[Pharma]

Lecithin comes in a variety of grades, from fairly cheap to really expensive.

Effective regarding what? You’re comparing apples with oranges.

[Pharma]

Your boosters are pure marketing, they will not do anything useful. Sorry for popping your dream bubble ;( .

Bottom line is: Create a booster your customers like (because TV hypnosis etc. :blush: ) and which is easily added to whatever shelf-picked product you desire.

[Pharma]

Several issues I see:

- Caprylhydroxamic acid (the main active, utterly non-natural ingredient in Spectrastat G2 Natural) is a potent complexing agent for zinc and copper and mainly acts through complexing said trace elements within microbes. Adding that much herbal extracts (green tea) will introduce considerable amounts of many different metal salts which will bind and inactivate caprylhydroxamate. Phytic acid is not strong enough to counteract this (no commercial chelate is though green tea polyphenols might partially help…) and hence, you are highly likely to have killed a good portion if not all of your main preservative. The little bit GMCY in your blend will not hold.

- Green tea contains different types of polyphenols. Many of which have a catechol unit or in other words are great chelates for iron and other metals (often stronger than phytic acid), oxidise readily (can’t be reduced by bakuchiol, the only antioxidant you use), and polymerise further to form dark pigments. What you need is a strong antioxidant and an airless, light-proof dispenser. At least add ascorbic acid or, less natural but more efficient, metabisulfite, dithionite, or similar. This will help more than trying to find an adequate chelate. BTW an antioxidant will turn iron into its +2 form which is a lot less of an issue regarding pro-oxidant effects.

- Lecithin plus high loads of herbal extracts are tough to preserve. I don’t think that discolouration is due to microbial growth rather than oxidation but I’d still be very wary about your preservative strategy even if you were to switch out caprylhydroxamic acid (something you should really consider doing).

[Pharma]

If you want a replacement for TEA, you could try dimethylethanolamine (DMEA) or arginine.

Sorbitol is less tacky but IMHO less hydrating and more expensive. Maybe try a mixture of the two too?

[Pharma]

No, it’s worse!

Oatmeal is also a great food and energy source for horses, Scots, darkling beetles, fruit flies, slime mould… Oatmeal is usually whole grain and generally a very rich and valuable source for nutrients and that makes it one of the ‘healthiest’ cereals for many different life-forms. Most microbes would agree too.

Sorry for the bad news.

[Pharma]

I don’t see too much (or at least close enough) similarities between LGN (often called alpha phase) and skin but I get why cosmetic industries might extrapolate from one to the other.

HERE‘s a quick reading about the subject. And, as mentioned by @Graillotion, you’ll find a fair bit of posts here on CST.

Certain lamellar structures will be similar to the mortar and cement between corneocytes and thereby positively support healing but that heavily depends on the used emulsifiers and hence is only true for a very few products.

[Pharma]

Polyglyceryl fatty acid esters are ‘green’ and from renewable resources aka ‘natural’ though they require at least one synthetic steps (the rest can be done with enzymes) which is polymerisation of glycerol (= heating, with or without catalysts). In the EU, certain types (mostly the lower HLB types) are approved food additives (E 475). Also glyceryl stearate citrate and fatty acid (di-)lactylates are edible. All these are quite versatile ‘natural’ and ‘green’ alternatives to PEG derivatives. They may not be as ‘good’ as their ‘synthetic’ counterparts but close enough IMHO. GSC and lactylates are, depending on pH at least partially non-ionic or behave as such at higher electrolyte concentrations. HERE‘s an example of an edible cream.

Certain polymeric emulsifiers are also edible such as LaraCare A200 (larch gum like Larex is a food additive and GRAS). Xyliance (cetearyl wheat straw glycosides, cetearyl alcohol) is also likely to be without concern (it’s sucroglycerides E474 and fatty alcohols which are both edible).

Fatty acid glucosides (not to be confused with fatty acid glycosides) are probably edible but, you know, who wants to be the first to try?

[Pharma]

Polyglyceryl esters, lysolecithin and lecithin .The most widely used polyglyceryl ester in foodstuff is PGPR though that’s a w/o emulsifier.

[Pharma]

No, hygroscopy doesn’t equal moisturising effect but it helps a lot. Like worms don’t catch fish but hooks do. And yet, I wouldn’t go out fishing without worms :smiley: .

Hygroscopy is like bait, it attracts water whereas moisturising is the hook which binds water to your skin. Sure, most hygroscopic substances are actually doing both.

[Pharma]

Did you try adding/increasing fatty alcohols?

[Pharma]

The very definition of a foaming agent is based on reduced surface tension and by definition, anything which reduces surface tension is a surfactant. Even if you use foaming proteins or plant extracts from organic farming or whatever, the active principles therein are automatically surfactants.

[Pharma]

At a pH above 10, some mould (mostly on the surface) and alkaliphile bacteria can grow. I’m not familiar whether or not such alkaliphiles are even present in everyday life and/or are common cosmetic spoilage germs. If you want/need preservation at all, you might consider adding a preservative which is active against fungi, chemically stable, and slightly volatile (headspace preservation). I’m thinking of phenylpropanol or its combo with caprylyl glycol and/or pentylene glycol or hexanediol. With luck, the glycols might increase the products haptic profile too by reduce cracking/whitening as well as soothing/moisturising skin.

[Pharma]

If I remember correctly, GMCY (glyceryl caprylate) can be used at lower rates (= lowest recommended dosage) in conjunction with other preservatives if it’s meant more as a booster than a preservative. Glyceryl undecylenate is likely only working within its recommended range and I would be hesitant to reduce it too much just because you add a second/third preservative.

It also depends on things like: Are you running a stress test? Do you have issues with initial bioload or with contamination during usage? Do you know which microbes will/still grow in the simple preservation product? Do you get partial but broad spectrum preservation and only fail to reduce CFU count below your target value? Of all kinds of microbes or only certain varieties? Where do microbes grow first in/on your product?

Depending on such questions, lower amounts of aldehyde releasers may suffice to bring your blend to full speed. If you add a third preservative because of its ‘selectivity’ against a microbe insensitive to your initial blend, then the ‘full’ amount should be added. Using benzyl alcohol as a ternary might work at lower levels if its only purpose is as a headspace preservative in case of an otherwise well preserved product. That’s just to give you a few examples and ideas, not a 1:1 recommendation.

Knowing which preservative works how (if we even have a rough idea about its mode of action) and against which microbes helps to decide whether a mixture of two is redundant, partially overlapping, complementary, additive, or even synergistic (a thing maybe not very common with preservatives). And this in turn will determine if a lower % might work or most certainly won’t.

If you can’t answer those questions and run proper tests, then the use of
lower amounts, especially if you lower all used preservatives, is a
gable.

[Pharma]

If used at, say, 5%, they will contribute to a lower water activity. Together with other dissolved stuff, it might bring it so far down that microbes will start to starve which allows other preservation hurdles to work bether .

3) Correct. Linear C8 chains, no matter whether it’s caprylyl glycol, caprylic acid, glycerol monocaprylate, or similar, are often antimicrobial and perform better than C6 or C10 analogues. This is thought to have something to do with water-lipid distribution causing microbial membrane disturbances.

BTW there are many more hexanediols of which the 1,2-, 2,3-, and 3,4- are glycols in the proper sense. However, INCI doesn’t know proper sense :smiley: . 3,5-hexanediol is a misnomer and would be the same as 2,4-hexanediol. Cosmetics usually uses 1,2-hexylene glycol whilst the 1,6-isomer is a common synthetic intermediate. Having both hydroxy-groups at one end of the carbon chain turns all these glycols into co-emulsifiers which allows for membrane interactions whereas hydroxy-moieties distributed somewhere greatly reduce this antimicrobial effect. Moisturising wise, this is probably less of an effect though too long carbon chains reduce water solubility and hygroscopy = the longer the chains, the less moisturising the molecule will be.

There’s a thread from this year about the sensory and humectancy profile of several such ingredients somewhere hidden on this board .

[Pharma]

10% propanediol would keep many bacteria at bay, 15% would be the minimum against many yeast and moulds including common spoilage microbes, 20% is a good hurdle against all pathogenic bacteria and most moulds/yeast, and 40% is enough to keep also xerophilic moulds and osmophilic yeast at bay. The few microbes still able to grow in there are very rare and would require about 50% propanediol.

Mind, this is only for propanediol and propylene glycol. Other substances have different % requirements.

[Pharma]

It’s polymerised silicic acid aka precipitated silica. At first, it forms a layer of ‘glass’ on your skin but then, due to movements, that layer cracks into said powder. You can not prevent it from happening, it’s an inherent property of silicates. There have been investigations and some patented inventions which claim stabilised silica. A: This, were it working, would not form the tightening film and B: My trials didn’t work out. I did recook and modify about a dozen and none were stable for more than a few days at the concentration I wanted.

I’ve never tried anything regarding stabilising the film (my trials were for other uses such as hydroponics and fun experiments with deep eutectic solvents because one key ingredient therein is claimed to stabilise silicate solutions). My imagination here would be to add a gelling agent or film-forming polymer to ‘glue’ that glass layer together and imparting enough flexibility to the film to keep it from cracking and have it stick to skin better.

[Pharma]

Oh god, don’t remind me of that thread! My vivid imagination got the better of me back then :blush:

True, silicates are tricky to formulate and predict, I know as much from hydroponics.

[Pharma]

Bottles make poor targets, that’s why you have troubles shooting ’em :smiley: .

Seriously, you could get pharmaceutical ones which are more consistent but still remain natural products or simply buy pure essential oils and add those (maybe dilute with preserved water).

I’ve seen several hydrosols for sale which aren’t preserved… I think that this is criminal.

Hydrosols sound nice but they are just an upcycled side-product. It’s nice for reducing waste but if you want some consistency, go with the pure essential oils, a perfume, pure extract (these will show batch-to-batch variability too), or whatever.

[Pharma]

It would be better to test pure ingredients rather than a cream. Lipids and emulsifiers can interfere with the assay.

At least use positive and negative controls = a cream without added antioxidants/herbal extracts and one where you add a fair amount of a known working antioxidant. This would also give you the answer to your Q.

[Pharma]

EiraSh said:

…Euxyl K712? How effective is it, combined with trisodium EDTA?…

As I already mentioned, this is a standard preservative system for pharmaceutical preparations (water based solutions and oral preparations) and is usually combined with a chelate such as EDTA. It’s fairly effective for ‘edibles’ but I wouldn’t rely on it for room-temp storage over more than a few months without proper testing. It’s a more or less well tolerated minimal requirement combo which isn’t suitable for ad hoc (= DIY) cosmetics and requires thorough testing and the addition of further hurdles if used in a new formulation. BTW several pharmaceutical preparations using this have to be kept at 4°C and/or have a shelf life of a few weeks if no other ‘preservatives’ (e.g. ethanol, polyols) are added. Also, dispenser systems or tubes should be used instead of pots.

[Pharma]

Wait a sec… water plus sodium and magnesium aluminium silicate without an added acid = alkaline brew (pH >11) = hydrolysis of Argireline and ethylhexylglycerin, likely degradation of phenoxyethanol, and probable degradation of Yellow 5.

Not that Argireline would do anything useful in that product in the first place and I’m also not complaining about loss of preservatives in a product which doesn’t need preservation, it’s rather the absence of any logic behind such a mixture and who the heck had the weird idea to put waterglass on his/her face? Maybe try to add a polymer to hold the film together for a longer period of time and retard/reduce cracking once dried?

[Pharma]

The ones with the lower surface tension . Surface tension depends not just on the properties of the surfactant (such as CMC) but also on the solution in which you use it, additional ingredients, the interface to be affected (in this case solution/surface and not solution/air as usually measured) which inherently depends on the material/structure of the surface to be wetted.

Depending on those factors, a surface charge can have an effect but a charged surfactant isn’t inherently better than a nonionic one.

Monomeric surfactants have smaller MW than polymeric ones.

[Pharma]

Free water is water not ‘occupied’ by dissolving stuff (especially electrolytes) such as salts or amino acids but also polyols, sugars etc.

In order to bring something into solution, said substance needs to interact more with the solvent (water) than with its own kind. Like a flock of men ‘dissolving’ a flock of women. Both flocks hold hands with their own kind and dissolving means changing your hand-holding partner with the opposite sex. Once all the women have ‘dissolved’ in the male crowd, those men not holding hands with a woman are ‘free’ and may therefore cause trouble . It’s the same with water molecules not busy holding hands with solutes; these are accessible for example to nourish microbes.

Knocking free water down to a self-preserved level isn’t easy in an emulsion! Usually, free water is just reduces enough to put microbes on a diet, not starve them to death, so they will be more susceptible to preservatives and have less energy to deal with other hurdles set in their way.

It’s like preparing a field for a new crop. You have to get rid of the weeds when you can’t (or shouldn’t) use herbicides. Plucking them by hand helps but it’s not enough. Not fertilising will slow their growth but only that. Not watering will also help (okay, YOU never water anyway) but due to rain, it’s not enough by itself. You can also put up shades or plant trees to reduce sunlight or let chicken or goats graze the land. The list goes on and you might know better than I do what else there is. The trick, in gardening as well as cosmetics, is to use all possible options at once because together they will (hopefully) succeed. Else, you resolve to the use of a herbicide/preservative which in this case will work at a way lower amount than without all the additional hurdles.

[Pharma]

Lidocain HCl is poorly penetrating skin and that’s why the free base is usually used for topical applications (except for wounds and on mucosa).

Solubility of lidocaine HCl is very good, there shouldn’t be any grains forming unless you have a very small water phase, have incompatibilities, or it’s something else which causes the issue.

Mind, neutral pH will result in partial deprotonation of licodain HCl resulting in poorly soluble free base (which is often applied as suspension or else requires solubilisers, solvents, or eutectics).

[Pharma]

Your make a shampoo, right?

Shampoo is a quite concentrated solution of emulsifiers. Why do you want to add another one? Or are you looking for a shampoo formulation recommendation (in which case you should rename your post)?