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Magnesium/MSM Cream - Preservatives & pH?
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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.
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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 -
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.
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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? -
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.
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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) . -
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. -
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. -
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. -
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! -
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?).
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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.
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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)
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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… :smiley:
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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?). ?
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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***)
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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!).
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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 unusualGotta 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.
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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 ?
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