ketchito
Forum Replies Created
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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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Preservation is arguably the single most important thing when developing a product that can be contaminated, like the mayority of cosmetics. Then, it’s our responsability to deliver safe formulas. For that, I’d advise you to get more education on the topic, like this book: https://www.amazon.com/-/es/Cosmetic-Microbiology-Philip-Geis/dp/0849314534.
You can alternatively watch this video: https://www.youtube.com/watch?v=3s5VTSHEucs.
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I believe @PhilGeis will give a better explanation, but Cetaphil used that combo of parabens for many years, since they are effective and safe (you can check the dermal info from their CIR and Opinions from the SCCP).
For the cleanser itself, if the product is more or less thick and foamy, then they made a lamellar gel (not a lamellar gel network since the oil part is missing), which is not only mild but helps retain more moisture on the skin due to the interlamellar water.
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Just in case someone is interested in good old evidence-based science, here are some interesting systematic reviews on the topic of supplements 🙂
1) https://pmc.ncbi.nlm.nih.gov/articles/PMC5227980/
2) https://www.ncbi.nlm.nih.gov/books/NBK72264/
And those are for the most studied supplements. The rest lack of sufficient evidence, and that gives room for all types of health claims.
pmc.ncbi.nlm.nih.gov
Our aim was to assess the efficacy of dietary supplements in the primary prevention of cause-specific death, cardiovascular disease (CVD), and cancer by using meta-analytical approaches. Electronic and hand searches were performed until August 2016. ...
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Propylene glycol is fully miscible in water and not in the oil phase. Also, the reduction on interacial tension of the water phase is marginal. That’s achieved by surfactants which have a hybrid structure able to interact with both phases, so I wouldn’t worry much about glycols on that regard.
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Sorry for chipping in, but I feel this like deja vu, hehe. Here are some systematic reviews (which are the best source of evidence):
1) This is an Opinion on Essential Oils from the EU SCCP: https://ec.europa.eu/health/archive/ph_risk/committees/sccp/documents/out218_en.pdf. In there, you can read the following:
“An important problem
with fragrance substances of ‘natural origin’ is the difficulty of quality control. There may be
considerable variation in the content of toxic/sensitising chemicals; oakmoss is an example.
There is no demonstration in the peer reviewed scientific literature that fragrances compounds of
natural origin are ‘safer’ than synthetics.”2) This is the Annex I to the same review “Clinical evidence regarding sensitisation to
individual fragrance chemicals and to natural extracts”: https://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_073_annex1.pdf. From the page 68 onwards, you can find a catalogue of natural extracts and essential oils.I was going to post more things, but I have to do husband stuff. Enjoy!
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Sensitivity to CAPB is very rare as shown in systematic reviews. In the case of sensitivity, you can of course choose to replace the ingredient, or a more chemical approach which is inactivate the impurities (amidoamines are responsible for the sensitization) by formulating more acidic products.
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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.
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I think @Aniela solved it. Probably the excess salt overall doesn’t let you build high viscosity (sec. viscosity curve). You could try the following formula:
Water q.s., CAPB 15%, Sarcosinate 10%, NaCl 1%, SCI 1%, NaSalicylate 0.4%, NaBenzoate 0.4%, Citric acid q.s. You’d need to reinforce your preservative system, and it’s always a good idea to add a chelant.
Add the NaCl little by little (like 0.2% additions) since you don’t know the salt curve of that mixture.
Sarcosinates are harder to thicken than SLES…perhaps you could try with Olefin sulfonate instead.
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Just to expand on @Fedaro ‘s good points, it’s different to have a sole surfactant (like a solution of SLS which is the way ingredients are tested) than to have a mixture of different types of molecules which interact between each other in a synergistic way to get milder products, higher viscosities, better deposition, etc. Anionic surfactants are usually combined with amphoterics or non ionics to reduce their irritation potential and sometimes increase viscosity. They can also be combined with cationic polymers for the same (plus extra conditioning through coacervation). That’s one of the reasons why EWG’s classification fails to reflect what really happens inside a product.