[Pharma]

Using it at low % and in conjunction with antioxidants and a chelate greatly increases shelf life once formulated. The more stable “GLA oils” usually contain a higher % of saturated and monounsaturated fatty acids and/or high amounts of antioxidants.

Polyunsaturated fatty acids are all penetrating skin deep but do so fairly slowly and, since they are very liquid oils usually with C16-20 carbon chains, feel oily/greasy.

Be careful when reading about ‘drying’ oils. This term often refers to oils drying (=polymerising) when used as oil paint or varnish. Cosmetic bloggers and copy-pasters think that they do so on skin too. Sure, an oil with good skin resorption will ultimately feel ‘dry’ and this often coincides with drying oil paints but not always (or rather, many non-drying ones quickly feel dry on skin like macadamia nut oil).

There’s a ton of ingredients and strategies used to correct or mask undesirable effects such as an oily afterfeel.

[Pharma]

The culprit is sodium silicate. There’s a ton of different varieties/qualities, production/synthesis, purity, pH and so on have a tremendous and unpredictable impact on polymerisation (which causes tightening as well as glassy/gritty feeling whilst precipitating and drying). Minor differences in how and with what you make the product likely has a noticeable impact (obviously, this impact is most probably more often negative than positive).

Given that we don’t know too much about silicone/silicate chemistry, let alone how to fine-tune it, paired with often not so pure starting material of varying batch qualities (true for all ingredients but water) and silicates unpredictable/erratic behaviour makes formulating a real gamble.

Sure, we do now know more than back in the ’80 and you might, after thorough literature research and even more trial and error, have a fighting chance (though not an economically viable one) of making something equally good or even better than the original product. That is, until you buy a new batch of sodium silicate, magnesium aluminium silicate or iron oxide and have to start all over again.

Me, I would use a synthetic magnesium aluminium silicate though I don’t know whether or not for example synthetic zeolite would work too… synthetic because of way higher purity (less metal ions which mess up chemistry) and better batch-to-batch consistency. Else, I’d at least use Veegum Ultra or another highly purified version which contains as little bound metal ions as possible.

The other partner in crime is iron oxide because iron ions have a tremendous impact on how and how fast silicates polymerise and precipitate. Replacing this with a different pigment would be worth looking into although I wouldn’t know of any except synthetic fluorophlogopite which, as brown pigments, are covered with iron oxides and aren’t alkali stable either ;( . At least get a high purity iron oxide of known composition and high quality from a reliable source.

Obviously, go with fresh good quality water glass. Maybe produce it yourself from dry sodium silicate of known SiO2:Na2O ratio and play with that ratio: the lower, the more alkaline, more stable and smoother, the higher the less alkaline (called “neutral”) and better drying but more gritty. Using dry silicate requires a pressure cooker to properly getting it into solution. Or, if your filthy rich, use tetraethyl silicate as starting material :smiley: .

[Pharma]

Well, DMAE bitartrate does buffer but 0.5 ml 90% lactic acid will fully react (hypothetically) to DMAE lactate and tartaric acid. The resulting pH will be very low.

You’ve got a different problem, maybe mislabelled lactic acid or a broken pH meter?

[Pharma]

From personal experience, I’d say it takes about 1 hour. That’s how long my wife needs to swipe the floor with Dettol and it works. Well, maybe it works because she stays home and stays safe and doesn’t go disco hopping and shoe shopping like the crazy kids who keep the bug alive and spreading… :smiley:

Unless you test chloroxylenol on SARS-CoV-2 yourself you won’t find the answer you’re looking for, let alone on a cosmetic site.

[Pharma]

That sounds like some PEG-based emulsifiers which show phase inversion above a certain temperature. In theory, Montanovs do not have such a PIT (phase inversion temperature) and hence, are unresponsive to temperature changes.

However, high temperature may prevent lamellar and liquid crystalline structures from forming. PEG-100 stearate is different and hence, you’re probably used to ‘real’ emulsions meaning small oil droplets formed in water like pea in a soup. What you have now at hand is more like lasagne or puff pastry. Unlike ‘pea soup’ emulsions which get finer and more stable the harder/faster/longer you mix, that kind of emulsion requires time and forms rather spontaneously.

If it looks good at room temperature there’s a fair chance that it actually is good. Some stress tests or a few months on a shelf would tell you more.

[Pharma]

Covid-19 is the manifested disease, the responsible virus for said disease is called SARS-CoV-2.

There’s literature stating that chloroxylenol does not kill corona viruses: CLICK

Though it’s main activity is against bacteria, chloroxylenol may inactivate certain viruses at appropriate concentrations within minutes of contact time. It does perform best if used in a 70% ethanol solution… which raises the question whether there’s actually a point in adding it to ethanol if 70% ethanol alone does already a pretty good job against SARS-CoV-2.

[Pharma]

Several cosmetic ingredients come with a certain pH depending on manufacturing methods, due to impurities, or for stability reasons. That pH is often (approximately) listed on the spec sheet or the MSDS.

[Pharma]

Some formulations do change pH after emulsification. For example such which contain pH active ingredients like free fatty acids, salts thereof, or certain ionic emulsifiers (sodium stearoyl lactylate or glyceryl stearate citrate).

In this case, you could centrifuge the final emulsion until it separates and then measure pH in the water phase. Diluting with plain water to achieve easier phase separation can work but may result in false pH values for example in the case of fatty acids and salts thereof (stearate vanishing creams may change pH by several pH units upon dilution!). In that case, some advice adding alcohols (isopropanol or octanol) to break the emulsion; there still is the issue with possible pH fluctuations though less often and less pronounced than observed with water as diluent.

Universal indicator paper may work. Unlike electrodes, these are less shielded by the oil as outer phase and may suck up the inner water phase to give a reading. Depends a bit on your product whether or not paper strips are working (given that you trust indicator paper).

[Pharma]

What’s the pH of your product?

Judging by your description of the smell and your LOI, I would guess that some of the peptides have deteriorated either forming amines (less likely) or reacting with sugars (Maillard reactions). Maillard reactions are most likely because you have peptides and ectoin alongside glucose and a bunch of oligosaccharides and plant extracts in your formulation. In the former case (free amines), dropping pH can help, in the latter case, a large trash can would be the way to go. Many Maillard products are potent aroma chemicals which will be very difficult to mask unless you add a flavour. Alas, this won’t reanimate any potential physiological effect of the degraded ‘actives’.

The main reason for such Maillard reactions is, as @David mentioned, heat or in this case how long you heat.

Either try a cold process or add all the critical ingredients after full cool down.

[Pharma]

Why?

Do you mean how is it possible that someone wastes kojic acid in a chemical peel or why anyone except H. R. Giger’s aliens would make a chemical peel at pH 1.5?

[Pharma]

It’s all a matter of definition and the label you’re trying to comply with… according to mine, polysorbates are not acceptable especially since there are alternatives from natural resources available. Not saying the alternatives were better.

[Pharma]

@ngarayeva001 Even if it would degrade before it evaporates or you’re 6 feet under and don’t need it any longer, degradation will be polymerisation or, in other words, it just gets less volatile and more viscous, like turning into dimethicone… absolutely safe to use even if degraded. It’s not a fat, it can’t go rancid.

[Pharma]

Perry said:

…What evidence is missing from the CIR report?…

The fact that these are extremely widespread and found in up to every second product of everyday life, not just cleaning detergents, paints and insulations but a majority of everything which, at one point during its production, came into contact with water or needed some protection against microbes does contain at least traces.

It’s one of the most efficient and cheapest preservatives for everything and therefore used and produced in insane quantities worldwide and that’s the problem. It’s everywhere whether you want it or not. Obviously, this dramatically increases sensitisation prevalence reaching now, depending on the publication, about 0.1% of the population being allergic to MIT and ~2% to CMIT, respectively.

Furthermore, your report doesn’t mention the ban of MIT/CMIT in leave-on cosmetics in Canada and EU (I didn’t double-check to verify). It also doesn’t mention that since that ban, prevalence of isothiazolinone allergies were declining.

The two links do mention high assimilation of applied product and state a long half-life. That stuff accumulates badly with its t1/2 of about 2 weeks. However, others found different levels of assimilation and excretion times of a few days whilst others failed to measure considerable blood levels… it’s a mess.

HERE an EU report.

[Pharma]

If sedimentation is caused by a progressive viscosity loss, raising pH might be the solution. pH 3 is the lower end of stability for both polymers and I’d guess it’s hydrolysis of these which would be responsible for said viscosity loss.

[Pharma]

Dr_Sara said:

…a set honey (Rapeseed) or a thixotropic honey (Heather) will drip with body heat. It might be solid in the jar but it will not be on your face. 
…

Thanks for the corrections. I didn’t thought it through cause I never used honey on my face… Apropos, rapeseed honey might actually be best as cosmetic ingredient, it tastes awful :blush: .

Never came across a thixotropic honey either… sounds cool!

[Pharma]

Prashy123 said:

…Oxothiazolidinecarboxylic Acid 2%…

Ah, an interesting ingredient! I’m familiar with N-acetyl-thiazolidine-4-carboxylic acid aka N-ATCA or folcisteine, which is used as plant growth regulator.

Like N-acetylcysteine ethyl ester aka NACET and N-ATCA, OTCA is one of the more stable cysteine derivatives and used to increase intracellular glutathione. I’m still a bit sceptical since N-ATCA is not just metabolised to cysteine by mitochondria but also to formaldehyde. OTCA on the other hand is said to decarboxylate spontaneously after a first metabolic activation step by 5-oxoprolinase and has been proposed for infusion solutions (dunno if it’s actually put to real use).

Anyway, quite stable molecules and one of the least in your product to cause any issues . Just focus on the others.

[Pharma]

The higher your %, the stronger degradation and the better visible degradation becomes (-> 1% of 1% is close to nothing, 1% of 20% is clearly visible). You could try to increase pH to 7 (including a buffer might help), add a bit more EDTA (0.2%) and also include a water soluble antioxidant (ferulic acid might work or might not and I don’t know how you manage to dissolve 1% tocopherol…. do the 15% glycerol suffice?) Anyway, phenolics don’t regenerate ascorbic acid -> thiosulfate or metabisulfit would do and also neutralise dissolved oxygen (or flush with nitrogen, at least boil your water to degas it).

Plus, don’t work with metal containing materials (at least pacify these).

[Pharma]

I would prepare minoxidil separately and also apply it separately. A synergism won’t be lost if you’re applying both on a daily bases .

[Pharma]

Not stable, probably even less than retinoic acid and it’s less active. Retinol would be somewhat more stable but it’s also a lot less active too.

[Pharma]

Dr_Sara said:

…
Sadly, I don’t have 20K laying about- unless you mean Euros? 
Can you point me to a good source to read about calculating the Aw?
…

No, not €… and me neither ;( .

Problem is, you’re going to find, as @Microformulation said, some values (mostly defined as salinity) in the food sector and others in horticulture but you’re neither going to find all you need nor anything reliable regarding mixtures (which, indeed, can differ from theoretical blends). Furthermore, you can’t be sure that the published salinity values are really the ones used to calculate water activity. You’d be faster making that product and putting it into a large jar to get the actual measurement. I wouldn’t be astonished if ‘making it’ also involved ordering the ingredients first. Seriously, I’ve tried and gave up! I usually don’t give up unless it’s looking real bad.

[Pharma]

If you could source gamma-glutamyl carboxylase you could achieve a very similar effect to the maleic acid derivatisation but with glutamate residues (which are a tick more prominent in keratin than cysteine) .

Sure enough, you’d still require something to bridge these negative charges and your hair might complex calcium and become less pliable…

A more readily available enzyme which might work but forms covalent (=permanent) bonds between spatially close glutamine and lysine side chains would be transglutaminase. These bonds are very stable but I don’t know whether or not hair contains enough glutamine and lysine residues in close proximity nor if such bonds would result in any benefit. Also, lysine isn’t an abundant amino acid in hair keratin… Maybe try with some scrap hair from the barber shop? Transglutaminase, at least in the USA, can be easily and legally bought… it’s called meat glue :smiley: !

[Pharma]

You can estimate but that gets difficult in mixtures, you can calculate but that gets difficult with less common compounds (which includes most water soluble cosmetic ingredients), and you can use programs to calculate for you (annual licence fees are likely in the 10-20 K).

There is an easy way to do this and all you need is a hygrometer, a tightly sealed container to fit in an open jar of cream and the hygrometer, and a days time . Relative humidity in % divided by 100 = water activity. Simple!

[Pharma]

Fresh and freezer sound promising. Best to aliquot it ASAP upon receipt. Say you were to get 10 g, make 9 x 1 g mini-batches you freeze and 1 you further split into ready to use amounts so you’ll have to freeze-thaw max two times.

Light, apart from oxygen, is your worst enemy and that’s why completely light-tight alu tubes are a good choice. Also working quickly and under dimmed light (no sunlight at all) is advisable.

I once did test tretinoin with FT-IR and you can literally watch it degrade. Not like *ZAPP* and gone, but still a scary degradation speed. If you can afford to, store the cream in the fridge.

There’s a bunch of discussions here, if I’m not mistaken, dealing with how to stabilise a tretinoin cream.

BHT alone won’t suffice, use a combo of antioxidants and radical and oxygen scavengers with different modes of action.

Alternatively, the observed absence of ‘effects’ might be a lack of adverse side-effects because your base is better made than the store bought product :smiley: ?

[Pharma]

Found THIS link, nicely explaining what happens.

Given that it actually works and the bis-aminopropyl glycol washes off, the remaining S-2(-succinyl)cys would impart a permanent negative charge. What happens with that, I’m not sure and a quick search didn’t give anything useful regarding S-2-succinate thioethers and the like. Maybe something similar to maleate isomerase where the process is reversed and releases fumarate and a free thiol (= starting point before applying Olaplex) or oxidation to sulphoxide and sulphone with further breakdown?

Although, maleimido groups are usually used for such Michael additions of thiols (but also amines)… however, these are very reactive compounds and likely not safe enough for skin contact (besides reacting with water). Reaction of maleic acid with thiols at room temperature and unknown (by preference high) pH may be possible but likely quite slow (however, hours to days would still be in the okayish range for consumers) and hence, I speculate that the seen transient effect could simply be an ionic bridging effect of bis-aminopropyl glycol between native negative charges which are, as we know, abundant on hair (else, quaternary ammonium compounds wouldn’t work as conditioners). This effect might be possible to mimic using a longer chained molecule with two positive charges on either side. Like 1,6-hexanediol esterified with two amino acids such as glycine or lysine or adipic acid with two ethanolamines.

On the other hand, chemical modification à la Olaplex could be done using maleic acid (if you could source that) and, lacking a proper linker because you don’t have a nag for kitchen chemistry, a polymeric cationic moiety (there’s a huge array of Polyquats available or go natural with chitosan).

[Pharma]

Most likely reason why: the tretinoin you have has already degraded before you actually could mix it with your cream.

Besides, there is only a small amount of BHT in that cream which is unlikely to suffice to prevent further/full degradation within hours to days in case there still was some activity left.