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So work in this context is measured by reduction of TEWL I assume.

Any studies on it with metrics on efficacy? E.g. what do vegetable oils do compared to mineral oils? What about hydrolyzed proteins? And good “natural” alternatives to dimethicone? Not using Zinc in this case.

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“Moved” the discussion to Soap Making forums, some good responses there if you’re interested! http://www.soapmakingforum.com/showthread.php?t=43507

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http://www.creative-developments.co.uk/papers/Trends%20in%20Emulsifiers.pdf some good info

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So I neutralized my water based formula w/solids incl zinc, then added about 5% (yes..) carbomer to make a thin gel, when used with a treatment pump bottle the resulting lotion actually has a really nice consistency with no additional thickeners, but using that much carbomer can leave some dried carbomer powder on the skin. So I’m going to try xantham and sclerotium gum next, others recommended are “Bentone Gel, Veegum, Cellulose types”.

I skimmed through all the links/papers, def good data for optimization, some coated zinc types work with carbomer too it seems. The lubrizol yield paper is particularly good imo.

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Looking at the cursed whole foods list, I see that Glyceryl Stearate is not on it (but glyceryl isostearate is..) nor is cetearyl glucoside, so I guess it’s both ECO and wholefoods friendly. So the Herbiary sells it as “Sugarmulse. Will get some..

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Think i’ll try rose water or cucumber, not a lot of reports on allergic or sensitizing reactions with those! But would be interesting to see some comparative data, also, obviously, depends on amount.

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Bwahaha, sparkling mouthwash! Good tip. 

So I’ve been playing around with Carbomer, doesn’t seem to play too well with solids, I tried it with colloidal sulfur in Acacia gum + zinc oxide, mixing the solids into the water phase, adjusting the pH and adding Carbomer to “freeze” the solids in place quickly, but had to use an obscene amount, 5-10 grams, to create a gel, and this was even with minimal immersion blending (as it shears the polymers). Keep in mind this solution also had 15% isopropyl alcohol.

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How about using borax and beeswax? I’ve heard that combo can work too. Less “chemical” sounding perhaps.. I know..

Otherwise there’s EcoMulse:

Glyceryl Stearate                       55-65%

Cetearyl Alcohol                        20-30%

Sodium Stearoyl Lactylate      10-20%

And NeoDefend: Gluconolactone + Sodium Benzoate (GSB)

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But I’m sure there’s a correlation?

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BTW, where to get Polyhydroxystearic Acid? Also, if you just make the lotion thick enough, then sedimentation won’t be a problem, correct?

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For now this is just an idea, wondering whether such a product would be commercially viable and how large the “label” benefit would be.

So it would have to work in emulsion, unlike Leucidal Liquid. But I guess there are other oil compatible ECOcert ones on the market?

Leucidal LiquidLeucidal Liquid

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That’s great advice, what about taking a large sample of saliva at one point and storing it in the fridge? Lypholizing it? Hehe, joking. I assume it’s best just to take new samples after your rec.

In any case it seems like the best way to do a rough semi-standardized screen, I might play around with some “””natural””” preservatives to see if any are up to snuff. Then do USP 51 on any promising candidates.

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@Microformulation I think you’re missing my point, my point is to do a rough screen BEFORE sending samples for USP 51 testing, if you’re doing a lot of samples e.g. testing different preservatives, sending all of them to USP 51 testing could get cost prohibitive at > $400/sample.

@Tonyh useful link to the common usage test, cheap to at $31 for anaerobic bacteria + fungi, but to really test your product you’d still need some microorganisms to contaminate it with in the first place..

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Thanks @cosmochem , good info about the compatibility issue, any particular particle size you need to suspend ZnO with polyhydroxy stearic acid? Suspending agents are a new field to me, would be curious to read more about them.

I was looking at the Mario Badescu buffering lotion btw: Deionized Water, Isopropyl Alcohol, Sodium Sulfate, Zinc Oxide, Hydrolyzed Serum Protein, Hydrolyzed Yeast Protein, Pyridoxine, Niacinamide, Panthenol, Propylene Glycol, Allantoin, Biotin. 

I wonder what form of Zinc oxide they are using, there is some visible sedimentation on their product images, a “shake before use” product, also curious about whether their sulfur is colloidal or not.

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Normal blenders and immersion blenders seem to work quite well to shear things up without creating too much air, I’ll do some experiments with the boat prop @MakingSkincare but I suspect as you say there’ll be too much pump+air and too little shear.

a simple sheet metal blade like this _____|_____

                                                                                   would probably work decently? Guess you just have to experiment.

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Thanks for the feedback, I agree that USP 51 should be done by pro’s, but sometimes you want to do crude testing before you send your best samples off for expensive $300-$500/sample professional testing which is why you can buy those microbial testing kits with double sided stick for fungal / bact growth.

@The_Microbologist

Great answer! I have done some microbiology in my training as a molecular biologist, and can get access to Class II biosafety cabinets, but would prefer something easier and safer, it doesn’t need to 100% mimic USP 51, but should consistently challenge for bact and fungi at the very least. I mean, what do people use the home testing kits for anyways?

Thanks!

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I have indeed tested a inline speed regulator and it works fine with staff mixers, but not at all with brushed Dremels (just FYI).

People seem to say that you need to limit slicing force*time or you could render the emollient ineffective, but haven’t seen any data on it. I guess I’ll just experiment and see what works, getting some SS sheet metal and a RC boat propeller shaft (which conveniently will clamp in place anything with a hole in it).

Not a big fan of Xanthan btw, make emulsions leave residue for longer.

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That would work, but I was more thinking something about blade geometry.

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Interestingly some use essential oils as preservatives at under 1%, I wonder if there are any that are low on smell, high on antimicrobial/fungal effect? Seems sketchy to me

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Thanks for the warning! Making a spot treatment for myself, if good I might get a contract manufacturer to manufacture it down the line.

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Selling in as in getting your products onto retail or online “shelves” or selling to US and EU customers shipping your products from Australia?

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Interesting, there are commercial anti acne products that use sodium sulfate, so this would be a good source?

http://www.essentialwholesale.com/product/1949/colloidal-sulfur

Thanks for the info!

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Benzoyl Peroxide, makes my work more exciting. 

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Thanks for your excellent replies, my initial thought was to use micronized zinc oxide with a ~200 nm particle size to potentially help against acne, not for SPF purposes: 

http://www.makingcosmetics.com/Zinc-Oxide-micronized-currently-out-of-stock-p195.html 

Adding it after emulsification during cool down under high shear mixing (~5000 rpm staff blender or equivalent).

I basically want to keep particle size as low as possible and avoid sedimentation. I’m not sure whether that is equivalent to a colloidal dispersion? 

Requested a sample of UV Cut ZNO-61, looks good! Any other pre-solubilized products out there?

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0-2000 rpm, $132, ships from CA, but might not be fast enough for robust emulsification? Dremel + rheostat a more flexible tool?

http://www.ebay.com/itm/Electric-overhead-stirrer-mixer-variable-speed-25-W-New-/330401686003?pt=LH_DefaultDomain_0&hash=item4ced79a1f3