Pharma
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As a rule of thumbs, 5-10% of total emulsifiers/co-emulsifiers should suffice. An exception to this rule may be lamellar gel networks and α-gels where >20% weak anionics (such as glyceryl stearate citrate) may be included. However, in that case, the anionic emulsifier is often combined with fatty alcohols (about 1/6 to 1/10) and non-ionic emulsifiers with large hydrophilic head groups may be included to increase stability (in that case at +/- 10% of total amount of emulsifiers/co-emulsifiers).
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Sorry for hijacking this thread but I think the titel is so compelling that this option seems better than starting a new one.A sales rep from Bayer dropped by yesterdy with the new Bepanthen/Bepanthol DERMA line… preservative free as they claim… glycerol and 1,2-hexanediol were in there as humectants/emollients, not preservatives, they say. Anyway, there’s nothing else in that line which would preserve anything. And it doesn’t look (though I don’t know) like they were using airless systems either.Here’s a copy-paste of the LOI of one of those products (the others are nearly identical in composition):Bepanthol® DERMA Regenerierende Körperlotion:
Aqua, Caprylic/Capric Triglyceride, Glycerin, 1,2-Hexanediol,
Butyrospermum Parkii Butter, Panthenol, Squalane, Isopropyl Isostearate,
Isosorbide Dicaprylate, Niacinamide, Cetearyl Alcohol, Polyglyceryl-6
Distearate, Jojoba Esters, Tocopheryl Acetate, Glyceryl Stearate
Citrate, Behenyl Alcohol, Argania Spinosa Kernel Oil, Polyglyceryl-3
Beeswax, Cetyl Alcohol, Xanthan Gum, Acrylates/C10-30 Alkyl Acrylate
Crosspolymer, Citric Acid.I have a hard time believing that Bayer would put an ‘unsafe’ product on the market but I also have a hard time believing that these products are properly preserved. What do you think (reaching out to @PhilGeis)? -
Olive leave extract isn’t one substance and it’s not even clear, what kind of extract it is… Even if you’re always using the same product but different batches, they’re never the same. IR may be suitable to a degree such as: band this or that has to be present (representing for example a major typical constituent) or has to be absent (typical peak of a spiked extract). Organoleptic should work though.In general, natural product mixtures are not too well suited for IR and citrus peel cera isn’t much different. Given that oranges don’t have a super strong variation in their composition, maybe you could make your own reference spectrum from a batch you identified by other means.Bentonite is another mixture (and a solid)… not sure if that one can be IR’d…
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Abdullah said:…My question is, does viscosity of lipid phase has any effect on emulsion stability?
…Yes. Purely stability-wise, higher inner phase viscosity makes an emulsion (or rather the oil droplets therein) more stable regarding coalescence and Ostwald ripening.
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Higher % alcohol can result in wrong pH readings with certain glass electrodes.However, ethanol does not really affect pH and you can as well set the pH before adding alcohol
.By preference, use a ‘buffer’ which is soluble in 75% ethanol. However, there aren’t too many cosmetically suitable buffers which work around pH 5.75-6… there aren’t too many biologically compatible buffers in that range anyway. In addition to that, for most of those the charged forms aren’t soluble in such high amounts of ethanol.A: it would be wise to use diisopropylamine or alternatively aminomethyl propanol aka AMP-95 as ethanol soluble base.B: you’d now ‘only’ need to find a suitable buffering acid… alas, there aren’t too many to choose from… carbonate would be suitable at pH 6 upwards but you might run into difficulties working with dry ice as starting material. Acetic acid would be easier to handle but only works up to 5.6. Short to medium chain fatty such as caproic, capric, or caprylic acid would be better suited due to their good solubility in ethanol (in their acid form but also likely in their salt form). On the flip side, the product would reek like a horny goat. Hence, lauric acid and an ethanol soluble amine would be my pick (please note, such carboxylic acid buffers will only buffer to a pH of <6 and hence will only poorly protect a rise in pH whilst buffering well against pH lowering).C: If you opt for the opposite combo of a buffering base with a strong acid, the acid part is fairly easy to cover but the base part… derivatives of imidazole, pyridine, and aniline come to mind. Sadly, most of the ones soluble in ethanol can’t be used if you value your customers health (and, again, their olfaction). -
@Bill_Toge I’m not sure that this is the case. Benzophenone radicals are quite reactive, hence their use as radical initiators in polymer synthesis and the like.The ketyl radical is sterically hindered but the whole benzene rings aren’t. Oxybenzone and benzophenone-4 are mesomery stabilised phenolics, not sterically hindered ones. IMHO is their only job that as UV screens, they shouldn’t get sp excited that they form radical species.And because they aren’t good antioxidants, they can’t regenerate oxidised vitamin C. I’m not really familiar with radical chemistry. My understanding is that photoexcited benzophenones can react with molecular oxygen which results in non-excited benzophenone and oxygen radicals and that doesn’t sound good to me. In theory, photoexcited benzophenones could quench other radicals… However, ascorbic acid degradation isn’t typical radical chemistry aka one electron redox reactions but two electron reduction/oxidation (one of the reasons why tocopherol can’t recycle oxidised ascorbic acid). Maybe you could shed some light on it?
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Metabisulfite, dithionite, and a few thiols are the only cosmetical antioxidants which are stronger than ascorbic acid and are capable of recycling/reducing oxidised ascorbate. Phenolic antioxidants such as tocopherol will not rescue vitamin C but show in vivo synergism. The former are also better at capturing the causing agent (oxygen) and don’t just ‘remedy’ damage or quenche chain reactions.
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In theory, acidic preservatives would get more efficient at a given pH when their pKa increases .However, a change in apparent pKa can also mean that water-to-oil/micelle distribution is shifted towards the interface or even into the micelles which corresponds to less available surfactant in the water phase and potentially lower activity (similar to the incompatibility of parabens with PEGs).It is impossible to judge the reality only based on the data provided… one would have to measure antimicrobial activity.
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Nicky said:Okay, thank you. What preservatives do you suggest I use in combination with potassium sorbate?Depends of the ingredients. The traditional (old) partner for sorbate is benzoate. Still commonly used for foods and less susceptible cosmetics. A better combo would be with phenoxyethanol.Sorbate shouldn’t be used above 0.2% (which is the legal limit in several countries) due to adverse skin reactions at higher levels.When using acids/salts such as sorbate or benzoate as preservatives, keep your pH as low as possible (<5ish).Usage: Add the required amount of potassium sorbate to water. It’s a water soluble salt, it will dissolve easily.
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Add more glycerol.Reduce potassium sorbate down to 0.2%, 0.5% might cause skin irritations (and is prohibited at that level in several countries).Also, adjust pH best below 5 or your preservatives won’t work properly. However, based on the ingredients, the benzoate/sorbate combo might not suffice.1% allantoin is too much, it’s not soluble at that concentration and just wasted.
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Do you follow their recommendations or are you using your own strategy?
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@Graillotion I suppose that’s the reason why.
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lochnessy said:…Are there any devices or equipment for this?…
What’s wrong with your hands or forearms and a stopwatch?
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SaraLee said:I’d love to get my hands on some, but as a hobbyist I haven’t been able to find a small batch source. If you know of one I’d be forever in your debt! How about sodium phytate?I’m in the same position ;( .Anyway, phytate is worse. Small amounts of EDTA should work even if there’s some incompatibility.HEC should work.@Abdullah Slow cool down or hold heat for some time (one of the few exceptions where this might pay off for small batches).This is not just due to the (co-)emulsifiers within the oil phase which need to get to the interface but also because coco glucoside is a polymeric and therefore a ‘slow’ emulsifier which needs some time to ‘get in place’ and if the oil has already hardened too much it can’t incorporate into the interface.
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Solagum AX already contains xanthan .Cellulose serves other purposes. I guess improved skin feel, film formation, and probably additional stability. Feel free to tweak the formulation.
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Imagine you were to park your car outside in a hailstorm and get dents all over it… does the dilated metal sheets tighten back when you apply a cream or lotion or do the dents simply fill up to be less visible?
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That amount of wax results in solid oil droplets. Depending on the speed of cool-down, the emulsifiers won’t have a chance to organise properly.These solid oil particles will have a positive charge which plays well with honeyquat but not so much with xanthan gum. I suspect that these two polymers will ‘clog’ around the oil particles and allow them to flocculate.Personally, I would use a non-ionic polymer instead of xanthan.Natrasil can go into the oil phase and might help making these less high melting and more flexible.As mentioned above, PEG-100 stearate should also help and you might even use it instead of coco glucoside.
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Neither. Propanediol is just a protic solvent and MSM a solid which, due its close relation to DMSO, is often called a penetration enhancer without reliable citation. MSM may have other effects on skin penetration as you can read HERE (not saying that this is a reliable source nor that the results may be extrapolated).
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Maybe… the undispersed 0.4% whould have to stick somewhere and, depending on manufacturing process, can either be lost (to the wall of the water vessel) of get incorporated properly into the product during emulsification.The problem with Naticide is that nobody except Synerga know what it actually is. Could be a very good or very poor preservative, could be a scam and a pile of lies, could be adulterated with whatever preservatives like several other ‘natural’ preservatives on the market… As long as I don’t see proper, independent data and know what’s really inside, I wouldn’t trust such a ‘preservative’, let alone use it as sole preservative. You can’t really adjust production processes when you don’t know what you’re using.Which bacteria did they find? Maybe add a second preservative which is strong against these .
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Grooming and brushing is what helps and so does a good diet. Else, most breeds shed their underwool twice a year and only superglue will stop that for a while. Maybe just advertise it as ‘best for poodles and Yorkies’ (these breeds don’t shed by nature LoL ).For the sake of the dogs, just make a mild shampoo which doesn’t burn in the eyes, contains some conditioning ingredients, doesn’t contain too much perfume, and add some anti-hairloss claim ingredients.
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You could replace it with bentonite. I known, it’s nearly the same just less pure (and not from Vanderbilt) but the INCI is bentonite and hence free of any scary chemical words .What does it do in there (0.2% isn’t much)? Bentonite/Veegum can serve several purposes in different formulations and, depending on its job here, different alternatives may be considered. In this case, I don’t think it’s about viscosity but more about emulsion stabilisation. Hence, a thickening/co-emulsifying agent such as hydrophobically modified polymers or water soluble polymeric emulsifiers should work at low levels (mind, they usually have scary INCIs too!). More natural alternatives which require a bit higher inclusion rates might be gum Arabic, LaraCare A200, or BergaMuls ET 1 (as might be the proposition of @ariepfadli ).
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If I’m not mistaken, Lush products have very short shelf lives (and I have the impression that they don’t properly test them).
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You have to get rid of oxygen and keep it out of the bottle till the last drop. Reducing/reacting all that enters is an option but certainly not the best one. For that, you might want to try sodium metabisulfite or sodium dithionite. However, you’d best keep ascorbic acid and the airless/darg packaging but also de-gas all liquids (best flush with nitrogen and work/fill under reduced pressure).The only thing you might drop is either phytate or gluconate. Maybe adding Redoxol S3 (in addition to all the other antioxidants, not instead of them!) might help somewhat if you have to go with normal packaging…
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Coumarin is a potential allergen (and hepatotoxic in larger quantities) and hence has to be listed in the LOI if it’s present above a certain level (EU: 0.001 in leave-on and 0.01 in rise-off products). The origin of coumarin is usually the added perfume (in which coumarin may be present as part of an EO or because it has been added in pure form). The level therefore is commonly very low (EU regulates oral intake from food at 0.1 mg per kg body weight per day) but it’s present in many perfumes and transdermal assimilation might push daily uptake above the allowed amount.