[Pharma]

Kimjiwon said:

…sodium hydroxide…kojic acid dipalmitate, 6 copolymer…hydroxyethylcellulose, hydroxypropyl guar, Madecassoside…

Kojic dipalmitate will be degraded by sodium hydroxide to kojic acid sodium salt and sodium palmitate and madecassoside will be split in half resulting in free triterpene and a sugar chain.

What is 6 copolymer?

HEC and hydroxypropyl guar will probably degrade depending on the conditions. They are in theory fairly alkali resistant but still hydrolyse at high pH (pH above 10-12) and high alkali concentration (time and temperature contribute as well, obviously). They also have a lower viscosity at high pH and HEC as an example starts oxidising to some sort of carboxycellulose if pH remains high enough for several days. Furthermore, these gellants take more time to settle at high pH and hence might give an uneven, grainy appearance in a soap.

Maybe just try soap without all this fancy stuff i.e. only oil and sodium hydroxide, probably sodium lactate since this shouldn’t disturb anything, and go from there, adding one by one to tweak your product towards the desired consistency. And, as @Belassi said, don’t use pure coconut oil because that one will not be supple, let alone together with gelling agents. Why the heck are you adding gelling agents anyway?

[Pharma]

You could try hydroxypropyl cellulose, ethyl cellulose, or hydroxyethyl cellulose. They should be soluble in 1,3-propanediol although, quite frankly, I’m not sure if they also thicken, let alone gel, that solvent without any water present.

Or use a high molecular weight PEG.

And there’s another strategy which results in honey-like liquids… unfortunately, these are sticky like honey, often coloured like honey, but alas don’t smells like honey (it’s usually more of a fishy, stall, and/or unpleasant hard to describe smell which you will have to mask with perfume) and require up to ~50% additive depending on the ingredient used for the trick… furthermore, these might be patent protected and if not, then I’m not giving it away for free, not this time.

[Pharma]

@Belassi : Thanks!

No fishy smell or do you mask it?

[Pharma]

Correct, it’s best done before. If you want to measure afterwards, you’d have to break the emulsion and separate the water phase for proper pH measurements. This may be done for example by centrifugation, addition of more oil, or mixing with acetone or isopropanol .

Depending on the product and how you measure pH, it might work directly in the w/o emulsion… well, more or less.

[Pharma]

In order to really reduce fat, you’d have to use something like a decoupler of oxidative phosphorylation in mitochondria such as 2,4-dinitrophenol. This compound has been sold as a weight loss drug some 90 years ago… until a bit too many folks died or rather, until pharmaceutical industry got scared by possible law suits.

Other alternatives I can think of include making more sports, changing to a healthier and lower caloric diet, liposuction, and miracles.

Bottom line is, eat LESS CREAM or at least LESS FATTY CREAM if you want to reduce fat! :smiley:

[Pharma]

@Belassi : That’s really interesting. Are you using it above or below 1%?

@ngarayeva001 : Absolute solubility of EDTA is governed by pH, only speed of solubilisation depends on the used salt or free acid. As long as you have the right pH, you can neatly dissolve any form of EDTA at reasonable amounts (i.e. nearly up to 10% as disodium salt), it might just take a bit longer for the disodium than tetrasodium salt.

[Pharma]

What if only water and glycerine are above 1%? It’s a serum and there’s nothing in there which requires more than 1% (except for water)… if not directly before EDTA, I’d guess the 1% line would be directly after EDTA and before DMAE .

A propos DMAE aka dimethylethanolamine: Not sure if dimethyl MEA is the correct INCI name, it’s at least not correct according to IUPAC. Anyway, this stuff is said to be good and blabla but as a salt on skin, it’s rather unlikely to do anything other than smelling like rotten fish and is likely not used to adjust or buffer pH, so why adding more than claim amounts?

[Pharma]

Ethanol and glycerine preserve mainly by reducing water activity. Hence, % of water counts and ethanol and glycerine show an additive effect.

Let’s assume that 40% glycerol results in full preservation (no microbial growth), 20% would therefore be half the preservation needed. Ethanol, as you say, requires about 20% to stop microbes from growing though you only require the remaining 50% = 10% ethanol.

It’s important to note that this will only result in a no-grow formula, not an ‘everything dies’ product. In order to kill most microbes, you’d have to add at least 40% ethanol and that’s why low % ethanol or glycerine is commonly combined with other preservatives which do kill the little fellows.

[Pharma]

Honestly, I just write some meaningless stuff but add a bunch of hyperbolic words. This lets me look superconductively smart although I have no idea what the heck they mean. :smiley:

[Pharma]

1,4-Benzoquinone

[Pharma]

I don’t know, I just happened to stumble upon these recently (with stumble I mean read, not buy nor try). Seems as if gels obtained therewith are always crystal clear… but that’s just regurgitating what advertisement claims.

[Pharma]

@hugi28 Why 500 Da? Are you referring to the Lipinski rule of five?

This rule applies mainly to drug bioavailability by oral route and not necessarily to skin penetration, let alone effectiveness of cosmetic ingredients which mostly act on the skin and sometimes within the uppermost skin layer.

Heparin as an example penetrates skin although it heavily violates everything in Lipinski’s rule and we don’t really know how or why.

[Pharma]

From what I understand, pickering emulsions are less forgiving to composition changes (= less flexibility such as last-minute adaptations), they are micellar emulsions (= spherical droplets in a continuous phase), have a small particle size with narrow size distribution, and there’s a lot less ’emulsifiers’ to choose from (some are, like @Perry mentioned, nano-sized or else grainy whilst others are expensive such as janus particles). Chitosan on the other hand seems promising at first but alas, requires a high pH for stable pickering emulsions.

The second and third points result in more liquid formulations. I suppose many pickering emulsions will have difficulties handling additional thickening agents.

On the other hand, many modern creams are not micellar emulsions but of a mixed-type containing lamellar phases, ‘liquid crystal’ phases, hexagonal structures etc. with which ‘pickering’ isn’t quite as easy (if at all, let alone that someone understands how that would work). Such mixed emulsions are easier to make, don’t need new equipment, and are more versatile/flexible in most regards.

The trend might be more towards micro- and nanoemulsions using low-cost manufacturing such as cold processing, PIC and D-phase emulsification… but as mentioned, the often liquid consistency of the latter two isn’t what customers want and hence, fancy as PIC and D-phase are, they too struggle getting the attention/prevalence they might deserve. True, they are anything but easy to create.

[Pharma]

No, these are not the same. Arbutin is more hydrophilic than deoxyarbutin and alos more likely to be cleaved to hydroquinone by glucosidase enzymes.

[Pharma]

The effect is not limited to a distinct chemical structure but mostly to a lipophilic, non-ionic structure (of preservative and emulsifier), surfactant-like behaviour, and preservative/emulsifier interactions (which is a result of the former two properties; like attracts like). I cite above citation by @Doreen: “…alcohol, phenyl alcohol, and phenyl ethyl alcohol…/…lipophilic preservatives (e.g. paraben esters)…”.

Most publications as well as most formulations of interest (obviously, pharmaceuticals are studied in more detail than DIY stuff) are based on traditional preservatives of which parabens stand out as particularly lipophilic, non-ionic, and surface-active. Alternative preservatives such as phenethyl alcohol, caprylyl glycol, GMCY, or 1,2-hexanediol etc. show similar lipophilic and surface-active properties which makes them prone to inactivation phenomena. Their yet rather scarce use (in science) is the one reason why there are also only few publications and investigations available showing this inactivation (and any other effect, too).

[Pharma]

Dibutyl ethylhexanoyl glutamide or dibutyl lauroyl glutamide

[Pharma]

It’s likely in there for the only reason it’s commonly used, as chelate to boost preservation (I mean chemical and biological preservation of the product, not preservation of the user :smiley: ).

[Pharma]

EVchem said:

…Hydrogen peroxide is a weak acid, that’s why the solution becomes acidic…

Reason has it that this would mean it becomes alkaline since the acid (H2O2) decomposes .

I don’t have a definite answer but a guess: It might be stabilisers which causes the effect. H2O2 is often stabilised with a small amount phosphoric acid. Once O2 has gassed out, volume goes down and, because it’s lacking a buffer, even that small a change leads to a noticeable drop in pH.

[Pharma]

Glycerol, sorbitol or xylitol may work at proper concentration by reducing water activity. As a rule of thumbs, 40% glycerol should be stable for years, 30% for several months. 20% ethanol is sufficient to stop bacteria from growing although it won’t kill them.

Clover EO is a good antiseptic essential oil which also shows a local anaesthetic effect (taste/smell is unfortunately strong and less pleasant).

Polyphenol-rich extracts (e.g. rathany root, rosemary) may be effective too and help against bleeding and sensitive gums.

[Pharma]

Is it a ready-to-use formula or a concentrate?

A concentrate may be preserved with ethanol.

I think that pH 10 is a bit too harsh for the mouth…

[Pharma]

You’re probably producing cocoyl glycine which is no longer a high HLB anionic sufactant but a low HLB non-ionic one which also lost most of its surfactancy.

At a rough estimate, this starts happening at a pH below ~4.5 (really starting to get problematic below pH ~2.5) -> at a higher pH, you should be fine and it’s likely something else.

[Pharma]

The amount of iodine (iodide, to be precise) is minuscule and won’t disturb as long as you’re not using it in an oxidising formula (e.g. containing hydrogen peroxide or benzoyl peroxide).

Sea salt contains a lot more than just iodide and it’s frequently used and works fine in soaps.

[Pharma]

Depends on what you want to solubilise where .

For what does the abbreviation MPG and DPG stand for?

[Pharma]

Dehydroacetic acid was/is one of the first ‘alternative’ preservatives though it’s a quite old compound which just sounds natural but isn’t and hence is mainly good for ‘free from’ claims. It’s somewhat outdated due to too poor performance compared to toxicity concerns but still got a revival because of that ‘free from’ boom.

Salicylic acid is said to be safer and more efficient than benzoic acid and it’s certainly safer than dehydroacetic acid and has a similar antimicrobial spectrum but also additional effects such as keratinolysis.

Correct, benzoate and sorbate are active at pH 5.5 and lower. Bonzoic acid/benzoate has an activity of ~5% and sorbic acid/sorbate of ~15% at pH 5.5 compared to pH 3. Now that I think about it, salicylic acid is piss poor at pH 5.5… dang, don’t use it! Sorry for writing faster than thinking.

[Pharma]

From what I’ve read, they’re super fancy and very stable because they’re a bit like microencapsulated oil droplets which can neither fuse/coalesce nor undergo Ostwald ripening.