[Pharma]

IMHO it’s just fancy overpriced fruit juice.

Read THIS thread which is likely covering what you’re asking.

[Pharma]

With magnesium stearate you could likely reduce the amount of candelilla wax. Basically, the two do the same; increase viscosity of the outer oil phase which is a good thing.

Gelling the inner water phase may not considerably increase stability but will affect haptics during and after application. If you like it, sure, try it out. I can’t see any drawbacks or serious concerns with a gel in oil emulsion (except that the emulsification process can be difficult with a too viscous water phase).

[Pharma]

Perry said:

…

But if you restrict yourself to only molecules that exist in nature then an olefin sulfonate would not in any stretch of the imagination be natural.

From an academic chemistry/biology/pharmaceutical point of view, natural is indeed ‘what living organisms can create’. Olefine sulfonate might be natural derived (from renewable feedstock) or petroleum based but it’s not natural.

Along the same line of thoughts: What exists is real, what we don’t know yet is the mystery which drives the researcher to do its best to uncover it (there’s no debate going on wheter the undiscovered is supernatural or the believe in inexistant stuff). For some fields, natural is from nature and includes everything not man made… Even the scientists have no clear definition of ‘natural’… However, the ones working with organic molecules mostly stick to the natural molecules/products can be made by living organisms (even if sold as synthetic stuff afterwards) or they’re synthetic (or fictional/hypothetical).

[Pharma]

I’m completely with @chemicalmatt here.

However, some scientific publications (not by P&G :smiley: ) indicate the same increase in stability. The issue is that the ones I’ve read didn’t use C18 stuff or in a way where it can’t be used… Anyway, it seems as if, at least in some formulations, fatty alcohols wouldn’t align with emulsifiers in a way which is usually depicted. They seem to be slightly offset towards the oil phase and hence, it might well be that the C16:C18 blend performs better even if in a C18 dominated formulation (which remains to be demonstrated). Could it be calculated or predicted? Not that I know of. Maybe in very simple mixtures using COSMO-RS?

[Pharma]

Fatty alcohols have always tourbled scientists… What are they? Where are they? What do they do? To which phase do they belong? And so on…

Me, I tend to count them neither as part of the wate nor the oil phase. We believe to know that one part is very close to the interphase (where the emulsifiers are supposed to be) and possibly part of it whilst the bulk remains in the oil phase… unless in lamellar structures wherein they may be part of the lamellae or form, with a part of the emulsifier, their own alpha-gel, lamellar liquid crystal phase possibly alongside another type of emulsion formed by the rest of the emulsifiers. So, it depends on the type of lyotropic liquid crystals and these are mostly governed by the used emulsifiers. The effect of fatty alcohols is differently in micelles and hexagonal phases than in lamellar structures or in bicontinuous cubic phases… and it’s different in ‘normal’ systems (o/w emulsions) than in inverse systems (w/o emulsions).

Furthermore, fatty alcohols serve as lipophilic linker. They lenghten the ‘reach’ of the fatty parts of the emulsifiers which increases the emulsifiers oil holding capacity.

Ester waxes such as MM and cetyl palmitate are clearly part of the oil phase and just slightly change the apparent HLB/HLD of emulsifiers. They also gel the oil phase (-> high melting point) and may serve as oil binders (increasing miscibility of unlike oils such as triglycerides and hydrocarbons).

This can explain why emulsion A shows an opposite behaviour than emulsion B when swaping a fatty alcohol for an ester wax.

[Pharma]

You’re welcome 🙂

[Pharma]

Some thoughts:

- Blueberry and other seed oils are often derived by different means from the remaining pulp after juice pressing.

- Oils can be obtained by pressing, solvent extraction, or CO extraction. Each extracts non-oil constituents to a different degree.

- Blueberry is not equal to blueberry… The European species Vaccinium myrtillus has smaller, more colourful (blue also on the inside!), and more aromatic fruits than for example the American V. corymbosum and hybrids thereof which make up the bulk of commercial varieties.

-> The blue and tasty one doesn’t need to be fake.

[Pharma]

Given that you don’t eat GDL, bioavailability isn’t a term which applies.

See, you could have 100% ‘bioavailability’ (skin penetration) without any effect or you can have zero availability but a full effect on the dead uppermost keratinocyte layer. Depends also on your definition of ‘effect’… cause PHAs can have a set of different effects, some biological/pharmacological, others chemical/physical.

If you did a silly short-circuit calculation you would assume that 50% bioavailability is achieved at 50% non-deprotonation which would correspond to the pKa value of gluconic acid (which is BTW 3.86). Using the same assumption, a pH of 4.86 would result in only 10% ‘activity’ and a pH of 5.86 1%. Because life is never simple, this is just a oversimplification which is highly likely not going to tell you anything beyond an estimation of skin tolerability at a given concentration. As usualy with cosmetics: You’ll have to try because current maths just doesn’t suffice to predict such complex systems.

[Pharma]

Theoretically, the final acid value can be calculated from the acid values of the used triglyceride oils/butters and their respective amounts.

However, the apparent acid value of an emulsion depends on the pH. You’d have to set the pH to very acidic prior to extraction of free fatty acids followed by titration thereof. It might be faster if you had some fancy equipment such as RP-HPLC at hand…

Theoretically, you could do a reverse titration (saponification with excess base and titrate back with an acid) with the emulsion if you had the value of the fresh sample to compare with an older/rancid one (of the same batch). Depends a bit on the ingredients, though.

It’s not used to evaluate ageing of emulsions and might not be your best choice given the presence of water and antioxidants (hydrolysis without rancidity). Acid values are only an indicator for old oils or oils going rancid due to some correlation but they don’t give any direct indication of rancidity.

A better value regarding rancidity is the peroxide value. In practical terms, several different values are usually used to gauge oils and fats.

[Pharma]

The issue is that too often people think ‘more is better’… What do you do? You add more (at least of the cheap ingredients) and make sure it’s not going to backfire (with hydroxyacids, this means increasing pH).

Do you intend on using it for yourself or for sales? If only for yourself: go low (% wise), go slow and see how your skin takes it and how well it can handle low pH. Go from there, play with lowering pH or increasing %.

[Pharma]

Diabetes comes with a doubling in risk for PAD and that one is associated with hair loss. Combine this with microangiopathy and neuropathy and you’ve got yourself into some trouble… however, I don’t think that hairloss on your calves is the one symptom you’re going to focus on. BTW shampoo certainly doesn’t help. @Pattsi HILARIOUS!

[Pharma]

Copper complexes often have a strong colour. As @Perry mentioned, very little suffices for a blue colour. However, I doubt that copper peptide is absorbing light good enough to give a deep blue colour at 0.001% but probalby more of a lighter blue one… I may be completely wrong with that assumption 😉 .

@MattTheChemist: I thought it’s not much but THAT little? Sure, % doesn’t matter anyway with most peptides because they aren’t active (at least not in a way cosmetic marketing misinterpretes the crappy scientific experiments done with them) or they would be listed as drugs (and more importantly also sold as drugs by big pharma… which they aren’t) in some instances and possible carcinogenics in others. Copper peptide is probalby one of the few exceptions and does actually do things like promote wound healing at a low % level without doing any harm (is it the peptide, the copper, the complex, or a metabolite thereof which actually shows biological activity?).

[Pharma]

PHA are prossibly safer and milder due to their larger molecules and stronger interactions with hydrophilic groups which results in a slower, less efficient, and less deep skin penetration.

Efficacy with all acid peels depends on pH; the lower, the more aggressive. If you have a high degree of salt instead of free acid, your skin can handle way higher amounts. Given that the different acids likely have different modes of action (of which we don’t even know or understand all) makes predictions difficult.

[Pharma]

What keeps urea from decomposing is a proper pH, no matter how you achieve that.

If someone wants to add sodium lactate as humectant and lactic acid to adjust pH; perfectly fine. It’s simply not acting as a buffer. If you @ggpetrov want to use gluconolactone for pH adjustment, that’s fine as well. Just keep in mind to fully hydrolyse it before you adjust pH with it or you’ll end up with a too low pH.

Cosmetic products might change pH due to several reasons other than urea decomposition: Adding something such as TEC to prevent a rise and a good preservative to present a drop in pH (which is mostly caused by microbial growth) is pretty much all we can do beyond proper pH adjustment and avoiding heat to make sure that urea remains as stable as possible. Once it starts degrading, a buffer would at best slow down decomposition but it wouldn’t prevent bloating (1% degradation of a 20% urea cream would roughly translate to 100 vol-%  carbon dioxide formation or a container under enough pressure nobody wants to be near it) and it wouldn’t hamper possible formation of isocyanic acid and cyanate either.

Not buffering away ammonia (the other final degradation product besides carbon dioxide and the reason people want to buffer urea solutions) might probably be considered a benefit because it bears the chance of reeking bad enough to keep those customers not already deterred by bloating from using a possibly unhealthy product 😉 .

[Pharma]

- From what I found out on the internet (I don’t have a scientific explanation why this should be the case, quite the opposite): fatty alcohols are not your best choice in w/o emulsions.

- I have to disagree with @ngarayeva001 :  Unlike o/w emulsions, polar oils are an advantage in w/o emulsions. However, yours aren’t that polar (except for the fatty alcohol) and you wouldn’t gain anything with a hydrocarbon.

- Where I do agree with her: PGPR as sole emulsifier is not enough. Using a combo of it or an entirely different w/o emulsifier system would allow for a slightly higher water phase which goes along with higher viscosity (and hopefully better stability as well).

- w/o emulsions such as yours can fairly easily be broken with excessive (in terms of rpm and time) homogenisation/mixing. Once such an emulsion is broken, it can’t be rescued with more homogenisation. PGPR tends to form double (w/o/w) emulsions which are at your water content and lack of gelling agents rather low viscosity and are, as an educated guess, what happens in your case.

- Candelilla wax can stabilise an unstable or even emulsifier-free w/o emulsion… however, such an emulsion has to have a solid oil phase and is likely to feel quite waxy, hard, even brittle, and will be highly susceptible to mixing. It will break if mixed/homogenised below the oil phase’s ‘melting’ point. Gentle stirring after cool down might be okay (as you observed, it does not tolerate mixing throughout the cooling phase and rapid cooling without mixing is henceforth highly advised). Basically, such an emulsion is the same principle as an old school cold cream (several threads about cold creams are available here on the forum).

[Pharma]

Mixing salicylic acid with betaine in water results in betaine salicylate (at a pH dependent degree).

Also, mixing salicylic acid with sodium citrate (mono-, di-, or tricitrate doesn’t matter) results in sodium salicylate and citric acid (or a corresponding citrate). Again, the degree depends on pH and molar ratio.

In the end, all that matters is pH which turns salicylic acid into a more or less water soluble salt and thereby allows for easier dissolution. In low % aqueous or even anhydrous preparations wherein salicylic acid is soluble, production of salicylate salts results (for most cosmetic ingredients) in a reduced solubility.

[Pharma]

ngarayeva001 said:

Hi all, I am making this mistake apparently. May I please ask why lactate buffer won’t work? 

Because science .

In simple terms: less than 1% of the lactic acid / lactate at the pH urea is most stable at has to do the job. Officially, that’s not buffering (besides the point that, according to ‘good buffering practice’, a ~10 fold excess of buffer with regard to the agent to buffer whould be used). Sure, only a small amount of urea is degrading at a time and the equilibrium between free acid and it’s salts would theoretically provide a certain flux of new available acid for quite a while.

It would work great if decomposition of urea led to a drop in pH… alas, it does the opposite.

A good buffer would have a pKa of +/- 1 (+1 would be better) target pH. The problem is that there aren’t too many options in chemistry of which only very very few are okay in cosmetics.

That’s why triethyl citrate and triacetin are used as alternatives.

[Pharma]

@chemicalmatt Why are people so often promoting lactic acid / sodium lactate as a buffer for urea? It’s no longer buffering at that pH range, let alone preventing the product from a rise in pH which is the main issue with urea.

[Pharma]

chemicalmatt said:

…Now, how to extract that and sell it ???

Don’t. Just use it instead of water! That water… errr… can it even be called water? is dangerously high in sunscreens and hormones. And then claim that your brand is recycling sun creams and helps against hair loss (thanks to the birth control pills) :smiley: !

[Pharma]

I didn’t realise that TEC is/was used as ‘fixative’ so to speak. I can imagine that it does so, given it’s a low volatility solvent.

What it also does (to my knowledge, it’s what it basically does) is to lower pH (@Graillotion it does so also in skin where there is enough water even if it’s applied in anhydrous form) which slows microbial growth and metabolism, hence odour formation.

Aluminium and zirconium salts are not just lowering pH and denaturate microbial proteins, they also clogg sweat glands so there is less food and less humidity for the microbes. Allegedly, this is the reason why it’s so difficult to make good deodorants without aluminium salts.

[Pharma]

Humectancy is independent of any charge or dissociation upon solubilisation.

In case of PCA: PCA is NOT a humectant but PCA salts are.

Is there a structural feature to predict humectancy? No, there is not.

Is there another way to still get some approximation? Yes. A good humectant is usually (but not necessarily) a hygroscopic substance. A very good humectant usually shows deliquescenct, too. Note, being a hygroscopic substance does not automatically mean that it’s also a good humectant! Nobody would consider concentrated sulphuric acid a humectant .

A copy-paste (Valery V Gorbatchuk on ResearchGate) because he put’s it to the point:

…Hydroscopicity has a simple thermodynamic explanation
but encompass too broad range of specific cases. It corresponds to a
process of water transfer from its pure liquid through vapor phase to

(1)
surface of hydrophilic adsorbent (eg. celulose), or the crystalline
phase of hydrate (eg. that of cyclodextrin or inorganic salts), or the
product of chemical hydration, like with CaO.

(2) liquid solution formed as a result of dissolution of a target solid substance in water vapor (eg. CaCl2, sugar, etc., )

(3) solution in liquid substance (eg. TEG).

Respectively, in the case of hydroscopicity, Gibbs energy of this transfer should be large negative. For this,

(1)
Adsorbent should have metal cations, or hydroxylic, or peptide groups
on its surface, or any combination of these. In other words, there
should be both proton-acceptor and proton-donor centers in its pores. A
crystalline receptor should be able to include or coordinate water;

(2)
Solubility of a solid in water should be high; the data can be found in
any handbook with properties of organic and inorganic substances;

(3)
The liquid should have a negative or small positive parameter of
hydrophobicity LogP, where P is a 1-octanol/water partition
coefficient, which can be found in various databases or calculated by
software available online.

This means:

A) On can reason why a substance is hygroscopic but most people couldn’t tell whether a substance shows hygroscopicity or not.

Humectancy is a mixed physiological, physical, and chemical alteration of a complex organ (i.e. skin) induced by a substance applied to it by different means in different carriers under different climatic conditions and so on… All you could guess is that physiologically tolerated substances such as cosmetic ingredients which are hygroscopic (especially if deliquescent as well), very well water soluble or water miscible, and have a low equilibrium relative humidity are likely behaving as humectants.

Sodium chloride is only slightly hygroscopic, not super well water soluble, and it has a high equilibrium relative humidity of ~75% (it’s only abstracting water from air above a rH of >75%).

[Pharma]

The allergenic potential arises from the high degree of unsaturation, particularly the double bond in the 2,3 position with regard to the alcohol. Saturation removes all (in cosmetic quality maybe just most) those double bonds rendering the molecule to a branched fatty alcohol with about the same allergenic potential as those. As an educated guess, hexahydrofarnesol aka hydrogenated farnesol is likely not or only margianlly active against microbes and in the same pot as the emollient ‘iso-esters’ you’ve been researching.

[Pharma]

biofm said:

Theoretically, sodium chloride reacts with sulfuric acid to generate HCl gas. Not sure (or wouldn’t advise) if this chemistry could be used as an antidote for low stomach acid. 

Adding concentrated sulfuric acid to table salt is actually a common way to produce dry HCl in the lab. And no, it does not work in humans because the patient would dissolve before the salt reacted…

Try bitter herbs and spices (as tea or seasoning) best ~20 minutes before eating. This helps to stimulate gastric functions.

Another widespread strategy is betaine hydrochloride.

[Pharma]

Or, as mentioned, use a silicone emulsifier to overcome that ‘polarity’ problem (it’s a lipophilicity problem but for non-chemistst this doesn’t matter).

[Pharma]

Cafe33 said:

I also wonder which ingredient is neutralizing the polymer? 

Isn’t sodium methylhydroxyglycinate fairly alkaline?

Else, the LOI looks a bit like they love hitting a bong or two before work…