[Pharma]

@Abdullah Usually, smaller micelles means higher stability (but uniformity is as important). Smaller particles result in a larger surface area and that also means that more emulsifier molecules are located within the interphase. If, in a particular case, one really has to use more emulsifier is a different story.

[Pharma]

I’ve tried out LaraCare A200… and couldn’t see/feel anything happening. It requires quite high inclusion rates and then results in a weird skin feel. Arabinogalactans (galactan chains with arabinose branches) are the main constituent for example of gum arabic. The larch tree derived galactoarabinan is part of the tree’s hemicellulose, doesn’t resemble any gum, and doesn’t affect viscosity. That it reduces micelle size and the film forming property were reasons why I’ve tried it out. Alas, I don’t know if it does so or not (I don’t have access neither to a Zetasizer nor a skin humidity sensor ;( ). Feel and chemistry wise, I do have my doubts that it can reduce TEWL… I would have guessed the opposite. In my case, it did hamper the initial emulsification process and I needed to add it afterwards (which is totally stupid cause then, it can’t reduce micelle size as effectively). Maybe it was just my formulations and it works great with others… I think it has a similar effect on emulsions than bentonite but with a less visible viscosity increase and requires quite high inclusion rates.

You may market galactoarabinans also as prebiotics (that they are prebiotics only for the intestinal flora doesn’t need to appear in the marketing blurb).

@MarkBroussard Thanks for the AHA tip. At least I know what to do with the remaining sample.

[Pharma]

@chemicalmatt Nope, I have not. I have HEC 5000 (Natrosol 250 M), Lotioncrafter’s HPC (which they don’t seem to offer any longer… so I have no specs ;( ) and MC (wallpaper paste LoL) sitting around on my shelves. I might give HPC a try, thanks for the tip!

The reason I haven’t tried HEC/HPC yet are, under others, the fact that they are ethoxylated/propoxylated, pharmaceutical CMC and HEC gels feel just awful and, maybe most importantly, I’ve totally forgot that I have them. But yes, they’re closer than polyacrylates to what I’m looking for.

However, I would guess that cetyl HEC might be suited best… any advice would be highly appreciated!

[Pharma]

She proposes PGPR… urks… great in food technology but for cosmetics, there are certainly better options out there (maybe not cheaper ones, though).

And you might still face the issue of matching optical densities in order to obtain a transparent emulsion (= go with a glycerin/polyol based extract).

[Pharma]

Polyglyceryl esters can also be paired with sucrose esters. I like the skin feel and handling of both but the combo even more (that’s just my personal preference, no ‘real’ reason behind it).

True about the rheology stabilisers: I haven’t managed to make any low viscosity product even close to stable without them. However, I also haven’t been able to find one which matches my expectations and self-inflicted requirements ;( . The closest I found are acrylates/C10-30 alkyl acrylate crosspolymers… However, the one I’ve got is Carbopol Ultrez 21, not the best choice for sprayable lotions (but, theoretically, better suited for a high non-water part in the aqueous phase). Maybe Pemulen TR-2 would be better??? Apart from that, I work with high inclusion rates of electrolytes and that’s a really bad precondition for polyacrylates. I’ve also tried a xanthan-guar gum combo (cause more ‘natural’ and better electrolyte tolerant) but the consistency is slimy whilst the cold process glyceryl esters I’m currently playing with don’t result in satisfactory lamellar structures. Therefore, stability is still far from useful even with both strategies together (and it certainly wouldn’t spray… which, in my case, it doesn’t has to). I’m still looking for my perfect rheology modifier.

[Pharma]

Madonherbs said:

…I understand the HBL scale but can’t work out how to use it in a practical way…

I suppose you mean HLB… That system does work for a very narrow range of formulations mostly based on PEG-emulsifies.

I do, from a hypothetical and traditional standpoint, understand the system but, like most people and most applications, can’t work out how to use it in a practical way either. That’s simply because that system is useless… it’s just there because it’s been around for so long and because there’s only one other system around which does work (HLD-NAC)… Alas, that one is difficult to work with and for most ingredients, the values are unknown/unpublished.

[Pharma]

The new Bepanthol Dema line by Bayer only uses glycerol, 1,2-hexanediol, and citric acid… no airless, no antioxidant, no proper chelate, no nothing… I contacted them (mainly because they claim ‘free from preservatives’) and they answered with the usual blabla everything is great blabla (and our layers say that it’s not a misleading claim blabla).

So, if the claim is not misleading according to the EU, then their whole line is not preserved (glycerol and hexanediol would be included at low levels for hydration claims only). WTF!

Maybe I should put some ‘compost flora’ in one of their bottles and sue them when it grows? *har-har*

[Pharma]

Regarding upscaling: Imagine you had each a sample of 100 ml and of 1’000 ml in a small and a large beaker, each as wide as high: from a rudimentary calculation base, you’d need about ten times as many turns with the same tool to get the same mixing. Using the same large beaker, once brim full and once only filled to 1/10, then you’d need the same numbers of ‘swirls’. In the first experiment, you’d need 10 times longer and hence have a 10 times higher chance to introduce small air bubbles and also get 10 times more evaporation of the D5. In the second case, process time is identical but the surface area vs. its volume in the small sample is bigger and hence, the small sample is more likely to get air bubbles trapped inside and loose ingredients due to evaporation.

This is only to show you how difficult and unpredictable upscaling can be. It also tells you that turbidity might be caused by very small air bubbles and/or as a consequence of ingredients (namely D5) evaporating.

Who’s the manufacturer of the amino acid? Knowing more about the structure might be helpful. I can’t find anything useful with ‘AC KERAIN AMINO ACIDS SIL ‘ or similar wordings…

[Pharma]

One explanation could be an optical ‘illusion’.

If you take an apple, it’s not transparent, but if you cut fine enough slices, they become seemingly transparent. This happens quite easily with liquids which appear to be more transparent (less cloudy, less coloured) in smaller beakers than they do in larger ones. If you judge transparency, make sure to always take the same quantity with the same path lenghts for the light to travel through.

The other thing I wonder about: Why does keratin lead to an opaque serum and why did you decide to use C12-15 alkyl benzoate to remedy that? From a purely physical/chemical point of view, this doesn’t look obvious to me.

[Pharma]

@kajalthakur What you’re looking for is called a book… 😉

[Pharma]

What about Cola Moist 200? Recently found this at a DIY site but didn’t got to try it yet.

BTW I’m not suggesting this as a solution but I’m actually hijacking your thread 😉 .

[Pharma]

Use high refractory index protic solvens or suspend micronised extracts or extract impregnated silica.

[Pharma]

Why would one add PFAS to a fragrance oil? Also, sulfates (in anhydrous products) and parabens aren’t common ingredients either… WTH! That’s why such claims are no longer allowed in the EU.

[Pharma]

Graillotion said:

are any of these a synonym….and if not…any of them equally delicious?

Diisopropyl Adipate

Dioctyl Adipate

Di-PPG-3 Myristyl Ether Adipate

Diisobutyl Adipate

Diethyl Adipate

No synonyms.

Dioctyl adipate might also refer to diethylhexyl adipate… anyway, these options have two shorter alcohol parts sticking out of the two ends of adipic acid. They’re mostly used as solvents or fabric softener. The closest might be Di-PPG-3 Myristyl Ether Adipate but the PPG will have some effect… ask someone who knows the two for the difference.

[Pharma]

@chemicalmatt Thanks for the feedback!

Nope, it’s not a Pickering emulsion. These work with particles, not soluble things.

I would like to have a polymer ‘barrier’ around the oil phase (a bit like in a Pickering emulsion) but with it being anchored in the oil phase. By preference a linear entity spanning from one oil ‘droplet’ to the next. This can increase viscosity of low viscosity emulsions without increasing the water phase’s viscosity or rather independently of the viscosity of the water phase which obviously increases to some degree. Alternatively, it forms a more stable and less HLB or HLD dependent steric hindrance when each end sticks in the same ‘droplet’ forming a loop with the hydrophilic middle part. A cross-linked polymer or comb like hydrophobically grafted linear polymer is the plan B (these certainly have additional pros).

A workaround might be the combination of an anionic polymer with a cationic emulsifier but the effective ratio between the two is very narrow and it’s a highly electrolyte sensitive and pH dependent system.

[Pharma]

geepee said:

Hi Guys,

I am trying to formulate a W/O emulsion and wanted to get some more ideas on how the formulation process differs from O/W.

So far I have:

• W/O needs an electrolyte in the water (disperse) phase It usually helps
• W/O needs low HLB emulsifiers Not necessarily, only for ‘traditional’ emulsions
• W/O cannot have gums/rheology modifiers such as xanthan as water needs to disperse Sure they can and they help with stability
• W/O generally needs polar oils (MCT, castor oil etc) and generally low content of other plant oils No, not ‘need’ but polar oils (e.g. synthetic ester oils) help. Using hydrocarbons may require some tweaking (lower HLB, more salt…)
• Add water phase slowly to oil phase Usually yes
• W/O can have a higher water content when using special emulsifiers but it it mainly higher in oil % That’s the same believe as with o/w. Doesn’t need to but can.

I have a few questions:

• When should I emulsify?  Should i start emulsifying when adding the water phase like O/W when both are at 75C?  Or simply mix when adding water and then homogenise/emulsify when cooler (if so what temp)? Depends on the type of emulsion.
• O/W you can add a small amount of low HLB emulsifier to stop creaming - can i do the opposite with a W/O and add a small amount of high HLB emulsifier to allow higher HLB oils to be added and still be balanced?  Or do i need to stick with low HLB emulsifiers only? No, blending is in theory fine. However, o/w emulsions are more tolerant and there’s totally other tricks needed to avoid problem X (because the phases are inversed).
• Can a W/O product have a higher HLB than 6 or must be below 6? If it does, does this technically mean it is O/W? It can have, thinking about HIPE gels, and no, HLB values don’t mean anything. They often don’t even apply… I stopped using that system, it gives me more headaches than good results.

If there’s anything I am missing, please let me know as i am having some trouble with W/O.

See within text

[Pharma]

Not sure if explaining which function it needs to perform would actually help… because the function is on a molecular level (the visible/measurable results from that, such as increased viscosity, aren’t my goal but are merely logical consequences).

I’m working with quite high levels of electrolytes and hence, most things I use should be salt tolerant to a degree where one might call it even ‘salt ignorant’.

So, what it needs to do is stick one hydrophobic part A into one oil droplet and the other end into another oil droplet and bridge it at distance B. It should help to increase stability of low surface tension emulsions such as microemulsions and near-microemulsions or, respective, emulsions close to HLD 0. This would likely also increase viscosity as a welcome result but for that outcome, I could use other gelling agents as well. It might further help to stabilise non-crystalline lamellar networks and o/w HIPE gels (depending on chain length B ). But that’s purely speculative but something I would, one day, like to try out.

[Pharma]

There’s a good and bief overview on LNGs on UL Prospector.

[Pharma]

@Graillotion Polyglyceryl-6 distearate and PG-3 beeswaxate are the main
emulsifiers in Emulium mellifera, that pot sitting unused on your shelf you sent me… just saying
.

[Pharma]

Art of GREEN! ROFLMAO! How suitable!

For those not lauging, it means that you’re not a nerd who knows that P. aeruginosa produces a beautifully disgusting green pigment (cooler even under black light) which gives pus it’s yellow-green colour.

[Pharma]

@chemicalmatt Accoring to some other manufacturers, certain types of silicones work as o/w emulsifiers or at least co-emulsifiers… I found the following:

ABIL
Care XL 80 or ABIL
Care 85

Silquat
versions, a cationic emulsion

PEGylated dimethicones with at least 10 PEG units such as THIS
and similar dimethicone
elastomers

PEG/PPG methicones or dimethicones with something in the range of 18
or more PEGs and derivatives
thereof, by preference more PEGs than PPGs (see ABIL Care)

And there’s also that one polyglyceryl
modified dimethicone

Any insights regarding these (you’ll have to follow the links… it’s a copy-paste out of an email)?

[Pharma]

Reversed phase means w/o type emulsion.

Hexagonal is a type of lyotropic liquid crystal phase. These phases depend on the system (type of aqueous phase, type of oil phase and type of emulsifier phase but also their relative proportions).

Bottom line: There is no definite answer to your question. You may obtain your wish with many different emulsifiers but the haptics may then not suite your needs. On the other hand, you could use the ‘best’ emulsifier and terribly mess up your aim. You can’t predict/calculate it and have to try and… well… you’d also have to have real expensive equipment to determine whether or not the outcome is what you envisage.

[Pharma]

toketsu said:

…
The fact that your serum is still clear might not mean LAA is still non-oxidized. I heard (but I don’t claim it and would like to know if it is true) that brown color in serum is a reaction of LAA oxidation with aminoacids (the same way as fake tan reacts in skin). So if you have plain mix of LAA and Water you won’t see a color? Also, I’ve seen that there are several steps of degradation, so some products of degradation might not have a color? 
…

The first oxidation step results in a nearly colourless compound which can be reduced back to LAA. Higher amounts should be noticeable as a slight ochre hue. Further reaction steps lead to autopolymerisation and, as you mentioned, also to polymerisation with amino acids and other molecules. These polymers are usually red to brown. Yellow colour can either be shorter polymers or, such as the case with ferulic acid, are the oxidation product of ferulic acid (which is inrensely yellow, if I’m not mistaken).

[Pharma]

toketsu said:

LAA quickly degrades in presence of electrolytes (which is Sodium, right?), although I am not sure if it applies in waterless solutions.

Do you have any source for that claim? Sodium and lactate are both electrolytes… Anyway, it does degrade faster in presence of certain metal cations (mostly ‘redox active’ heavy metals).

[Pharma]

@Graillotion If you had asked that Q 30 years ago, I’d probably mentioned thiomersal. Many countries have, fortunately and for several reasons, discontinued/banned the use of mercury and organomercury compounds in general or at least for most applications at the end of last century/millenium.

Several other compounds (mostly heavy metals) show a similar broad-toxicity antimicrobial effect (often alongside toxicity towards all other forms of life, too) and most have as well been discontinued or banned (for this and other reasons). The list includes antimony, arsenic, bismuth (fairly safe but quite weak, only bacteriostatic, and hence still in use for example in the US as Pepto-Bismol), lead, nickel, thallium, tin… heavy metals still in use are for example copper, silver, and zinc. Some organoborons also belong to this list of compounds showing an ‘oligodynamic effect’. Alas, the ones in use are less effective (assuming one uses safe levels) and often come with diverse drawbacks (and they don’t cover the whole microbial spectrum either).

Other broad spectrum ‘toxins’ often won’t cover bacteria as well as yeast/fungi such as geneticin or glufosinate but will cover humans… a lose-lose situation :'( .

Other options include chemically reactive ingredients such as strong oxidisers such as hydrogen peroxide and iodine… which nicely cover everything including spores and a good part of cosmetic ingredients and human skin as well. Another dead-end.

Octenidine would cover a broad range of bacteria and yeasts (not clear how broad the effect is there). Efficacy against moulds is not known to me. All you had to do would be a combo with a broad-spectrum fungicide (if you sell outside of EU where either isn’t in the ‘approved preservatives annex’).