[Pharma]

Depends on the powder: Type of powder, quality of powder, particle size and size distribution, porosity, surface modifications, type of powders used in the blend, ratio of included powders in said blend, just to mention some factors affecting the amount which can be suspended and whether or not a gelling/thickening agent should/could be incorporated.

You could also use dry water and mix that with a powder .

[Pharma]

I don’t know if it works (I don’t even know if my brain still works, ‘t was a looong day) but what if you included triethyl citrate in your formulation? It’s supposed to degrade to citric acid and thereby lower skin pH, faster where bacteria grow but it’s also metabolised in living skin cells. Might be a trick to make ‘high’ pH lactic acid work better. Again, just brainstorming here!

[Pharma]

Maybe it’s a fragrance additive, there’s no real regulation, or they just don’t care?

The only ‘hole’ I can think of right now doesn’t start with an L but a P… :smiley:

[Pharma]

Hydrolysed proteins are often hydrolysed by cooking proteins in acid or alkaline solutions. As a rule of thumbs: The smell thereof is reminiscent of bouillon and they tend to be brownish in colour. “Quality” hydrolysed proteins are obtained by enzymatic digestion and therefore smell less/not and are less/not coloured.

Keratin is a protein, not a hydrolysed protein and hence prone to denaturation… or am I missing something? Denaturation means loss of secondary, ternary, and (if present) quaternary structure without necessarily breaking primary structure (i.e. hydrolysing it by breaking peptide bonds aka cutting the strand into pieces). Denaturation often results in protein precipitation, they clump like milk going sour. This effect may even be observed with partially hydrolysed proteins (polypeptides) but is less likely with highly hydrolysed ones (peptides and oligopeptides). Heat may have other detrimental effects on peptides such as degradation/oxidation of sulfur containing amino acids (cystine, cysteine, and methionine) which are frequent in keratin. Not that this is likely to bother any cosmetics company or cosmetics user, let alone affect efficacy (because efficacy is unlikely to be due to added keratin)… LoL

[Pharma]

With “I don’t know Siligel” I mean I never worked with it and don’t know how too much gums feel like .

[Pharma]

Laurannecarly said:

Unfortunately when including Lactic acid I can’t go below pH 3.5…

Why? Doesn’t make any sense to me… Is lactic acid getting dangerous below 3.5?

Salicylic acid won’t be a good replacement because, unlike lactic acid, free salicylic acid is not water soluble.

From what I’ve read, at a pH between 4.4 and 5.6, self-degradation of ascorbic acid is slowest. Anything you add which increases solubility (some solvents and free lactic acid might likely be considered one) increases speed of degradation. Other publications indicate that pH doesn’t matter regarding for example lipid peroxidation by AA degradation products (obviously not by AA itself which prevents it).

Furthermore: anaerobic degradation is favoured by low pH whereas aerobic degradation depends on AA deprotonation (which happens in alkaline conditions and requires oxygen).

Bottom line is: You shouldn’t lower pH and it certainly doesn’t mean you should do so by adding another acid but if really necessary, just use less sodium hydroxide. Quite the opposite, you should increase pH to +/- 5 and avoid oxygen. Because iron and copper have a tremendous effect on degradation speed especially at the most stable pH range, it also means you should avoid trace metals in your ingredients (most likely source in your case is almond oil and technical grade sodium hydroxide) and use a good chelate appropriate for the formulation’s pH.

[Pharma]

Your oil phase is 10% oils, 3% cetyl palmitate, 2% cetylalcohol, 0.5% Amisol containing phospholipids & sterols, and Siligel containing lecithin… This is 1/3 ‘hard fats’ and to me, this sounds like possible trouble (doesn’t need to be but could be).

Me, I’d mix the first 4 ingredients to see how this ‘pure’ oil phase is like on skin. I expect it to show that what you call ‘rolling/balling’.

I don’t know Siligel but reading a formulation guideline I’d have to concur what @ngarayeva001 said. Maybe not because of the lecithin but the large amount of polymers.

[Pharma]

Resveratrol is a phenolic compound and behaves similar to tocopherol but it has a certain water solubility which tocopherol is lacking. Resveratrol is also better regarding protecting lipids from peroxidation and is slightly superior in several antioxidant tests.

Its solubility in water and oil allows it to shuttle between ascorbic acid (water phase) and lipids (oil phase). As an educated guess, this would mean that resveratrol pushes degradation pathway towards the aerobic side. Maybe, there is no CO2 formation (if it is CO2 and not H2 -> hold a burning match to a larger bubble ) because aerobic degradation doesn’t go all the way down to the step of CO2 formation?

Unfortunately, this amphiphilic character also allows it to interact with certain emulsifiers which might explain the observed stability issues.

BTW colour reactions such as seen with ascorbic acid degradation are not correlated with actual % of degradation and won’t tell you whether it’s aerobic, anaerobic, or mixed type degradation.

Do you have means of running experiments like simple chemistry tests such as determining peroxide value or ascorbic acid quantification (you’ll need iodide or iodine, respectively, and some other basic chemicals), run a TLC, or even got fancy machines?

[Pharma]

How many % did you use?

[Pharma]

@ngarayeva001 Found another publication:

Citation from: Influence of oil types on the formation and stability of nano-emulsions by D phase  emulsification by Wanping Zhang et al. DOI:10.1080/01932691.2020.1737538

2. Experimental

2.1. Materials

Span 80 (sorbitan monooleate, HLB = 4.3) and Tween 80 (polyoxyethylene sorbitan monooleate, HLB = 15.0) were purchased from Sinopham Chemical Reagent Co.,Ltd. The ratio in weight of Span 80 and Tween 80 used was 3:5 (HLB = 11). The five kind of mineral oils (7#, 10#, 15#, 26#, 32#) and caprylic/capric triglyceride (CCT) were supplied by BASF Corp. Isododecane, isohexadecane and squalane were supplied by INEOS Oligomers. Ethylhexyl palmitate (EHP) and isopropyl myristate (IPM) were obtained from Croda Chemicals. Furthermore, triethylhexanoin (THE) and glycerin were obtained from Lubrizol and Infinitus Co.,Ltd respectively. Deionized water was used to prepare all emulsions.

2.2. Preparation of nano-emulsion by D phaseemulsification

The D phase emulsification process was carried out as fol-lows. At first, 2.0 g of glycerin, 3.0 g of Span 80 and 5.0 g of Tween 80 were mixed and the yielded mixture called the D phase. The mixed HLB value of the Span 80 and Tween 80 in this ratio was 11. Then 20 g of liquid oil was added drop-wise with stirring at specific temperature into the D phase and then an oil-in-surfactant clear gel formed which called O/D phase. The stirring procedure lasted for 30 minutes to produce a fine O/D phase which was very important to the formation of the nano-emulsions. For O/W nano-emulsion preparation, gradual addition of water (to 100 g) to the O/D phase was carried out with stirring. The stirring speed of the whole preparation process was 700 rpm.

[Pharma]

As said, lipoic acid is unlikely to help with stability of AA due to it being dissolved in the oil phase at low pH and assuming that it’s not going to turn into dihydrolipoic acid it won’t have any protective effect on the oil phase either.

I would also only add more fancy ingredients after you’ve figured out a stable prototype.

Once there, I’d dissolve lipoic acid in the oil phase.

I certainly wouldn’t add flaxseed oil. Given your stability issues, I’d even consider switching almond oil for a more stable one. Either MCT, jojoba or ‘synthetic’ ester oils or for a natural somewhat unsaturated fatty acid profile a seed/nut oil like meadowfoam, crambe, or macadamia.

Since ester oils like coco caprylate are of low viscosity, highly spreading and ‘drying’, a combination with a refined seed butter could give a closer ‘sensorial’ match to almond oil whilst being more stable than a seed/nut oil. At least, check analysis protocols for your oil; only use batches with a low peroxide value.

Reason why I mention oil stability is that tocopherol may act as pro-oxidant at higher %. Literature data are not conclusive but 1% as antioxidant seems a lot and that for maybe not too much of an effect on skin. Degrading tocopherol also drives degradation of ascorbic acid which regenerates tocopherol until there is nothing left for toco to degrade. Thereby formed dehydroascorbic acid may even speed up oxidation processes… Lipid peroxidation & degradation can also release CO2, not just self-degradation of AA. Hence, it’s unknown what exactly degrades to an unknown gas apart from AA being somehow involved. Therefore, it seems wise to do anything to increase stability of the whole formulation even if you’re just after AA.

[Pharma]

As long as you don’t know how much of what exactly you’ve lost, you can’t be sure whether or not your product is adequately preserved.

[Pharma]

Tocopherol and rosemary extract come to mind. Ascorbyl palmitate is not entirely natural but made from ‘naturals’ and would be a great partner for aforementioned phenolic antioxidants.

[Pharma]

Benzoate plus an acid/sequestrant is not a broad spectrum preservative.

[Pharma]

Could you work under reduced pressure (vacuum)?

[Pharma]

Laurannecarly said:

…Will get back to you with an update. Thanks!

You’re welcome.

Looking forward to hear how it goes.

[Pharma]

You probably added it too fast.

[Pharma]

Back from a walk with the doggies and some time of thinking…

There are a few flaws in my above post:

- MEA would be your worst choice. It reacts colourful with ascorbic acid degradation products.

- DMEA shouldn’t be a problem because it is a tertiary amine. Unfortunately, there are a few exceptions which do degrade for example in the presence of ascorbic acid such as MES and MOPS which do so via not so healthy amine oxides. Like PCA shouldn’t pose a problem but yet it does, such incompatibilities aren’t predictable applying schoolbook chemistry laws. Whether or not DMEA is suitable or not, I do not know. From experience with MOPS, degradation is visible within hours to days. DMEA is known to scavenge hydroxyl radicals from ascorbic acid degradation (for example in presence of EDTA chelated iron)… Best would be some means to determine DMEA degradation in case you decide to go with that.

- Lipoic acid won’t work because it’s oil soluble.

[Pharma]

What’s in your serum? It might not be MAP or not MAP alone causing the effect.

[Pharma]

Yea, today I stumbled over a product containing 40% ultrafragmented hyaluronic acid… in the small prints it reads 40% of a 10 ‰ concentrate.

[Pharma]

Laurannecarly said:

…There is one study where the anaerobic oxidation of AA is observed and this is exactly what we’ve been experiencing: https://www.tandfonline.com/doi/full/10.1080/10942912.2013.805770…

As long as you don’t determine degradation products, there is no telling which way degradation runs. The anaerobic pathway releases CO2 in an early step. Aerobic degradation runs via dehydroacetic acid, a reaction which can be reverted using the right antioxidants, and only at a latter point releases CO2. And both pathways release H2. Bottom line: same amount of gas, just that anaerobic is a bit faster.

Unfortunately, it’s fairly difficult to get water content low enough to considerably slow things down without switching to an anhydrous formulation.

Can’t remember whether or not you told us the pH of your emulsion. According to your link, increasing pH towards neutral might help to slow degradation reactions down. Downside is, efficacy of your product might go down.

Assuming you couldn’t stop degradation but are just looking for a cover-up:

Avoiding PCA might help because it’s likely contributing to colour formation (publication). PCA might even speed up degradation by creating a ‘sink condition’ (removing reaction products and thereby turning an equilibrium into a one way street).

Removing CO2 could be achieved by using an appropriate buffer system. I don’t know if your lactate buffer works well for carbonate. Only looking at pKa, I’d go with citric acid. An amine instead of NaOH might hypothetically also work better. MEA (monoethanolamine) as a volatile base bears the ability of catching CO2 also in gas form; it’s used industrially for this purpose. However, the very low pH greatly reduces volatility of MEA, not to speak of MEA probably not being the best cosmetic ingredient. DMEA on the other hand… it’s less reactive and less volatile but a great cosmeceutical. It stinks less too but it still reeks of dead fish (you’d have to use free base DMEA and not the less smelly and more often used bitartrate salt).

In theory, simply increasing pH would already help to turn carbonic acid into bicarbonate. Sadly, one problem with CO2 is that it doesn’t readily convert to carbonic acid just by being dissolved in water. Our body uses carboanhydratase enzymes to speed up this process. Using ionic liquids or deep eutectic solvents instead of water would be another approach… but that’s likely too sciency for a cosmetic product.

Removing H2 could be attempted by adding an oxidised compound. Off the top of my head, suitable cosmetic ingredients might be alpha-lipoic acid and glutathione (cystine isn’t commonly used), or certain synthetic dyes (which turn colourless upon reduction ). These withstand direct reduction by ascorbic acid but should react with H2. However, this is just a guess… it works nicely with H2 in situ generated by mixing zinc powder with diluted acetic acid. The advantage would be that the created reduced compounds are strong antioxidants and will regenerate ascorbic acid from dehydroascorbic acid.

[Pharma]

Could you be more specific?

[Pharma]

ngarayeva001 said:

But yeah “who wants to put anti-freeze on their face”… 1,2 Propanediol. Same thing but hey, it’s made from corn.

Antifreeze is traditionally ethylene glycol but PG is also used as a less effective but safer alternative.

Commercial propylene glycol aka 1,2-propanediol is a 100% fully synthetic petrochemical and not from corn. 1,3-propanediol comes as a version obtained through fermentation of corn but it costs more.

[Pharma]

Melcas said:

…phenoxyethanol is a great one but unfortunately I’ve used it in the past and have had adverse reactions to it.

…if 1,2 Hexanediol would be a broad spectrum or if I should mix it with other things. Any suggestions help thank you!

I wouldn’t solely rely on 1,2-hexanediol. If Symrise and co. don’t, you probably shouldn’t either .

You could however use it in combination with a reduced amount of phenoxyethanol or use a similar phenol (phenethyl alcohol as an example) instead and/or an organic acid (anisic and/or levulinic acid). By choice or necessity, a booster (e.g. glyceryl caprylate or ethylhexylglycerin) and certainly a chelate (EDTA or phytate) can or should be added as well.

This is just to give you an idea! Cocktails are, especially with alternative preservatives, better than fighting just on one front.

Consumers are stupid… the more ridiculous a rant, the easier they gulp it down. Besides, you can never satisfy them. Last week, our masks were too expensive (wholesale was expensive for us too), today’s shipment was okay $-wise but the masks were green and she wanted blue. F*ç#”!

[Pharma]

ngarayeva001 said:

…I am not saying you cannot make other emulsifiers work but you will waste liters of materials until you establish % at which that emulsifier solubilises completely…

Not to mention the time you might waste because some emulsifiers sediment/separate after weeks of storage and seemingly good stability…

I was really happy and astonished how well my first oil cleanser turned out until a few weeks have passed and one of the emulsifiers started to ‘fall out’. It’s still working but looks like it has mould on the bottom.