ketchito
Forum Replies Created
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Hi! No worries….and I think you’ve got a nice answer on that other post 🤓. For what you described, there shouldn’t be any issue.
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Not sure I can remember everything, hehe, but I’ll do my best. GMS, cetearyl alcohol and stearic acid (non neutralized) fall in the same conversación. Rather than being low HLB emulsifiers, they are structuring agents. Let’s put it this way, if Beyoncé is the high (very high) HLB emulsifier, Jay Z (for better or worse) would be her low HLB emulsifier, meaning that in an emulsion, they would have more or less equivalent positions. What happens with GMS, stearic acid and cetearyl alcohol is that, when forming a lamellar structure with the high hlb emulsifier, they will occupy the corners of an hexagonal arrangement, leaving the central stage to the high hlb emulsifier.
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Have you tested a similar product with that amount of niacinamide? I used a cream for sun spots that have niacinamide at around 3-4%, and it was stinging at the start (in the instructions, they even mention that the cream can cause some temporary redness of swelling, which is common in niacinamide containing products). Now, 10% is quite a lot, and if the pH is low and it hydrolyzed to niacin, it could be even more stinging.
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That could mean that the H2O2 was not evenly distributed, which is then corrected after mixing.
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As @graillotion said, the amount of energy (time and speed) is formula and reactor-size dependent. Formally, when you go from lab to plant, you’d need to calculate different parameters like BTO, power number, heat gradient, etc.
As a general rule, for a regular O/W emulsion with waxy emulsifiers and structuring agents, and a decent amount of oil phase, for a 50gal batch and one high-shear homogenizer, I’d emulsify close to 80C and with high shear for close to 10 min (it should be a bit less when increasing the diameter of your homogenizer compared to the diameter of your reactor), then I’d switch to a helical mixer. If the product is lighter (like a lotion with few and soft waxes), I’d cut the emulsion time to 5 min under high shear.
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If I had the budget, I’d use Cetyl HEC. Not only it gives you more stable emulsions (I had some phase separation when using HEC, which was fixed when using Cetyl HEC instead since it interacts more with both phases which HEC doesn’t), it has a more pleasant feel when spreading (not a huge difference, but at least perceivable).
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Oh, I’ve got it. And why can’t you change the manufacturing process (that’d be the easiest thing to change, unless you require some specific equipment)? If all your materials are liquids (I see no need to heat then), you can add some polymeric emulsifier to make your emulsion more stable (like Sepigel 305).
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@abdullah Did you have the same turbidity with 4% of STPP than with 0.5% of STPP?
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I’ve worked with peroxide-based formulas in the past. To mitigate conditions that can impair their stability, you need to first keep a low pH (a pH below 4 is recommended) and use chelants (diphosphonates -like HEDP- are the best for the job, but not so popular in cosmetics).
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STPP for sure has a better performance at pH higher than 7. Now, to keep the pH after dilution, you could instead use a buffer. But first check if it’s the higly basic NaOH the source of your problems.
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Hi! Yes….the part your posted about the pH is what got me thinking 🤓
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Can you make a sample without sodium hydroxide? Sometimes STPP can hydrolyze in the presense of strong bases. Also, 4% of STPP is quite high, even for a very high water solution. I’d start with a lower amount to see if there’s precipitation (of course, only after the original precipitation issue has been solved).
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Any chance you can keep the pH over 6.5? My guess (very uneducated some times) is that at a lower pH, some groups in the polymer get protonated, leading to intermolecular hydrogen bond formation, some coiling and loss of solubility, that’s why the precipitation. Again, this is just a guess.
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The fact they are paired together has to do with packing. That’s why PEG-100 stearate goes with Glyceryl stearate, or Ceteareth-20 goes with Cetearyl alcohol. They are like perfect marriages (as if Henry Cavil marries Amy Adams). You could use a different structuring agent, but it’s like being with a husband/wife which is not your perfect match. You could try with a 4:1 ratio structuring agent/emulsifier, and screen it up to 2:1. If you want to be more precise, you could calculate the crystal parameters of each molecule, but I believe a 3:1 would be a safe bet.
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A consumes once came to me saying that she liked one of the conditioners I gave her, but not the other. When I told her they were both the same formula, she was schocked, so, one consumer opinion shouldn’t force you to change your formula.
Btw, wherever you put Glycerin in a cleanser, it’ll always impair surfactants performance, especially foam.
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What you were doing was adding something to solubilize the vitamin, which is the easiest way. Your could try with other materials to solubilize your vitamin, if you don’t want to use your current one. A pre-emulsion sounds to me more like a W/O microemulsion (you need tiny droplets not to interfere with the appearance of the oil). But that’s more complicated (and costly) than using something to solubilize the vitamin.
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@Bobalooey You might want to take a look at the paper I’m attaching, especially the conclusions. Unfortunately we are all biased when formulating, that’s why we run tests with more people (and that’s why it’s a good practice in trials to make them double blinded).
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I don’t have experience with that system, but you can make a test bringing the pH to 7 (SSG would be fine, especially since it’s a basic salt and at higher pH, it’s be in its active form to emulsify).
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What’s the final pH your achieving with SSG and Carbomer?
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@mikethair I’m also very sorry for what happened. All my best wishes.
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Those ingredients have more chances to resist if they are in solid/powder form, in a tightly sealed package (inert gas should be a lot to ask, but at least some vacuum would be nice) and not exposed to direct sunlight 🤓
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I wanted to chip in on @Aniela‘s nice metaphor with a funny comment, but I woke up with zero creativity today 😅. I’d first start with including both Dimethicone and Black Seed Oil to the oil phase and removing (or bringing up to 0.01%) your Irish Moss Extract. It’s best to have all the oily-heat resistant-ingredients in the oil phase since oils within micelles oxidize less that free oils. Now, it matters which type of mixer you’re using: a high shear homogenizer works best to create more homogeneous emulsions, while low shear would probably leave part of your oils as free oils in your system (and more prone to oxidation). Now, I like the knight metaphor, only Tocopherols are more like Lord Farquaad (cheap reference to my favorite Shrek movie), while something like Tinogard TL is kinda Christian Bale in The Dark Knight (sorry no sorry Ben Affleck). I believe nature was a bit lazy when synthesizing Tocopherols and didn’t want to handle some nice amines and a couple of more cyclization reactions…but she (yes, she) made Henry Cavil and Amy Adams, so it’s fine.
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Buffers are formed by an acid and its conjugate base (in this case, it should be citric acid-sodium citrate, but it dependes on the pH you want to keep).
Nevertheless, if removing NaOH didn’t fix the issue, then the problem is different. Can you make a sample with only 0.5% STPP to see if the amount of precipitate is less? Also, usually you mix SLS with SLES at a ratio of 1:2 or 1:3 to reduce water hardness sensitivity of SLS.
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That’s interesting. Lubrizol’s MGS is primary a W/O emulsifier, while Evonik’s is a O/W emulsifier (that’s why the antagonistic HLB values). My bet is that they are both different emulsifiers (while Lubrizol’s has only one glucose unit, Evonik’s might have few of them. increasing the polarity of its head group, its solubility and hence its HLB). Then, you could pair them (a 4:1 ratio as a starting point still holds). Lets’s see how it goes.
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I support @evchem2 comments. Your formula looks more like a low foam shampoo. Co-washes are the closest to what you want to formulate, but keep in mind that washing your hair with a rinse-off product with good detergeny is key for a healthy scalp. I recall some TRI presentation on the topic of scalp, and the need for washing the hair/scalp regularly.