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I talked to Ashland, looking at the formula they recommended V216F and Z220F over WP-660. Do you have experience with the latter?
What benefit do those esters have over plain oil isododecane?
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I will test all squalane vs all caprylic/capric, i wonder if there are any theoretical benefits of the latter over the former though.
The problem with synthetics is that they’re often not available “over the counter” and if you end up using several of them, the MOQs can be prohibitive to new, initially small scale formulas.
Will let you know what I learn.
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I’m going to keep this simple and assume basic electronics knowledge:
UV Sensor: https://www.adafruit.com/product/1918
Breadboard: https://www.adafruit.com/products/64
Fan: Delta 25 mm, 5 V, AFB02505HHB http://www.ebay.com/itm/272241928073?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
365nm UV Flashlight: https://www.amazon.com/gp/product/B01FH2NHWS/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
Tube (spraypainted black): https://www.mcmaster.com/mv1478814336/#catalog/8532K21
Enclosure: https://www.mcmaster.com/mv1478814336/#catalog/7593K27
3M Transpore Tape: https://www.amazon.com/gp/product/B005OFM6JE/ref=oh_aui_search_detailpage?ie=UTF8&psc=1Most 2.7 - 3V DC power supplies will work, you could also use two 1.5V batteries in series. Everything shares the same ground. Any multi-meter will do.
Setup with nothing covering the sensor, stabilizes at 198 +/- 2% mV after 5 minutes (temperature of led stabilizes).
The flashlight screws apart and is mounted in the center of the enclosure, breadboard hotglued in place.
Sensor covered by 1×1″ 3M tape, reduces mV reading ~10%.
Smear 10 mg of your formula homogeneously across the center using a small spatula. Do at least two samples per formula to make sure you’re getting repeatable results. In my experience results are usually within 10% of each other; fine for my use. I was able to get from 45 to 15 mV (!) for my 10% ZnO formula.
For reference a SPF50 mineral sunscreen gets around 18 mV. A SPF 27 sunscreen around 40 mV. Keep in mind organic sunscreens usually perform 2-3x better in this type of assay. And it only measures UV-A performance with its 365 nm peak wavelength.
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@Belassi think you were correct, xanthan gum fared a lot better!
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Fixed the Chinese unit, chuck wasn’t seated all the way up the spindle from the factory. Now runs totally true and quiet and it actually goes up to 3000 rpm. 4.5/5.
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I only see this with Triethoxycaprylylsilane coated ZnO, non-coated ZnO is fine. Could try Xanthan Gum instead.
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$160 including shipping, variable speed from 530-3100 RPM with LED readout. I mean what more could you ask for - changing beakers has never been easier
No lotion too thick lol.I tested the Generic Chinese unit described above, comes with an external 110 - 220V PSU outputting 24V DC, 72W. Can be overclocked to run at 2750 RPM through the menu. Silent brushless DC motor and nice timer feature, but too much run-out (spindle wobble) for my liking causing vibrations at certain RPMs. If not for that it would have been 5/5.
Tip speed with 55 mm sawtooth disk:
Circumference = 3.14 * 0.055m = 0.173m
Speed = 0.173m * 2750 rpm = 475 m/min or 8 m/s -
Actually found a $600 homogenizer that goes from 300 - 23000 rpm http://www.ebay.com/itm/2016-New-Lab-Homogenizer-Disperser-Mixer-AD200L-PN-300-23000rpm-12-18G-220V-A-/282052997980
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Not a good option for small scale sample making which Is what I’d use it for:
Rotor/Stator won’t fit into small vessels.
Higher minimum speed.
Slow China shipping, and imagine warranty returns, lol.Other emulsifier/homogenizer options are typically repackaged dremels with 5000 rpm minimum speed or used giants which require $500 rotors to work. At that point you might as well use an industrial immersion blender instead.
You could get a 40 - 6000 RPM overhead mixer used for $500 on ebay though: http://www.ebay.com/itm/Caframo-Ultra-Speed-Digital-Stirrer-BDC6015-40-6000-rpm-/232010563536?hash=item3604e83fd0:g:0SMAAOSwyKxXhQm-
New $1500.
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Found a decent deal on Amazon: Generic Chinese brand 100 - 2500 rpm 60W mixer with digital readout, 110 - 230V, 2 yr warranty for $440 including shipping, impeller and stand.
https://www.amazon.com/gp/product/B00CF3J07E/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1And a 8 mm shaft 55mm sawtooth disperser for $64 (I bought the last one)
https://www.amazon.com/gp/product/B00CF3J07E/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1Seems like a good deal for the home gamer / semi-professional who only use the tool on occasion. One concern, is there any need for higher RPMs?
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Ok I will do a simple writeup or instructable this weekend
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@crisbaysauli looks like a great solubilizer, what’s their MOQ and price/kg? My issue is that the Triglycerides are part of a proprietary fragrant extract blend.
@Chemist79 it’s a cleanser so it’s wash-off hence I wouldn’t be concerned with stickiness, I’ll just have to get my makeup kit out and give the combos a try lol.
crisbaysauli also suggested a polyglyceryl caprate, what are the benefits over Decyl Glucoside?Many thanks!
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Alternatively you could use Polysorbate-20, I think you’ll just have to try it and see if there’s any visible separation. Oh and let me know if you figure out how to avoid tackiness from L-Ascorbic acid!
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@Belassi Why not? You tell me! I see EWG is a bit concerned about it but I don’t know if their concern has any validity. What use rate would you estimate it’d make a difference at? Say if using 10% Decyl Glucoside.
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Thanks ya’ll will contact them. Also seems like most sizable supplement manufacturers have “flavor chemists” in-house, which would probably be the most affordable option.
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@Bobzchemist I thought about adding a bit more oils or esters, e.g. Caprylic/Capric Triglyceride which is already in the aromatic extract blend. Think increasing the amount a couple % could work? Only thing is that it clouds the formula a lot.
@Chemist79 how about just adding more glycerin?
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I see, definitely not apples to apples then.
Regarding coating, I think it depends, the silica/silicon based ones would likely be coated in typically Triethoxycaprylylsilane, but silica/silicon free dispersion seem to be coating-free, typically using Caprylic/Capric Triglyceride and Polyhdroxystearic Acid as dispersants. Correct me if I’m wrong.
Regarding safety/ROS production/genotoxicity, I just found a paper saying that silica or alumina coated TiO2 from sunscreens was basically inert as you say, whereas presumably uncoated ZnO generated significant amounts of ROS when exposed to UV: http://www.sciencedirect.com/science/article/pii/S1010603013001810
So IF either mineral is robustly coated, you needn’t worry about safety and can focus on UV protection; TiO2 is more effective at attenuating UVB (10 - 30 nm size due to its high refractive index), so you can get away with a lower total mineral content and improved skin feel when combined with e.g. 200-300 nm ZnO which takes care of UVA without being too white for comfort. This paper goes on to describe a method to do this effectively using 15% nano TiO2 and 85% micro ZnO blend (not sure you can get the effect with coated materials, maybe there are premade dispersions of both that exploit it) http://www.sciencedirect.com/science/article/pii/S0366317516000133
Back to the drawing board!
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Thanks Bill!
I’ve seen several sunscreen manufacturers say that in-vitro results are at least 3x lower than in-vivo with mineral only ZnO sunscreens, when you say correlate well, do you mean it matches? Were these ZnO only formulas? And if what kind of SPF/% ZnO did you get?
It seems like the difference between Xanthan Gum (in the control) and Sclerotium Gum in my formula wouldn’t make a world of difference. DOW tells me “most carbomers” can complex with Zinc ions, so I’d need an alkyl functionalized variety? Veegum is an interesting option, noted.
Ideally want to avoid TiO2 due to long term toxicity concerns when used in a daily wear formula.
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Ordered samples of propanediol dicaprylate, Neopentyl Glycol Diethylhexanoate and Diisopropyl Adipate. Any usage rate estimates would be helpful.
Made a different version of the formula where shea and castor seed oil got replaced by microcrystalline wax and caprylic/capric triglycerides respectively. Will see tomorrow how it compares!
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No worries, it’s available on ebay at all places, 5 g for $15 incl shipping. Going to see how much I need to use for it to make a difference.
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@Bobzchemist thanks, very useful info, might revisit it, could potentially help with ensuring long term green-ness.
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Yes, nothing special here, move along..
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Thanks Bill! I guess you could make two samples with and wo Chlorhexidine, incubate them at 40C for a week and have the Benzoyl Peroxide % assayed by HPLC ($125/sample)?
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@wbliss wouldn’t that make the formula more unstable by having to deal with ascorbic acid-in-water oxidation? Otherwise I like the idea.
@johnb do you have any good methods or are you saying google it?@Bobzchemist I had some at one point, but seems like it’s cost prohibitive or do you know any good sources?
BTW Sodium Metabisulfite still does the trick, but the sulfur gives it a sharp and undesirable scent that must be masked.
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Interesting, anything that’s more readily available? Seems like both of those only come in 35 lb pails and this’ll be small scale to begin with.