Magnesium/MSM Cream - Preservatives & pH?

Zaf · August 2019

Hey everybody. I'm working on this thing that's completely gotten away with itself and I was hoping that someone might be able to look over what I'm doing and give me some pointers. I've done an enormous amount of research and the ingredient list has gotten quite large, so I apologize.

INCI: Theobroma Grandiflorum Seed Butter, Aqua, Olea Europaea Fruit Oil, Shorea Robusta Seed Butter, Vitus vinifera seed oil, Magnesium Chloride, Zinc Oxide, MethylSulfonylMethane, Simmondsia Chinensis Seed Oil, Nymphaea caerulea Flower Extract, Aloe Barbadensis Leaf Extract, Avena Sativa kernel flour, Bambusa Arundinacea stem powder, Persea Gratissima Oil, Cannabis Sativa seed Oil, Hippophae Rhamnoides berry Oil, Ascorbyl Palmitate, Thocopherol, Cholecalciferol

Wax:
2 Tbsp - Sal Butter
2 tsp - White Lotus Floral Wax
1 1/2 tsp - Jojoba Oil
3/4 tsp - Avocado Oil
1/2 tsp - Hemp Seed Oil
1 Tbsp - Non-Nano Zinc Oxide

Water:
2 Tbsp - Purified Water
1 Tbsp - Magnesium Chloride
1 Tbsp - OptiMSM
1 tsp - Colloidal Oat

Base:
4 Tbsp - Cupuacu Butter
3 Tbsp - Unfiltered Olive Oil
2 1/2 Tbsp - Grapeseed Oil
1/2 tsp - Vitamin E Oil (T-50)
1/2 tsp - Vitamin D3 Oil (in Olive Oil)
1/4 tsp - Vitamin C (Ascorbyl Palmitate)
1/4 tsp - Sea Buckthorn Berry Oil
1 tsp - Aloe Vera Juice Powder

1 tsp - Bamboo Extract Powder

- Wax and Sal butter (which is much like cocoa butter) is melted, then other ingredients added.

- Water heated, minerals added to dissolved, add to wax in blender, add oat, blend till smooth.

- All butter ingredients (Cupuacu is much like Shea) go into a standing mixer, mixed till incorporated, emulsion added slowly and mixed on medium speed so butter doesn't get grainy.

Here's my question:

I know that OptiMSM can be used as a preservative. It sounded to me like 10% is the minimum for this purpose (and ideally higher?). The current recipe has it at 5%. It sounded like this is not sufficient... it's being used in cultures, but my question is this: is it used in cultures because it discourages other microbes/ect so that the viruses they're growing (flu?) have a better chance at growing? Hence still having some microbial action?

As for the water portion of the emulsion, it comprises a much less significant quantity (about 10%)... and thus, by using some hurdle technology (low water content, other perishables suspended in the oil portion of the emulsion, additional salts via magnesium chloride) would maybe be sufficient preservative to keep for at minimum six months in less than ideal conditions (left in a car, kept on one's person in the heat, ect)?

The first batch of this I made did not include the oat, but had the aloe in the water portion. It has not grown mold as to yet. As a test, I left them empty container (which obviously has a thin coating of the cream) in my car. I made it about a month ago, and there hasn't been any signs of spoilage (but I not regret that experiment... it's a 4oz canning jar, so airtight).
I had also used magnesium sulfate for the magnesium component - I understand that both MSM and Magnesium Sulfate contain a sulfur component that acts to preserve the water portion.

I was also looking at adding a probiotic and was wondering if that would boost it's "shelf-life", or if it would be a better choice to add something like AMTicide, thin it out (with liquid oil), and throw it in a pump bottle?

I don't really want to add more water to increase the MSM content and not sure that it and the magnesium will totally dissolve and not separate out when added to the oil (and turn grainy) if I push the quantities too high.

I am considering adding Tumeric EO (Co2 extraction) to the mix but I'd like to keep it to 1% to avoid irritation since I formulated this for use with Psoriasis, which tends to sting like the dickens.

Furthermore: how the heck do I even test something thick for PH? Could a fruit juice powder or freeze dried fruit powder effectively lower the PH without having to add pure citric acid/ect, or perhaps an Orange EO? And does it matter that much in a topical (I do understand the acid mantle is a thing)?

Sorry for the novel. At least it's thorough?

Thank you so much for any help you can offer!

Zaf · August 2019

I'd like to apologize for all the grammatical errors... I typed this on my phone and Swype hates me. ?

Zaf · August 2019

I am aware that I made some mistakes as well:

The Vitamin C will have to be added to the heated oil portion it sounds like to get it to mix.

Sorry I'm a total newb. I started with anhydrous formulations but the concept of adding magnesium to my butters was just too good to pass up. It's exploded from there (with the addition of bamboo and changing up some of the oil/mineral types).

I'm trying to build something with a whole lot of anti-inflammatory properties and the main importance is that everything is as non-irritating as possible since psoriasis compromises the skin barrier (think papercuts, extremely sensitive)... and of course, I don't want it to mold!

I also wonder if going back to magnesium sulfate with the MSM would add enough sulfur to do the job?

I'm willing to change up the formulation and ingredient for less spoilage. I recognize that it's probably WAY TOO ALKALINE. I do think I would like to keep it closer to 6pH rather than dropping down to 5pH. I recognize that this would open up my options for preservatives as well. I have no idea how to calculate it off-hand without testing it to get an idea of where I'm starting and how much it'll have to drop to be more friendly to the skin barrier - especially with two components that would draw all the ingredients deeper into the skin.

Pharma · August 2019

Zaf said:

...
Water:
2 Tbsp - Purified Water
1 Tbsp - Magnesium Chloride
1 Tbsp - OptiMSM
...

First: Please don't use "spoons" as a measure! For example, rough salts have a different weight than finely ground salts. Hence, if you're posting here, re-calculate in grams and you'll get better answers!

Second: Approximately 1 part water to 1 part MgCl2 & MSM drops water activity to a level where nothing will grow; adding more water to be able to add more MSM doesn't make a difference because the oil phase doesn't count. Using MgCl2 (but not MgSO4) will also drop relative humidity in the headspace to ~35% and that is enough to stop fungal growth there. A 30% solution of magnesium chloride is self-preserving and doesn't require additional preservatives. But this is true for pure MgCl2 solutions and not necessarily mixtures such as yours.

Sulfur from MSM and sulfate doesn't impart any preservative action. Salts and MSM simply drop the free water proportion by being solutes and that's it. One hurdle and one hurdle only (a good one, I have to admit that).

Your formula might still not be stable since you have no emulsifier in it and this might result in small droplets of purer water forming somewhere and then, you'd risk having microbial growth there. At least consider adding something that weakens or even kills microbes and don't just rely solely on water activity which simply stops them from proliferating but not from existing.

I don't know what you mean with "MSM is used in cultures" and what's that thing with "growing viruses/flu" (flu doesn't grow in a cosmetic product)?

pH in your water phase is something you can neglect here since it only reflects the pH of plant extracts and probably ascorbyl palmitate. It's a small proportion and skin pH will automatically adjust shortly after applying your cream. Having it acidic will be good for preservation but you can't really determine pH in your mix. Even just measuring pH of your water phase (plus the plant extracts) will be off (too concentrated solution) -> you will have to dilute with pure water to get a better idea of the "true" pH.

MarkBroussard · August 2019

@Zaf:

You have chosen perhaps one of the most difficult creams to make ... not a good place to start for a beginner.

I've developed a few MgCl creams and they are not easy formulas. As regards pH ... the pH of a 30% MgCl solution is 4.0. You have a pH incompatability between the MgCl and ZnO which is most stable at a pH of 7.0. So, you'd best ditch the ZnO.

Your biggest problem is that you don't have an emulsifier. You'll need to mix your waxes and oils together with an emulsifier(s) and a touch of water to form the cream. You might try Glyceryl Stearate and Glyceryl Oleate. Once the cream is formed and completely cooled down to room temperature, slowly add the MgCl solution in small aliquots and mix in. Then add a bit more and mix in. Keep doing this until you have added all of the MgCl solution.

MgCl readily breaks emulsions which is why you must add it to a cold cream and in small increments at a time. The cooled cream will be crazy thick and even after you add the MgCl solution it's going to be "lumpy" so you'll want to process it further to create a "smooth" cream.

Your next biggest problem is some confusion as to what is and what is not a proper preservative.

Zaf · August 2019

Thank you so much!

The first try kept perfectly and did not separate out. Considering I've never tried this before, I was really surprised.

I absolutely do not have ANY IDEA what I'm doing (my interest is in health mostly, not chemistry!)! I'm kinda learning in the fly - luckily this is kinda a hobby for me so it's fun.

I couldn't find much on a magnesium cream and how to make it asside from the fact that they probably need a preservative and that the water and wax phase need to be approximately the same tempature to mix without an emulsifying wax. I did find some posts on this board that we're dealing with some similar ingredients and figured that this was the best place to get some answers that I wasn't finding through my own research.

I have considered switching to an olive-based emulsifying wax. I'm trying to keep each ingredient to have some purpose for the skin. Not sure if the processing that emulsifying waxes removed some of the characteristics from the original source. White Lotus is anti-inflammatory (as is nearly every other ingredient), it was a replacement from beeswax... though I suppose it can always be switched out again.

So, if the issue is free water, would it be correct to say that it probably doesn't need a preservative for the kind of shelf-life I'm looking at? I was trying to be in the safe side because I am on immuno-supressants and don't want to slathering a whole lot of nasty microbes onto my skin (nor my son for that matter). I'm also considering sending some to some friends who have shown some interest (through the mail, maybe with an ice pack because I'm working with a high polyphenol Olive oil that might degrade a bit with heat)... not sure if that makes any difference.

Zaf · August 2019

Also: is the zinc really a problem? It's kinda an important component to form a moisture barrier and an extra soothing component (I find it works quite well for broken skin, I use it in all my anhydrous butters). I'd really like to keep a zinc component for that reason.

Also: I do plug this into a calculator for percentages. I'll fix it next time so that it's by weight. I can post the percentages if that would be more helpful.

Gunther · August 2019

Please list and weigh ingredients in grams/milligrams as tablespoonfuls aren't accurate.

AFAIK salts like Magnesium salts aren't absorbed well by the skin.
So please look up for studies on its absorption (i.e. at Pubmed). If Mg salts aren't well absorbed then you can sharply reduce its percentage, even as low as claim ingredient levels because it ain't really doing anything useful in the formula.

Zaf · August 2019

I did read up on it and it did sound like magnesium sulfate (generally in the form of a bath) and magnesium chloride do appear to work, to some extent, for transdermal... though obviously the research to date appears to be equal on both sides as to if it does or doesn't (mostly in that a lot of studies said they don't suggest it because of poor absorption). The impression I got was that about 30% gets through (though, again, the study I read that got this kind of quality was through using Epsom in a bath - I'm sure that soaking allows the ingredients to get deeper. I figured the MSM and Jojoba would help for this purpose as they're supposed to help penetrate the skin barrier.

Ya guys are kinda making it sound like I should scrap the magnesium and msm and just go back to anhydrous formulations. ?

Zaf · August 2019

Also: the mention about cultures...

I was reading up on MSM and it's purpose as a preservative and came across studies on cell cultures - obviously this has nothing to do with topicals nor cosmetics. They were using about 1-5% in the cultures growing H1N1 (flu virus) and using it in some way to encourage the virus growth... at least that's what it sounded like.

I'm not totally sure what the mechanism there is. MSM is a totally new ingredient to me that I've been looking at playing with for awhile. I had considered DSMO for a bit but decided that it was too dangerous to work with because it increases penetration too much and can cause nasty stuff to get into the blood stream. I do understand that MSM crosses the blood-brain barrier but it sounded like that's oral use.

Pharma · August 2019

Zinc oxide may form organic zinc salts at low pH (likely, only a small fraction will react) but since a low % of for example zinc sulfate is allowed in cosmetics, it shouldn't be too much of an issue... but then again, who knows without knowing?

If you have enough wax in your oil phase, what you get is similar to a traditional cold cream, a pseudo-emulsion without emulsifier which becomes fairly stable due to the oil phase being solid enough to prevent water droplet movement/fusion/sedimentation.

Personally (and I really mean that in a subjective way), I'd add glyceryl caprylate, pentylene glycol and Cosphaderm magnolia extract 98 (does also exist as pre-mix Cosphaderm MultiMEG). You don't need much because you have a very small water phase. The proposed % to be used doesn't always have to be with regard to the total but just to the amount water phase especially with highly water soluble preservatives and if you're only using it because, as we say, double-stitched holds better. Well, magnolia extract (composed of mostly magnolol and honokiol) is oil soluble and therefore, this rule of thumbs doesn't apply. The upside is, that magnolol and honokiol are anti-inflammatory and you might want to add more anyway

. Glyceryl caprylate isn't fully water soluble (though it probably is in a water/MSM mixture) but because it should also serve as emulsifier, not using less seems also beneficial.

Magnesium does go into upper skin layers but it doesn't penetrate through them. Small quantities can be found in the bloodstream but magnesium being more of a quantitative than a trace element, such small quantities don't do anything. I read quite a bit about topical magnesium: It's a dream unless you're using it for topical effects.

Besides, MgCl2 does perform better than the sulfate and it can show synergism with glycerol, urea or pentylene glycol

.

Regarding anti-inflammatory activities: Facts point toward MSM not just being the main metabolite of DMSO but also for being the active form of DMSO. To be on the safe side, go with MSM since it's safe and does penetrate skin well.

I don't know that publication about flu viruses and would have to read it to be able to explain anything. One factor might be that MSM has properties of osmolytes and these can have effects on virus viability or shedding. But osmolytes have many more effects, for the most part very beneficial for skin

.

Zaf · August 2019

Ingredients by %

Water:

Water - 10.21

Magnesium - 5.11

MSM - 5.11

Oat - 1.7

Wax:

Lotus Wax - 3.4

Sal Butter - 10.21

Jojoba - 2.55

Avocado - 1.27

Hemp - 0.85

Zinc - 5.11

Vit C - 0.85

Base:

Cupuacu Butter - 20.43

Olive - 15.32

Grapeseed - 12.77

Sea Buckthorn - 0.85

Vit E - 1.7

Vit D - 1.7

Aloe - 0.43

Bamboo - 0.43

When I make it again I'll weigh it so that I can have the correct quantities, but this should be relatively accurate to what %s I'm looking at.

Zaf · August 2019

By grams this should be (note kinda aprox as a TBSP isn't a perfect 15 grams, ect):

Water:

Water - 30

Mag - 15

MSM - 15

Oat - 5

Wax:

Lotus Wax - 10

Sal Butter - 30

Jojoba - 7.5

Avocado - 3.75

Hemp - 2.5

Zinc - 15

Vit C - 2.5

Base:

Cupuacu Butter - 60

Olive - 45

Grapeseed - 37.5

Vit E - 5

Vit D - 5

Aloe - 1.25

Bamboo - 1.25

I'm guessing I'm going to have to round out the odd numbers so it weighs out correctly? (Example: bumping up 2.5 grams to 3 grams, ect... at least to make it easy on myself?)

Zaf · August 2019

Thank you so much Pharm! I will look into all of that and see what changes I want/need to make! That is all super helpful!!!

So the problem with the zinc is specifically the oxide?

I did read up on magnesium oxide as an alternative, it didn't sound like it's used as often but sounds like it might have similar qualities to zinc in forming a moisture barrier and encouraging healing.

Though this might explain why the first few days of this cream's life I needed to mix it in thoroughly so that it didn't leave a white film... and about a week in this quality completely disappeared. Perhaps it reacted and changed to a sulfate? It sounds like zinc sulfate isn't nearly as safe as zinc oxide so... yeah, might have to go (magnesium turning into sulfate would be much more preferable).

Zaf · August 2019

Ok, no, maybe the whole oxide component needs to go. ? That's some strange chemistry stuff I probably don't want to mess with (I can read a medical study but tried to pull up a paper on magnesium chloride and magnesium oxide reactions and realized that I can't read about 50% of this!).

Thanks for the heads up!

Zaf · August 2019

If I switch back to a magnesium sulfate, boost the levels maybe (to 10%) and with the addition of the MSM get a decent absorption? I'm not going for raising systemic magnesium levels (not that there's anything bad about that - it's certainly a bonus), but hoping to get it past the skin to the soft tissue... and with an emulsifier get it to not go gritty (or add just enough water to incorporate)? I kinda want the soft butter to remain the largest component. Too much water and it seems to break the moisture barrier.

Gunther · August 2019

Zaf said:

If I switch back to a magnesium sulfate, boost the levels maybe (to 10%) and with the addition of the MSM get a decent absorption? I'm not going for raising systemic magnesium levels (not that there's anything bad about that - it's certainly a bonus), but hoping to get it past the skin to the soft tissue... and with an emulsifier get it to not go gritty (or add just enough water to incorporate)? I kinda want the soft butter to remain the largest component. Too much water and it seems to break the moisture barrier.

Too much guesswork
You may wish to read the studies cited here
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579607/
and fully replicate the formulations that have fairly good absorption, because not all do.
Don't take the article as is, as it's just a review article. Please read the studies cited there.

Pharma · August 2019

Grittiness is best avoided by using enough water, an emulsifier won't help with salt crystals. Magnesium chloride is twice as water soluble as the sulfate

.

Magnesium oxide will react faster and fully with acids whereas zinc oxide tends to be slow and superficial (different solubility, different crystal structure etc., though a paper sketch formula won't show any differences). If you want something even less reactive, titanium oxide might be a workaround (though it's no longer considered as inert as we used to think, same story as with zinc oxide a while back...). Or switch ascorbyl palmitate with ethyl ascorbic acid (not acidic anymore) and use a batch of magnesium chloride which has a neutral pH. In theory, MgCl2 in solution is neutral! Acidic solutions are due to traces of other salts, probably hydrochloric acid (?), or other impurities present at possibly up to 5% but not caused by MgCl2 itself. Neutralising these with whatever pleases you should solve the issue. Besides, theory says that MgCl2 + ZnO won't react to MgO + ZnCl2 but would react the other way round. The issue of zinc oxide instability might be hiding in the unknown...

MarkBroussard · August 2019

@Zaf:

Here's a formula that was used in this referenced pilot study:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5389641/

Magnesium Cream: Lot # T10224: Aqua, magnesium chloride (10%), cetearyl olivate, sorbitan olivate, isopropyl palmitate, emulsifying wax, glycerine, butyrospermum parkii (shea butter), hydroxypropyl starch phosphate, iodopropynyl butylcarbamate, phenoxyethanol, caprylyl glycol

You might want to start with a more simple formulation to begin and then add other ingredients from there. I have developed MgCl cream formulas similar to the above. As I stated earlier, this is a challenging product to make. The alternative therapy market prefers the use of Zeichenstein salts as the source of MgCl.

With dissociated Cl ions in solution, all you need is a proton donor and it'll form HCl and the ZnO will react with the acid to decompose to Zinc Cloride.

Zaf · August 2019

I had actually already read most of those studies in previous research I'd done, but I appreciate it all the same.

I think I have a plan of attack, but I may end up making a couple different batches/creams to test everything and see where it leads me. The recipe was very helpful.

Thank you all so much for your help!!!

Pharma · August 2019

MarkBroussard said:

...With dissociated Cl ions in solution, all you need is a proton donor and it'll form HCl and the ZnO will react with the acid to decompose to Zinc Cloride.

Sounds a bit too generalised to me. Else, you would have problems as soon as, well, you take cosmetic grade ingredients since salt (sodium CHLORIDE) is a very common contaminant. Also, many formulas contain salt... doesn't mean that you have instantaneous and complete decomposition of zinc oxide (or iron springs in dispensers). Sure, a strong enough acid will result in a corrosive mixture (which is chloride ions and protons but not HCl). The problem lies in increased solubility of many metal ions in the form of chloride salts which commonly results in rusting or dissolution of a metal otherwise resistant to certain acids such as aluminium to vinegar, where dissolution in conjunction with salt occurs only because of the protective aluminium oxide (yes, I know, metal oxide) becoming soluble in acidic brine.

Do you have any literature regarding magnesium chloride (or calcium chloride) reacting with zinc oxide? I'd be grateful to learn something new!

MarkBroussard · August 2019

Well, one major difference would be that you are comparing the effect of 10% to 15% Zeichstein Salts MgCl to trace amounts of NaCl if it is used as a processing aid. While NaCl may be a common contaminant, you're talking more on the order of 0.01% or less.

I can tell you from experience having developed 4 commercial MgCl Cream products that the pH of a 30% Zeichstein Salt MgCl solution is 4.0. Simple fact from direct experience.

Belassi · August 2019

Do you have any literature regarding magnesium chloride (or calcium chloride) reacting with zinc oxide?
If this happened it would produce magnesium oxide + zinc chloride. However ... I think it's impossible, the positions on the electrochemical table imply the reaction can't move in that direction.

Belassi · August 2019

For instance, ferric chloride reacts to replace copper, producing copper chloride, because the series goes Iron-Tin-Copper. For magnesium and zinc it's similar, Magnesium-Aluminium-Zinc

MarkBroussard · August 2019

I think part of the misunderstanding here is the assumption that salts are netural. In fact, salts can be acidic, neutral or basic in solution. In water, they dissociate into the conjugate acid-base pairs. Solid MgCl will not react with ZnO, but dissolved MgCl is an acidic salt. ZnO is soluble in HCl and dissolves to form ZnCl. Since Zeichstein salts are not pure MgCl, there could be other components that contribute to the acidity besides the MgCl itself.

Pharma · August 2019

The electrochemical potential doesn't apply here since the metal ions don't change their 2+ positive charge, whether they are in the form of a soluble chloride salt or an insoluble oxide. According to the electrochemical series, mixing calcium hydroxide or oxide with magnesium chloride wouldn't result in calcium chloride and magnesium hydroxide. On the other hand, it is in accordance with what you @Belassi and I suspect: nothing happens when mixing magnesium chloride with zinc oxide. There are even publications producing nano-ZnO by mixing ZnCl2 with MgO.

It's not about electrochemical potential but mostly about solubility of the oxides and hydroxides and where the equilibria between oxide <-> hydroxides (in the case of zinc, also which kinds hydroxides) <-> free 2+ ions lie.

BTW it's called Zechstein and that is a marketing gag! Most MgCl2 from Europe which has not resulted from synthesis by-products or sea water is mined from a sediment layer called zechstein. It's comparable with rock salt! And stupid consumers believe that sea salt is good and rock salt is bad but rock MgCl2 is good and sea MgCl2 (most US MgCl2 comes from lake water) is bad. In the end, it's highly refined and purified MgCl2 either way. Nothing magic about "Zechstein magnesium" and it doesn't contain more or less whatever there could be. Its pH is simply a matter of contaminants and how it has been purified. Which contaminants cause acidity, I do not know, it could be something like MgCl2-HCl since chloride tends to form complexes with metals but that's speculation. In the end, it's just about pH and how much acid is in there. Small traces of a strong acid can drop pH considerably but will be neutralised in no time.

MarkBroussard · August 2019

I just made a solution of 5% MgCl USP grade ... the pH is 5.0 at 23.8C. The contaminants is the UPS grade MgCl are .005% or less and there really isn't anything in the contaminants list that will for an acid in solution.

I also made a 30% solution of Zechstein salts (my bad on the misspelling) the pH is 4.16 at 23.8C.

I agree that Zechstein salts are marketed quite effectively and that the claims are "creative". But, I do not think that they are refined to the purity of a USP-grade material, so they will obviously contain a higher proportion of "contaminants" ... but that's precisely why consumers in the naturopathic market prefer Zechstein salts.

Perhaps I should not believe my lying pH meter.

MarkBroussard · August 2019

It's a simple exothermic dissociation "reaction":

MgCl2 + H20 = Mg(OH)2 + 2HCl

Water surrounds the Mg ions forming a Magnesium hexahydrate complex and the mixture has a stable pH in the range 4.0 to 5.0

MarkBroussard · August 2019

So, in adding ZnO to a solution of MgCl2 there are two routes to decompositon of ZnO to ZnCl2:

2HCl + ZnO = ZnCl2 + H2O

and/or

MgCl2 + ZnO = ZnCl2 + MgO in a double replacement reaction.

Since Mg is more reactive than Zn, the reaction will be driven to the right.

So, for the OP, no, it is not a good idea to mix Zinc Oxide in your Magnesium Chloride cream ... the Zinc Oxide will convert to Zinc Cloride which defeats the whole purpose of add Zinc Oxide to begin with.

Pharma · August 2019

MarkBroussard said:

It's a simple exothermic dissociation "reaction":

MgCl2 + H20 = Mg(OH)2 + 2HCl
...

Exothermic and it builds hydrochloric acid? Mark, seriously? That's plain ridiculous! Magnesium chloride builds as much HCl as sodium chloride does, which is zip-zero-nada. What it does is form magnesium hexahydrate in water and this behaves slightly acidic but just slightly.

BTW stearic acid does react with zinc oxide. Did you ever consider that?

MarkBroussard · August 2019

No, not at all. Have you ever actually dissolved MgCl in water and measured the pH and temperature or actually made a MgCl cream/product? It would appear that you have not.

Not to be argumentative, but your assertion that the pH drop is from undefined "contaminants" is what is ridiculous ... the chemistry is quite straightforward. And, a simple measurement of pH proves the point.

Stearic Acid & Zinc Oxide ... that has nothing to do with the topic of this discussion.

The Op's issue is whether or not to add ZnO to a MgCl cream ... that's just not a good idea since it is highly likely that the Zinc Oxide will dissolve and would not provide the envisioned skin protectant benefits.

Pharma · August 2019

A: Dissolving magnesium chloride in water is an exothermic reaction. Some salts show this, others are endothermic, and the rest doesn't noticeably change temperature upon dissolution

. This has nothing to do with chemical reactions, it's just disintegration of MgCl2 crystal structure and subsequent hydration of Mg and Cl ions.

B: Pure MgCl2 has a slight acidic pH in water although, according to the simple view of chemistry, it shouldn't even affect pH at all. Depending on water quality (self-buffering, presence of carbonate/carbonic acid) etc., pH can range from 5.5 to 7. If it's lower, it has to be due to contaminants and since most of the common contaminants of magnesium chloride do not affect pH...

C: Sure it does. You advise against something because of possible (according to you quantitative, according to me trace) chemical reactions whilst, I guess, most don't even think about incompatibilities and chemical reactions when combining zinc oxide with very common stuff such as stearic acid which really does react to form oil soluble zinc stearate.

I'm still awaiting scientific proof for your claim of dissolved ZnO.

E: Don't get me wrong: I'm not trying to win a pissing contests here, I'm really asking you because of interest and I won't mime bad loser afterwards (since it's not about winning/losing)

.

MarkBroussard · August 2019

Stearic Acid will react with ZnO at 154C or in the presence of a catalyst such as Phosphoric Acid at 60C to 70C. Neither of those conditions are going to occur in a cosmetic product ... so it simply does not have any significance as it regards ZnO in a MgCl cream product, particularly if the ZnO is added at cool down temperatures below 60C. They simply will not react under those conditions.

I don't know that anyone has ever studied the dissolution of ZnO in an acidic cream product containing Cl ions. But, ZnO very readily dissolves in HCl solution to form ZnCl2. When you dissolve MgCl2 in water, you're going to have Cl ions in solution ... twice as many Cl ions as you do when you dissolve NaCl in water. The hexahydrate of Mg2+ (aq) can form hydronium ions ... protonated water. Since ions in solution are simply charge densities interacting with one another, the dissolved Cl ions will be attracted to the protons ... that's HCl.

Of course, this is not a pissing contest nor a competition ... we're both accustomed to using chemical theory to explain empirical observations.

So, the empirical observation is that a MgCl solution using USP-grade material has a pH of 5.0. Zechstein salts have a pH of 4.0.

" pH can range from 5.5 to 7. If it's lower, it has to be due to contaminants and since most of the common contaminants of magnesium chloride do not affect pH ..."

^^^ Exactly the point ... if the contaminants do not affect pH, then it is not the contaminants causing the pH drop ... it has to be some form of acid.

MarkBroussard · August 2019

Here's some info from BASF

http://creationsnewsletter.com/issue3/3.aspx

pH stability

It is very important to consider the pH of the system when using Zinc Oxide. At pH below 7, divalent zinc ions will migrate into the water phase and cause instability in the system, as Zn2+ can interact with various polymers (rheology modifiers and film formers) and emulsifiers (e.g.salts of stearic acid). Many acrylate-derived polymers are sensitive to Zn2+, forming complexes leading to the disruption of the polymer matrix and loss of stability. These reactions are even more pronounced with the uncoated Zinc Oxide. It has been found that chelating agents (e.g. Na2EDTA) and some salts (e.g. NaCl) in the aqueous phase can help reduce the extent of these interactions. During formulation, the pH of the system may rise, therefore it is recommended that buffering agents such as citric or lactic acid, or others be used.

Pharma · August 2019

That's what I

MarkBroussard said:

...The hexahydrate of Mg2+ (aq) can form hydronium ions ... protonated water. Since ions in solution are simply charge densities interacting with one another, the dissolved Cl ions will be attracted to the protons ... that's HCl.
...
^^ Exactly the point ... if the contaminants do not affect pH, then it is not the contaminants causing the pH drop ... it has to be some form of acid.

Jup, it will form oxonium ions but they do not form HCl since HCl is a stronger acid than magnesium hexahydrate. It's just a mixture of H+ and Cl- and a bunch of other ions as well and not the strong mineral acid required to dissolve ZnO. Mg(H2O)6 is a very weak acid which only has pH drop in water like any other weak acid would. The reaction product of ZnO would be, since there is ample excess of water, Mg(H2O)6 and Zn hydroxides (forms are pH dependent). Since the original acid is not used up but simply acts as catalyst, hypothetically, all ZnO would turn into zinc hydroxides because there would be no neutralisation of the acid. It sounds much like a perpetual mobile machine. Anyway, according to your logic, zinc hydroxides will (and in an isolated model it really would) react with chloride ions to form ZnCl2. Alas, that would leave magnesium hydroxide, a fairly alkaline and poorly soluble product. But, since it has better solubility, it will back-react with zinc chloride to form again magnesium chloride and zinc errr.... hydroxide or oxide? What pH does in the mean time remains speculative. As you can see, it's an equilibrium which is shifted to one side. The question is, which one. As an educated guess I'd say it's heavily shifted to the original state (also because ZnO suspensions don't really show alkalinity). Probably some of the zinc oxide degrades to neutralise pH but it'll be not much because of exactly the same reasoning you mentioned with regard to stearic acid.

My guts still tell me that acidic magnesium chloride contains an excess HCl in the form of magnesium complexes. They are indeed very likely to react with ZnO but are also very likely to be just present in trace amounts. It doesn't require much HCl to drop pH of an unbuffered solution.

@Zaf Try mixing some MgCl2, ZnO and water and see what happens! Would be very interesting! And don't forget to regularly measure pH.

Zaf · August 2019

Will do, Pharma! I also purchased some pH strips so I can relay that as well. I'll be making a small test batch this weekend so that I can decide where to go from there.

I was wondering, since it was mentioned that the Ascorbyl Palmitate has an effect on the pH but is oil-soluble: do I need to just calculate the effect on the pH with the pH from the water portion, or can I test the pH of the entire emulsion?

I also purchased Caprylhydroxamic Acid and some extra vegetable glycerin. I assume I pretty much picked the weakest solvent in that category (and I am fully aware of the sticky quality - I also dabbled in nicotine/vape juice for awhile), but the other options all seemed to be potential irritants (and I personally find glycol to be irritating to my skin, so I'm expecting that others will as well - never had a problem with glycerin though). I figured I'd use it mostly for the extracts I want to play with (I have a list, mostly plantain for the allantoin... surely you see a theme here? LOL), but it sounded like magnesium can dissolve into it... so I'm going to give it a shot to try to keep the water content low but encorporate water-based ingredients without breaking the moisture barrier (so mostly add it as an *addition* to the water content I already have).

Love reading your discussion. Hopefully I'll absorb some of it (now painfully aware that I need to educate myself about chemistry - but hey, it'll give me something to research for the next couple of years). Thanks for being willing to hash it out like that for me. I appreciate it!

Zaf · August 2019

By test the emulsion, I mean the mixture before adding the base portion (which still has oil components and wax). (Just don't want the lotion to sting because it's too acidic... though I might want to drop the vitamin c down to 0.5% anyways?).

Zaf · August 2019

I did the science experiment. From what I can tell, nothing happened? I ended up with a slightly viscous white liquid. The zinc did suspend (stable) in the water, which is kinda unusual but I'm gonna go out on a limb and assume that's just about the salt content in the water. pH was about 6... give or take since reading a pH strip with zinc oxide in it is kinda difficult.

Gotta be honest, was half expecting it to do something unusual, but it was completely uneventful. The solution also didn't feel any different than I would expect from water+salt+zinc oxide. I am working with non-nano zinc if the particle size makes any difference.

Zaf · August 2019

The strips turned a much darker color as they dried (way alkaline (7-8+), not sure if that means anything. Also, totally smelled like zinc oxide, even after about half an hour. The pH of the solution may have gone a little bit more alkaline in that time (it did appear to stay pretty solidly in the range of 6-6.5), but certainly didn't turn acidic. My guess is that the decomp to ZnSO4 is pretty slow. I'm using non-nano ZnO if the particle makes any difference (and pure magnesium chloride since unlike the homeopathy community, I'd prefer to NOT work with contaminates ?).

(Also: wanted to apologize for my brain not functioning, as is likely obvious from my responses... I have a toddler and a whole lot of brain fog)

Pharma · August 2019

Thanks for trying/sharing! I wonder how it changes in the next days. Already great news (IMO) that pH is jumping to 6.

The pH those stripes indicate is only accurate (as accurate as they can manage) instants after wetting. Minutes later, even well before they dry, that value will change to whatever. It's a bit like pregnancy tests

.

ZnSO4? Did you add magnesium sulfate this time?

Regarding toddler: I hear Benadryl works wonders, on both, the parents and the baby. -> Sorry, don't take that serious, I'm joking! Go with Valium instead...

Zaf · August 2019

Did I get the wrong chemical abreviation for Zinc Sulfate (or the wrong number at the end)? I mixed water+magnesium chloride+zinc oxide, in that order. Sorry, I'm confused a bit. I'm trying, I swear. ?

Also: was to the understanding that Zinc Oxide and Magnesium Sulfate don't react to each other (they've used the mixture to protect the skin from chemical warfare?).

And Valium sounds lovely (you don't happen to be a pharmacist too maybe?). ?

Pharma · August 2019

Well, if you mix magnesium chloride and zinc oxide in water and the two would react, then you'd get magnesium hydroxide and zinc chloride, not zinc sulfate

.

Nope, you're correct, MgSO4 and ZnO don't react. Just today, a sales rep visited and she said their product is with magnesium sulfate because magnesium chloride did cause itching and often had to be washed off after 5-10 minutes.

And yes, I'm a pharmacist. Maybe try out valerian first. A sack full over the baby muffles screaming very well and you don't have to change diaper that often either! Seriously, I can feel with you and in such moments I'm happy that we settled with dogs instead of kids.

(Sorry, now I sound like an a***)

Zaf · August 2019

Lol Pharma! Nah, you're fine. It's pretty clear that you're joking. I think I just need to create a portal gun and stick him in a pocket dimension for a bit sometimes. 15 minutes would be pretty good by me.

Kinda funny cus I'm on the other side, glad I don't have a dog right now (I have a cat instead, clearly I like keeping creatures around that have no interest in following direction)!

And thanks for the info. Yeah, that sounds awful and totally not what I'm going for (could you imagine putting that on skin that's already broken and tender... OUCH!).

MarkBroussard · August 2019

Zaf said:

From what I can tell, nothing happened? I ended up with a slightly viscous white liquid. The zinc did suspend (stable) in the water, which is kinda unusual

Gotta be honest, was half expecting it to do something unusual, but it was completely uneventful. The solution also didn't feel any different than I would expect from water+salt+zinc oxide. I am working with non-nano zinc if the particle size makes any difference.

It is typical when adding Zechstein salts to water at high concentration (30%+ MgCl) that the viscosity of the mixture increases and it has an oily feeling ... that's why it is generally referred to as Magnesium Oil. How much MgCl did you add to make your solution and how much ZnO?

You would not notice anything with the naked eye ... the only way to tell what happened would be to do a chemical analysis, but that is just simply not worth the expense unless you really want to know.

Zaf · August 2019

I used equal parts magnesium and zinc. I'm not using natural salts, rather 100% magnesium chloride (not that that makes a difference when we're talking boyancy - just not sure if it makes a difference difference in chemical reaction... though I'd assume in this case it wouldn't).

I got the impression that the pH should drop though... and I'd think quite a lot. The point is mute though. At this point I think I'll just make two test batches: one with magnesium sulfate and zinc oxide, and one with magnesium chloride (without zinc)... see how I feel about both of them and go from there.

On the bright side... I spent awhile messing with the quantities and think I finally came up with something workable. The only thing left is to make them and test them... then move things around more if needed ?

Magnesium/MSM Cream - Preservatives & pH?

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