[Pharma]

You could also use potassium hydroxide. Some emulsions behave quite differently with different bases, others not so much. Similar to sodium soap usually being solid whilst potassium soap being liquid.

[Pharma]

You could use carbonates as base but they form CO2 once fully reacted. Hence, if you don’t mind a bubbly product and a workspace full of slimy foam…

Depending on the used acid (e.g. acrylate), full reaction is slow and in order to avoid formation of gas, you could add twice the amount needed and end up with one part neutralised acid/polymer, one part sodium bicarbonate, and no bubbles. This means, given you did the maths right, that sodium carbonate is now only 1.5 times cheaper, you might run into difficulties due to an increased amount of dissolved electrolytes, might have to spend more money on preservatives since your product will be pH >8, and, if you’re unlucky or opt for a slightly lower pH than 8, overpressure builds up during storage because of a small excess in acids.

Me, I wouldn’t use it.

[Pharma]

Not that much of a challenge if there’s no water present. Sure, honey is hygroscopic and might absorb water over time. Assuming it’s going to be a honey in oil emulsion, this effect is minor and therefore preservation is more of a ‘better safe than sorry’.

Regarding emulsifiers: Unfortunately, HLB considerations won’t work with pure honey as ‘aqueous’ phase… I guess it all comes down to trial and error.

[Pharma]

What is Ag-P?

[Pharma]

Hydrofluoric acid? How would you get that? And you’re likely to die faster and terribly painful from handling HF (especially if you try to heat a non-hermetically sealed container) than from getting arrested by police . HF is volatile, super toxic, and gets into your body through your skin and your lungs. Oh, and did I mention that you’re very likely to suffer a lot before or rather until you die? Not joking here! Just as a side note: HF is, at least in water, a rather weak acid, evaporates at room temperature, is safest to handle in HF-pyridine or the like, and dissolves glass. All that makes it very unsuitable as an esterification catalyst.

Car batteries (the older ones) contain strong enough sulfuric acid (it’s strongest when they’re charged) for your purpose but you should probably buy fresh battery acid and not use an actual battery since that acid is loaded with lead and hence not very healthy. Though, this didn’t kept me from doing exactly that as a kid . The pharmacy wouldn’t sell it to a 14 year old but the guy at the garage had no issues with giving me some old batteries (one of which exploded nearly into my face when charging it… always be careful and wear gloves and safety goggles!).

As said, I’d try phosphoric acid as a safe alternative.

[Pharma]

???

What type of spectrograms?

You’re unlikely to find anything useful and publicly available other than TLC pics. You’ll find spectroscopic data and a lot more on natural products HERE but it’s going to cost you a few pennies (it’s THE reference work and a must have if you’re doing research with herbal constituents).

Spectroscopic analyses are done on whole plant extracts but more often to identify new constituents or quantify certain constituents (in order to standardise said extract) rather than to confirm identity and these are also seldom published, let alone in a complete work. You’ll have to dig through pubmed and sciencedirect.

The problem is, plants aren’t a defined compound and extracts are different between growing sites, seasons, varieties, soil type etc. etc.

What are you trying to do?

[Pharma]

The ‘pharmacy only’ cosmetics (we call it ‘dermocosmetics’) we sell here are often slightly different to ‘common’ cosmetics insofar that their ingredients are ‘on the safe side’ and hence, they contain less to no perfume, colours, and known allergens but also less to no plant extracts as well as claim ingredients (well, they often contain 1 or 2 plant extracts and a claim ‘drug’, because, you know…). Some even come +/- without preservatives (airless dispensers). They, not necessarily all but many, contain less and more stable ingredients (synthetics over plant oils) but else, they are just cosmetics and often not even the best made ones; if you sell ‘med grade’ then it’s probably going to be okay if rheology and sensory profile aren’t top notch. It’s just another angle to catch fish in a different corner of the pond.

[Pharma]

Menthol will melt and dissolve in all the other oils and essential oils, just crush the crystals first and then give it some time and mixing.

Menthol is simply a crystalline essential oil and doesn’t require any emulsifier.

[Pharma]

It’s probably mostly cheap lactose and LAA in there…

I like betaine, allantoin is nice too, and trehalose has some interesting features was well (although not necessarily in a skincare product). Panthenol is too sticky for my taste, ribose is an overly hyped sugar, hydrolysed collagen might be useful, and 1,2-hexanediol can be a handy preservation additive though I like pentanediol more (because it’s based on renewable resources).

Is your blend worth buying? Not for me, I prefer pure compounds over blends of unknown ratios. Selling pure stuff to boost your beloved cream up to another level ain’t new and demand for such things is increasing. What counts most here is a good marketing strategy .

[Pharma]

Some pharmacies here around have an FT-IR spectrometer and might be willing to test the product’s identity for you.

Another version are physico-chemical tests as for example elaborated in pharmacopoeias. I’m a nerd, I admit but I’m not a filthy rich nerd and rather lazy tonight. This said, I don’t have a pharmacopoeia at home and hence can’t look it up for you but you could ask your local pharmacy for a printout of niacinamide.

It’s rather unlikely that they sent you vitamin D because it’s quite expensive.

[Pharma]

Some ingredients require heating, others emulsify at room temp.

Shear is usually required although there are exceptions which do self-emulsify upon dilution (and slight mixing) or heating.

[Pharma]

BTW I wouldn’t use an emulsifier (e.g. polysorbate 80) or your product will emulsify in water and wash off easily.

[Pharma]

Some aluminium tubes (at least all those we use in the pharmacy) are covered by a fine layer of polymers which renders them fairly resistant to most cosmetic ingredients. Pure aluminium will dissolve in acidic pH resulting for example in aluminium lactate.

[Pharma]

Your product has no hair growth character… unless you’re adding things like minoxidil, there won’t be any no matter how you tweak your formula.

The quantity of paraffin is fair as long as you’re satisfied with your product. There is no reference % for this kind of cosmetic ingredients.

[Pharma]

The TEWL curve might cap at 90% and 1% petrolatum could also show the same reduction or petrolatum simply isn’t an optimal ingredient in the used vehicle?

[Pharma]

Check out Ajinomoto, they are the ones who invented these surfactants (or at least managed to produce it large scale).

[Pharma]

They can get cloudy at lower temps . Bring them to 25-30°C and if they become clear again, they’re okay. Polysorbates are very stable: Tween 60 is visually stable for years but might get cloudy at higher temps when getting old whilst polysorbate 80 starts smelling rancid before you see any degradation. I found some long forgotten bottles in our cellar which were over 20 years old and they only showed minor visual signs of ageing. Smell wasn’t okay but still far from rancid.

[Pharma]

Wouldn’t it be fairly easy to reverse engineer a cream simply by using chromatography (HPTLC/HPLC/GC) and mass spectroscopy? Depending on composition (cause polymers and extracts are not so easy going) and given that you have concentration curves of reference compounds, the bulk could be copied within an hour.

[Pharma]

Abbass_1 said:

My Question is: just like we have pH control for preservatives and anionic/cationic surfactants, do we have the same for TDS?

I still don’t really get it. TDS is everything dissolved in water which doesn’t evaporate upon boiling. IMHO TDS can’t be compared to pH.

Where I live, water quality reports of our tap water are available online .

Anyway, you can control some side-effects resulting from certain dissolved salts such as heavy metals (most of all iron) by adding a chelate.

The effect of divalent cations (usually calcium) on emulsion stability can not be quenched/prevented by suitable means.

Buy a small RO unit or at least a cation exchange resin cartridge as used to produce soft water by exchanging calcium/magnesium against sodium.

Demineralised water (the one for car coolers or pressing irons) isn’t that expensive.

[Pharma]

Meemcha said:

…May I trouble you for a brief explanation of that 3:1 limit as recommended concentration of Polysorbate 20 is usually up to 10%. What am I missing here?

That’s just a rule of thumbs. In order to be transparent or at least translucent, emulsion droplets have to be in the form of small micelles rather than droplets. Empty polysorbate 20 micelles contain only about 80 surfactant molecules. Essential oil molecules need to be dissolved between the lipophilic tails rather than forming a core as is the case with ‘standard’ emulsions. Else, the droplets become too large and the solution turns milky. That’s why the ratio of EO to surfactant is a lot small than the ratio of oil phase to emulsifier in a common cream/lotion.

Furthermore, larger droplets tend to cream whilst small micelles are small enough to be subject to brownian motion which counteracts/supersedes gravity.

[Pharma]

Use distilled or demineralised water .

[Pharma]

Perry said:

…
Micellar water is a marketing term, not a scientific term.
You can call whatever you want micellar water. The only question is
whether your consumers believe it.

Not quite; sure, micellar water is mostly used as marketing term but it
is also a scientific one. Every surfactant in water, at a given minimum
concentration (critical micelle concentration aka CMC), builds micelles.
This is one of three (?) feature which makes a surfactant a surfactant
(notably, most non-polymeric emulsifiers have the same features and also
form micelles but these have simply lower HLB values).

The
water in your lavatory or your bathtub is, scientifically speaking,
micellar water once you added enough soap, shampoo or washing agent to
form the first bubbles.

[Pharma]

teyodora said:

Opinions on Methylchloroisothiazolinone in rinse off products?

It’s omnipresent in many household chemicals such as dish-washing liquids, floor cleaners, room sprays, or paint. Like many chemicals with such widespread use, there’s a fair amount of people developing allergic reactions to it. Also, I don’t like it being an organochlorine compound (not nice to mother nature) with mediocre biodegradation (there are far worse compounds). At least MCI has great water solubility and therefore advantage over several other synthetic chemicals used to suit our modern needs.

[Pharma]

No TEA. REAL cold cream does neither contain an emulsifier nor emulsifying wax. Some add it or use small quantities of sodium lauryl- or laurethsulfate to help the emulsifying process and increase emulsion stability but the trick of cold creams is that they are stabilised only by wax which increases the oil phase’s melting point so that the ’emulsion’ is more like a semi-solid lipid sponge filled with water. Once applied on skin, the card house collapses, liberating water and causes a slight cooling effect. Modern cold creams have nothing to do with this kind of old-school cold cream.

[Pharma]

My favourite base formula for cold creams is the one from Dermatologische Magistralrezepturen der Schweiz:

Beeswax                         8

Hydrated peanut oil      17

Refined peanut oil      ~50

Castor oil                       5

Water                          ~20

Also contains antioxidants and sometimes a small amount of sodium dodecylsulfate. The peanut oil - hydrogenated peanut oil part can easily be swapped in part of fully with liquid paraffin - petroleum jelly whereas the emulsifier may be omitted (better ‘cooling’ effect i.e. emulsion inversion) or replaced with something else for increased stability or a nicer feel.

I also like to include some cetyl palmitate and cetyl alcohol like it’s done in many traditional cold cream formulas.

These cold creams are actually very versatile and efficient for such simple composition. Greater for cold windy weather and calloused hand/feet, less for aesthetic cosmetics such as day creams.