[Zink]

Thanks @Candance and @Bobzchemist 

You’re probably right, although there as much isododecane in the formula as there is shea and castor seed oil combined. I will try to replace them with triglyceride and perhaps add some microcrystalline wax if necessary. Caprylyl methicone could also work here I imagine.

[Zink]

Thanks Bill, what ballpark % do you think could work?  I noticed I only have Ozokerite Wax, think it could work instead?

[Zink]

Update, Carnuba provided, I’m not thrilled about adding 20 ingredients to a 7 ingredient formula to add a scent, but their scents are really good and only using extracts not essential oils.

Regarding bergamot, thanks for the info, I wouldn’t worry about it in a wash off formula though.

The lactic acid I use is relatively scent free, I think the sclerotium gum adds more scent.

[Zink]

@Bill_Toge for in-vivo and in-vitro both? I’ve seen some DOW whitepapers where SPF double adding certain silicones. I’m actually waiting for samples of certyl dimethicone ATM, seems like a good bet in my formula although I’d be interested in exploring non-silicone options too.

[Zink]

What did you find?

[Zink]

On the flip side some products seem to do better in tube format, particularly thick sunscreen formulas, Neutrogena makes very attractive and extremely visible tube designs using beige contrasted with black/white/bright colors.

But you don’t see as many small brands do sunscreen due to the regulatory requirements and higher up front costs.

Some of the popular Amazon pseudo brands such as OZ Naturals also seem to have success with tubes.

[Zink]

@Bobzchemist yes this is likely part of how they got it, contrasting in-vitro with in-vivo SPF measurements would reveal this.

BTW to what extend do you think large companies measure the effects of each potential UV-booster added? 

@Bill_Toge yep, but typically only up to 2x of %ZnO from what I’ve seen, so more of an SPF optimizer than booster?

[Zink]

@cosmochem thanks, yes I’ve read it can work as a TiO2 coating, yet shouldn’t the pigment be stable without?

Anyways, suspect it’s not actually SPF60, Neutrogena seems to mainly care about putting whatever on their product that will sell best.

[Zink]

They should say Preservative-Free*

* = only using natural ingredients with antimicrobial effects etc.

Or if anhydrous you can explain preservatives aren’t necessary. Ideally also let the customer know what preservative challenge test has been passed.

[Zink]

@Belassi. Yes I mentioned alumina, but I don’t know the specifics of how it’s work for sunscreen.

@Microformulation Personally I prefer to formulate in my Jacuzzi, but I do have 3 CMOs I work with on various projects as well. You would think big brands had professionals to make sure their mineral sunscreens are robust formulations, but turns out 75% of them don’t meet their SPF claims according to consumer report.

Thanks for the calculator, but not really useful for single filter formulas, e.g. entering 10% Zinc Oxide outputs SPF 4.6.

I’m doing systematic testing of different ZnO blends with different emulsification systems and potential UV boosters ATM, commencing outsourced in vitro testing for UV-B and A absorbance later this year post accelerated stability to to then potentially do a 10 panel in vivo test and get a daily moisturizer/sunscreen product on the market likely next year. I aim to announce all this at some point and thank ya’ll for the help.

[Zink]

Thanks for the thorough response, this makes sense.

I’m doing small scale test formulations, so in that case it’d seem a immersion blender could suffice. I do check with my CMOs regarding their equipment.

As for particle size, what intersts me is mainly pigment particle size, either for color cosmetics or sunscreen formulation - would e.g https://www.amazon.com/AmScope-M160C-2L-PB10-E2-Magnification-Illumination-Battery-Powered/product-reviews/B00H7RMHTG/ref=cm_cr_dp_see_all_btm?ie=UTF8&showViewpoints=1&sortBy=recent be of any use for looking at emulsions with ZnO to see how big the particles agglomerates are?

[Zink]

@MakingSkincare in zinc oxide based sunscreens? What kind of boost did you see? All of DOW’s examples are for chemical sunscreen formulations.

@Microformulation For the in vitro (not 10 subject challenge test for FDA) testing we’ll get UV-A and B abs done. Re silicones, I’ve seen claims that the right silicone can improve SPF in mineral sunscreen formulas two-fold, but it’s possible the formula had poor pigment dispersion to begin with. 

@Bobzchemist  thanks, I didn’t find anything too promising with Hallstar although it’s interesting that they recommend Olivem 1000 as an emulsifier in sunscreen applications (used by Epicuren in their excellent formula). Parasol SLX could be interesting if incorporating silicones. Thx.

[Zink]

Looking for nano zinc blends

[Zink]

@Bobzchemist makes sense, what you can do I guess is inform your customers about the science which seems to rather conclusively say that nanoscale zinc oxide particles are fine. Do you btw have any zinc oxide pigment blend recommendations?

[Zink]

@Microformulation I never mentioned “natural”, but thanks for sharing your thoughts What sort of mixing energy are we talking about btw? 
 
I want to make a formula that I will use every day for the rest of my life, so it needs to be extremely gentle, safe and good for the skin (not too good either, some formulas are best cycled) beyond protecting from UV-B and A.

I’ll see if I can sample the Croda one, historically they like to make things overly complicated.

[Zink]

HEC works even with strong peels.

[Zink]

Thanks! Maybe the non-nano demand isn’t as large as I thought, I’m personally fine with nano scale zinc oxide (it’s even FDA approved for used in food), but wondered if there were any off the shelf non-nano non-whitening options on the market, e.g. Grant has a UV-Cut ZNO 61 with a primary particle size of 255 nm that could be best of both worlds for low SPF applications?

But won’t all ZnO be both nano and non-nano? Is it non-nano when > 50% of the ZnO is agglomerated into > 100 nm particles and nano when > 50% of the ZnO is agglomerated into < 100 nm particles?

What I need to know now is which ZnO blends would work best for my use, ideally one in a plant based carrier but  I’m fine with coatings. Grant, Kobo, Umicore, Croda and Antari all make various blends - any experience with them or is it time to order samples?

Then comes the consideration of UV-A protection where large particle size ZnO does a lot better than nano..

[Zink]

Lecithin indeed, egg lecithin is the closest structurally to what you find in the human body I believe.  But maybe there are some other options too

[Zink]

Scent is definitely tricky, I’m waiting to hear what Carrubba suggests. Trying to keep cost pr/unit for scent alone under $0.5.

[Zink]

@Bobzchemist : Interesting, but it technically a synthetic fragrance? which I’m trying to avoid if possible.

@MarkBroussard : Emailed them asking for suggestions/samples

[Zink]

@MarkBroussard 

I’ll try adjusting ph to 3.5 first using sodium lactate. If inadequate I’ll add 1% citric acid first then adjust pH. I’ll also keep the SA propylene glycol solution at 70C for 30 min to ensure adequate solubilizing of SA.

If this doesn’t work I’ll look into trying different solvents, e.g. Methyl Gluceth-20, Hexanediol or possibly Cocamidopropyl Dimethylamine.

[Zink]

jirobrand: Have not made, just theorizing at the moment. I don’t have much experience with beeswax, but I do have some with lecithin + polysorbate 20 emulsification. I’m 100% with you on the natural/synthetic dichotomy, the most important thing is that the formula is good for the skin so the formula will likely have some good synthetics. 72% hydrous lanolin just says: water, anhydrous lanolin on the label. It needs to be a one part system.

Belassi: Actually you DO want egg yolk lecithin on your skin see: 2013 Liposomes for Topical Use A Physico-Chemical Comparison of Vesicles Prepared from Egg or Soy Lecithin. But there are no suitable suppliers of liquid egg lecithin in the us.
Emulium-mellifera looks really nice though, I’ll try it out!

Markbroussard: Thanks, worth testing, previously my main gripe with ritamulse and similar emulsifiers have been very rub in characteristics. 

[Zink]

The biggest effect could be from the partial hydrogenation, it’s possible that the other butters would peform similarly if similarly hydrogenated. 

[Zink]

Thanks Mark, this is interesting!

It should be noted they compared 2% moringa butter to 5% petrolatum

And that the study was done by the company selling the product and that there are no other studies looking at moringa butter and tewl that I can find.

It’s not known how it compares to other exotic butters such as Cupuacu butter.

[Zink]

Rest is just water. Increasing alcohol is an option, but afraid it could make it more irritating.