about niacinamide turning into niacin in an acidic environment.
    Do you know from which pH this happens? The pH of the finished and already packed (in a 'locked' airless dispenser) moisturiser is about 4.5
    Because of the addition of potassium sorbate I was totally fixed on getting quite below pH5... 
    I say 'about' because my pH meter states 4.4 and the pH strip looks 4.8. I just calibrated my pH meter, so I think it goes more to 4 than 5. I lowered it with a citric acid solution.
    I made, for my doings, quite a batch with 200 ml, with valuable ingredients, so I hope it will be ok.  :#

    Apart from the flushing, does niacin for the rest have the same benefits as niacinamide?

    Should I put this question in a new discussion btw?  ;)
  • @Perry
    About my question about the stability of niacinamide, I finally found more information. I don't think I have to worry, at least not for a few months for sure.

    The reason being is that this hydrolysis takes a considerable amount of time. At a pH of 2 and 90°C it takes over 75 hours to convert half of the niacinamide in to niacin. Heat greatly speeds up chemical interactions, and at normal temperatures this translates in to weeks, if not months.

  • @Doreen81 I didn’t see your last post before I started thinking about this.  I love Kind of Stephen, by the way!

    First I must say that any pH test strips, which give vague qualitative measurements, are inferior to the right probe or electrode for your applications.  I have several probes and electrodes, and one of my favorites is the Milwaukee MA918B, which is a glass refillable electrode you plug into meter of your choice.  I like it better than my similar Hanna ones, which are about double the price.  (The Milwaukee one is < 100 USD.)  So, given that you have the right kind of pH probe or electrode (for measuring emulsions with oils and silicones—many are not good with water + oils and higher viscosities), and that you keep it calibrated, always go with quantitative over the strips!

    I have made this exact mistake of pH too low causing reaction of niacinamide > niacin/nicotinic acid.  I also have done it intentionally in scalp treatment formulas.

    I will write down things for you, because I see from your other posts that you are very smart with attention to details and interested in rigorous science.  (There shouldn’t be any other kind of science!)  If you don’t know it, then you will like learning.  If you do, then maybe someone else will learn.  I learn so much here and try to return the favor when I can.

    The niacin flushing is caused by an inflammatory response releasing some prostaglandins (and other substances – histamines, etc.) that (among other actions) act as vasodilators.  But it is not generally bad.  It’s just that people don’t like the look and feel (which are temporary).  But in some applications the flushing/tingling might be desired, and you can focus on the concomitant “oxygenation with flushing.”  (People love the idea of oxygen to tissues, but you know that O2 is quite corrosive and can’t be said to be all good in all cases.  I find it odd how so many of the average people don’t make the connection between O2 and antioxidants, for instance.  But I repeat that I think you are above average.)

    Here is one of my pet peeves:  A widespread and unscientific meme is that “all inflammation is bad.”  A lot of cosmetics in fact imply as such, by harping on their anti-inflammatory ingredients.  It’s also implied in vitamins and food supplements industry.  Well, without inflammatory responses in our bodies all the time, we’d soon be assaulted to death by the environment.  So obviously it’s false to believe “all inflammation is bad.”

    The following is an oversimplification, but it is useful.  Think of acute inflammation = good/okay and chronic inflammation = bad.  Niacin flushing is acute inflammation, meaning that it resolves quickly.  Another example of something causing acute inflammation is proper and healthy exercise.

    By the way, the prostaglandins themselves are both pro- and anti-inflammatory.  A lot of people only think of the various prostaglandins as bad/inflammatory or pain-causing, but that is not the truth either.

    >>>  Per the cetyl alcohol, I would have to know your formula, especially your complete emulsification system.  There are several emulsification/thickener systems I use that start off super thin and runny, but over a span of hours to a couple of days thicken up a lot – some from runny milk to thick cream.  The thickening behavior depends on other non-emulsifier ingredients, too, as well as how and how long you mix your emulsions, and at what phase you add some ingredients.

    I keep exacting notes on formulations, and I would advise that you do that, too.  For instance, I will write down my formulation on one side of the spreadsheet, and on the other side I insert textboxes, where I write down all sorts of notes on process, timing, changes, and behavior.  I write down the notes as I go along, in my informal lab, because the best notes are contemporaneous and human memory is a very fallible thing.

    Oh, to prevent niacinamide reaction, I generally don’t go below pH = 5.50.  But I think you can go almost a point lower.  Maybe someone else knows exactly.

    Also, some buffers don’t act fast, so you need to wait the appropriate time to take final pH measurements.  If you need to bottle while more fluid, then reserve a bit in a dish for later measurements after reaction time.

  • the rate of hydrolysis also depends on the amount of acid and its strength

    at pH 2, you'll either have an awful lot of acid or a very strong acid present, so it's not representative of conditions found in a cream or a lotion
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • edited June 2017

    Thanks for your extensive answer.
    I agree on the pH testing, I prefer meters aswell. Point is, I’m only making stuff for myself, so I’m not ready (yet) to invest in the highly accurate professional precision equipment, like what I’m working with professionally.
    Because of that, I keep using strips next to the meter to have a kind of double check.
    Also my scale will not be as accurate as the ones I work with, but it does the job for my own concoctions.
    I can weigh a minimum of 10 milligrams on my scale, the accuracy is good enough for my homemade stuff. This type is used for weighing gold/diamonds etc. It also has a calibration function.

    Thanks for your compliment, I also do indeed believe in rigorous science only. And I sure am very eager to learn.

    It’s interesting to read the mechanism behind the niacin flushing. Inflammatory reactions are indeed not harmful per se to an extent. It’s a natural and helpful reaction of the body, which is the main reason I don’t easily take for example NSAID’s for this purpose. Personally, I also like the feel of blushing flushing. Not necessarily because of the increase of O2 to tissue, but it’s just an overall nice warm feeling. Maybe I’ll change my opinion when I once will be menopausal. ;)
    I do like to add  anti-inflammatory and soothing ingredients because of the benefits for eczema and rosacea.
    Personally, I don’t care much for all the supposed anti-aging, anti-wrinkle stuff. Maybe because I don’t have wrinkles at all, though I’m almost  40. And apart from tretinoin, I don’t believe the supposed effects of all those ingredients.
    My 3 sisters (I prepare stuff for them aswell) do have wrinkles more or less, but unlike them, I never sunbathe or smoke and I kind of have a strict skincare regimen just because the skin is an important organ and I like to care for all of my organs. Sadly I can’t convince them to give their whole skincare routine a thorough look, as the cleaning part is essential aswell. So is perseverance. Only apply a moisturizer once a week or something won’t do much either.

    But back to the niacin topic. I was wondering if niacin had any other bad effects on the skin. I can’t find much about niacin on the skin. Do you mind telling me for what reason exactly you put it in the scalp treatment?

    About your spreadsheet, I do it the same way. Like what I’m used to professionally. Indeed, a space where you can place notes. If something went wrong for example, it’s good to know the exact amount you’ve used since there always is a slight deviation within the perimeters you work with.

  • Thanks for this very interesting elements on the niacinamide hydrolisis. 
    What are your favourite anti-inflammatory/soothing actives apart from the niacinamide? Personally I like the effect of alpha-bisabolol.

  • @jeremien,
    Soothing anti irritant favorite actives of mine are oat, licorice, allantoin, α-bisabolol. These are, next to niacinamide, my main actives. I don't care much for supposed anti-wrinkle ingredients (maybe also because I don't have any). I focus mainly on anti irritants. They've always done the trick for me.
  • @Doreen81 - I'm curious, how do you know your anti irritants are having any effect?

  • @Perry
    I understand your curiosity, I'm not easily convinced myself either.

    I'm not exactly doing a double-blind placebo/non placebo group test here at home, but I hear positive sounds from family members aswell.
    My skin feels better since I've become a homecrafter and use anti irritants mainly. No more rosacea outbreaks.

    My biggest 'victory' was getting my husband to use my concoctions (not because they're homemade, just because he thought skincare for men is gay and girly). He had the infamous irritable skin after shaving and also had this stupid tendency of patting some alcohol based macho after shave on the whole face (cheeks, chin, neck).  :#
    Either he could stop complaining about the irritable skin, or try my moisturizer, which I simply labeled 'after shave cream' on the package. ;) 
    His skin has drastically improved since then, but.... I think it's just a combination of not using alcohol on the face anymore and the moisturizer.

    So, you've got me doubting again. I'll now start formulating a placebo.  :p   ;)
  • Yes, testing a placebo (blinded) is an important check to see if ingredients are really doing something or we're just fooling ourselves. 

    When investigating facts, ideas and whether something is true, Richard Feynman said it best...

    "The first principle is that you must not fool yourself and you are the easiest person to fool."
  • As a very general rule, I would give it 24 hours to see the fully thickening effects of any emulsion.  I have actually noticed a difference within the first 4 to 6 hours, 12 hours, 24 hours, 36, and even up to 48 hours, after that it seems to finish stabilizing and remains the same no matter what it's made up of (as a generality, so don't jump all over that statement).

    As a side note, because Cetyl Alcohol is a C16 (and the fatty alcohol equivalent to palmitic fatty acid), it will be a bit lighter and stiffer than the next step up, which is Stearyl Alcohol (C18 - the fatty alcohol equivalent to stearic acid), and is a bit denser, smoother... even though they are both common/good thickeners.

    Of course no matter what qualities they have on their own, all that matters is what you're combining it with, because the conglomerate is the outcome.

    Just let it sit for a couple of days before drawing any major conclusions.

  • @doctorbrenda

    You are totally right! About 2 days later, the emulsion had thickened considerably! From bodymilk-thin to a nice creamy texture, I just left it to see what would happen and did not add xanthan gum. It just needed more time to thicken.
    I will change the formula though, apart from the thickening there still are other stability issues.
  • Has anyone ever studied the effect of combining natural thickeners to emulsions that also contain Cetyl Alcohol? I am making some hard to thicken emulsions and I've tried a couple of natural thickeners but if they are very high in Molecular weight they thicken the emulsion too much. Has anyone tried HEC, CMC or other natural thickeners? My instinct tells me to try lower molecular weight natural thickeners but I don't know if these will do the trick or not. Also, if using natural thickeners, should I lower the amount of Cetyl and Stearyl Alcohol?

    Thanks for any help or insight that anyone can give me on this.

  • I have used only once HEC 1%  and it increased the viscosity a lot. It also gave a very pleasant appearance to the cream (creammy, soft). I was unsure to go with HEC or xanthan gum, but once I saw the result with HEC, I didn't even try xanthan gum. Currently the formulation is in the stability test, but it should do well. 
  • Thanks for the feedback EM. I was going to try HEC at 1% but you said it increased the viscosity a lot. Perhaps I can try 0.50% or 0.25%.
  • edited July 2017
    Yes it did, but I like creams with good viscosity. Also it depends on the formulation. Best thing is to start with 0.25%. 
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