[Pharma]

Thanks! That’s exactly what I was looking for.

But it’s the infamous sucrose laurate :'( . Nonetheless, it gives me a rough idea and that’s what I was hoping for.

[Pharma]

MarkBroussard said:

…If you took that approach, then every product could be deemed stable if you simply continue lowering the test criteria at which you deem something to be stable until your product passes.

Isn’t that common practice? *cough-cough*

[Pharma]

@Doreen is 100% correct

[Pharma]

What if 50°C is close to phase inversion temperature?

[Pharma]

Melting point 60-70°C for the whole oil phase?

How does consistency change of the pure oil phase @ 50°C compared to RT?

What type of emulsion do you have? Probably lamellar… 50°C seems high to me but that’s from a different point of view (pharmacy v.s. cosmetics).

[Pharma]

That’s not an overhead stirrer but a magnetic stirrer. Wrong link?

[Pharma]

Me, I never had any success when using patents as guidelines/starting point for stuff to create (wasn’t cosmetics, though).

[Pharma]

@Perry: Just stumbled upon the book “Handbook of Cosmetic Science and Technology” by Barel, Paye and Maibach.
Chapter 20 and 21 are about skin pH.

[Pharma]

Gritty is usually zinc oxide. What you can try: Take a spoonful and put it on a very flat surface like a glass plate -> rough milk glass is actually better because it helps rupturing aggregates. Now spread it very thin with a straight-edge tough spatula or similar. You’ll see “empty” traces if there’s large zinc oxide agglomerates. Do that over and over again until the thin layer is homogeneous. Way back in old apothecary times, this was how you did it. Some months back, lacking a three roll mill which does the same but faster and without manpower I had to do it myself (well, as superior I had the apprentices do it :smiley: ) when preparing a 50% salicylic acid vaseline which is basically the same regarding handling. Even looking at the poor girls smearing spoon by spoon by spoon made me sweat! It took them forever to make those 100 g. (I know, that was evil but they needed to learn something… like don’t trust your boss if he asks “Wanna make some ointment? It’ll be fun!”)

Quality beakers are very heat resistant, a stove is way better than open flames because of even heat distribution an no soot.

[Pharma]

It’s a shampoo, it’s supposed to contain detergents i.e. substances which dissolve lipophilic aka oil-soluble matter such as dirt, sebum and ketoconazole.

[Pharma]

Back from a walk with the dogs and some fresh air…

Sure, heating everything works too, reduces eventually present germs and is probably easier/faster with larger batches. On the other hand, I for my part like cold processing. Adding the native butters later seems just more gentle and requires less heating/energy whilst speeding up the cooling process.

Given that all your main ingredients are heat stable enough, any strategy will be okay. @MarkBroussard had a good input regarding stick blenders and air inclusions!

The thing with zinc oxide is this: There are many different qualities available and some are quite hard to disperse evenly (not necessarily visible by the naked eye). If you have a suitable product, an overhead stirrer can certainly do the trick. Probably I was just unlucky and always got the “bad” stuff (although pharma grade) which required quite a bit of energy even if sieving beforehand.

I had an idea (let’s see what more experienced people think of it): Adding GMCY in the beginning might be helpful: It’s a heat stable emulsifier and wetting agent and therefore might help with dissolving sterols and wetting zinc oxide particles.

[Pharma]

Did you dissolve the sterols in the hot oils?

The mildest version would be to heat up coconut oil to ~80°C and add the sterols, mix until dissolved (pure sterols won’t melt @ 80°C but rather slowly dissolve whereas pre-made pastes will). Once finished, stop heating. Now you have two possibilities, each with its advantages and disadvantages:

Version 1: add the butters (which should readily melt) and then sunflower oil. The mixture should now be at around 40°C if I calculated well. Then incorporate zinc oxide and once at room temperature finish by adding the rest. Because of the higher viscosity, this strategy is often chosen when using a three roll mill for homogenisation of zinc oxide or other clumpy powders.

Version 2: After turning down the heat, start by adding sunflower oil and zinc oxide. Because that oil mixture is of low viscosity, it will wetten the zinc oxide particles better and also results in a fairly thin suspension which is easier to homogenise with a stick blender. Then proceed by adding the butters and finish with the rest once cooled down.

Depending on how finely you disperse zinc oxide, viscosity of your balm will be more or less different. I can’t calculate viscosity or melting point of the mixture because of the fractionated coconut oil which can be of very different quality in terms of said parameters. With native i.e. solid @ RT coconut oil I would guess that your balm without the zinc oxide is a soft butter once “ripened”: It is possible/likely that your balm settles to a more solid form after a few days due to formation of microscopic fat crystals. Especially cocoa butter has a weird behaviour regarding crystal structure/form: Depending on the speed of cooling and the mixing during cooling, different types and sizes of crystals ripen and the resulting butter gets coarser/grainier of softer/smoother. That’s one of the reasons why there’s good and bad chocolate .

Just in case you want to go super safe: Heat zinc oxide in the oven to “sterilise” it as I mentioned in one of my first posts.

Whether or not you should heat everything except the preservative/antioxidant I honestly don’t know. Likely not but I lack practical experience (in cosmetics, practical experience is often more valuable than theory).

[Pharma]

Detergents .

[Pharma]

Blendia by Kai is said to be great, looks like a hybrid between an Ultraturrax and a stick mixer… alas, once I found out, its production has been stopped a months before ;( .

Another recommended one are certain models of ESGE Zauberstab and Bamix. These are high-speed (>10’000 RPM) stick mixers with relatively low wattage in case of ESGE whilst Bamix has for example a 360 W model with 22’000 RPM. Both are super robust and look very old school. They are in fact so old school that you can still use granny’s replacement blades on the new models and they are so robust, you can use a new replacement blade on granny’s still working mixer .

I’m actually searching for a suitable model myself and am considering Steba MX 21 and Gastroback 40976 Design Advanced Pro E. They have reasonable prices and each its advantages and disadvantages. The former has exchangeable blades (I could probably make something high-shear of my own?) and unfortunately starts already at 4’000 RPM and goes up to 13’000 RPM with a power button for 16’000 RPM. The latter has two exchangeable sticks, one normal sized and one with a nice small sized head for emulsions and small home made batches and starts at a low 800 RPM and goes stepless up to 15’000 RPM. Has anyone ever tried one of these?

[Pharma]

Is it really foam or could it be oil drops (i.e. emulsion is not stable)?

[Pharma]

It does have better degreasing properties than plain water… on the other hand, did you ever mix glycerol and oils? What happens if you do?

[Pharma]

Well, it could be that the top layer of “rust” has now been removed and there’s no more iron coming off the container.

That it starts at the top is fairly obvious: Abrasion is either pure steel or can be iron citrate which especially together with antioxidants in your mix will be iron(II). Hydroxamate-iron(II) complexes are expected to be way less coloured. Once you have air (even if the container is closed, there’s enough left over oxygen), iron(II) oxidises fairly quickly to iron(III) and these complexes have that orange-brown colour.

I’ve seen friction coming off of a polished stainless steel container whilst mixing with a low shear teflon scraper after maybe an hour or so. Didn’t stop but got fainter after several runs. It’s that molecularly thin protective oxide layer which makes stainless steel stainless (LoL, so much for “stainless”).

It won’t matter when you add caprylhydroxamic acid.

[Pharma]

The simple DPM without methyl ethers has higher hydrophilicity and therefore less power to solubilise lipids and fats such as smashed bugs and flies.

Hence, the alternative product is likely to be less efficacious in cleaning.

[Pharma]

I second what @JonahRay said.

You might have some wear of friction in the larger processing machine and caprylhydroxamate reacts with it to give that strong colour.

[Pharma]

Good question, I wonder the same thing. Tried such a product once but can’t remember what it was… I can remember that there was seemingly nothing “crackling” in the INCI. Probably the propellant plus a semi-stable foam which causes implosions?

[Pharma]

They simply stick on the surface awaiting their turn. Many microbes have spores and other long-term survival forms and/or can cope with tiniest amounts of water and nutrients to survive a very long time.

[Pharma]

@Aziz Just a small note: Vitamins and provitamins require living tissue and most are usually only active when eaten. It’s like pouring gasoline over your car instead of into the tank. There is a small chance that when drowning your car in enough gasoline, some will actually diffuse into the tank. In addition, the slippery covering over you car does reduce air friction: From a twisted scientific point of view, it is hence proven that showering a car in gasoline has it run longer and faster. It’s the same with panthenol .

[Pharma]

They’re fairly similar and switching might be possible with only minor adaptations. For what do you need DPM?

[Pharma]

Having an intact “acid mantle” i.e. slightly acidic pH on the skin helps reducing microbial growth. Absence of an acid mantle is allegedly (I say allegedly because I haven’t read anything useful since I can’t read everything) linked to increased (infection related) skin disorders.

On the other hand, we’re in the era of probiotics and talk also about skin microbial flora… as it seems, an intact microbial flora (not just on the skin, but everywhere where we have microbes) is a more effective protection from “bad” microbes. A lower pH allows for the growth of lactobacilli and these are often the “good” guys -> a low pH would go well together with the skin microbiome hypothesis.

BTW “balanced pH” is a stupid marketing term and means nothing.

[Pharma]

From a chemical point of view, they are heat stable.

Hot processing might however force them into the oil phase and thereby reducing preservation efficacy. Adding enough glycerol or other polyols can (doesn’t necessarily have to, though) reduce this drift.