Sodium Gluconate (SG) &/ Citric Acid in Brine Soap to deeply clean oil & dirt

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Garden Gives Me Joy

Well-Known Member
Jan 25, 2020
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United States
My #1 aim is to maintain the apparently deep cleansing and oil fighting properties of magnesium, calcium, and potassium in BRINE soap. However, do these same wonderful minerals promote rancidity and soap scum? Furthermore, do chelators like sodium citrate (derived from adding citric acid) and or sodium gluconate / SG counteract any potentially beneficial effect that these minerals offer?

On a side note, one reason I worry about rancidity is because my environment is tropical and hot which, from my understanding accelerates the onset of rancidity. So, on the basis of chelation being necessary, what are my best options alone or in combination re usage rates (ie as a percentage of oil wgt) between the following? How do soapers combine these and to what extent?

  • Citric acid (to make sodium citrate).
  • SG. I gather usually used at 0.1% to 1.3% of oils wgt (1.3% is based on advice from compliance assessors to Norway-based @Bubble Agent).
  • ROE is NOT available to me (because Customs restricts its entry into my current location).

My secondary considerations re SG alone or with citric acid is bubbles.
  • Since salt reduces lather, I want to improve lather if possible. FYI, my water is relatively soft. Since SG is a surfactant, can it surpass citric acid, even if to create more slippery bubbles?
  • My non-soap research suggests that SG is a surfactant and conditioning. I am confused to see those 2 concepts relate to a single ingredient. Are these properties noticeable in soap?
Sorry if the following might sound a bit harsh at times, but in my impression we have to clear some misconceptions first.

apparently deep cleansing and oil fighting properties of magnesium, calcium
This is the first time I read that soap scum (Ca and Mg salts of fatty acids) is reported to help dissolve oils. My observations so far were that they ruin lather, and are much more sticky and nasty than oils themselves, particularly on the skin. I'm curious: is this your anecdotal experience, and/or can you refer to other sources that support that soap scum is beneficial to grease dissolving performance? I'm not so much into brine soaps, so it might well be the case that I just don't know this.

The only difference between potassium and sodium soaps is the hardness/solubility, i. e. the willingness of soap molecules to disperse into water (K → liquid soap) or stay together until you rub the molecules apart (Na → bar soap). A few % of K cannot change properties of soap much, particularly not in brine soap (where you have much more Na than from NaOH alone).
Just for curiosity: where does you potassium come from? I've never heard of tap water that high in potassium that it would make any difference.

Regarding chelators and DOS-promoting metals: keep in mind that rancidity is something that happens within the soap, and DOS are only the visible/smelling after-effects. The relevant trace metals to be scavenged by the chelator are those that are inside the soap batter at soapmaking time. Not those that are spilled on the outside and washed away with each usage.

Citrate and gluconate are ineffective towards potassium, but then again, you don't need to protect against it (it doesn't promote DOS, otherwise LS makers would be in high danger!).

SG is a surfactant
Alone from the molecule structure (no hydrophobic “tail”), I doubt this is the case. I might be wrong – but then why doesn't everyone just use pure SG for cleaning, and skip all the difficult, dangerous and expensive soapmaking steps with oils, lye, etc.?
If any, SG is a sugar and might promote lather similar to how table sugar or sorbitol act (I don't have experience with SG, though).
Both SG and citrate do a decent job in complexing DOS-troublesome trace metals, as well as scum-troublesome alkaline earth metal ions. For the former task, minute quantities suffice, at which it makes zero difference for the soap performance anyway. And the latter task (soap scum prevention) might not be relevant for you at all, given you have soft water.

to deeply clean oil & dirt
more slippery bubbles
My impression is that you are unhappy with your recipe for reasons that actually aren't related to chelators at all. It's a bit difficult to get your point without knowing where you stand, and with that vague description of your issues.

Actually, for cleaning with soap, water can't be soft enough, but on the other hand, soft water can amplify issues with too generous superfat, cause slippery haptics, and difficulties to wash the soap off the skin.

What is your oil blend, superfat, and additives (salt/brine, exfoliants)? Do use the soap for washing dirty hands/body (soap cloth?), or dishes/tools/laundry?
Oh wow, I definitely see how I did not write the question correctly. For starters, indeed, "deep cleansing and oil fighting properties" do not come from 'magnesium, calcium, and potassium.' I should have said that my impression is that sea salt water in brine soap can help to deeply cleanse the skin of dirt and excess oil.

Re the magnesium, calcium and potassium, I assumed that their presence in sea salt was responsible for the positive difference sea salt seems to have made for oily skin friends (when compared with soaps without sea sa;t brine). That should have been a question because I am uncertain.

I considered chelation because I fear that the salt can make it easier for my soap to develop soap scum and rancidity. However, I worried that perhaps chelation would target those same minerals. that possibly added positive benefits to my brine soaps. Maybe that is a wrong assumption?! I was therefore worried about whether I lwould lose some of the extra punch I get from brine when I add chelators. I really do not understand the science behind chelation and had hoped that someone could enlighten me regarding whether my fears are unfounded. I just found a supplier of SG and was hoping to get some advice before placing my first order.
I really think its just the salt ... that help oily skin.
Yes that is what I thought.

However, do chelators like SG and sodium citrate minimize the salt's ability to help oily skin?

(... ie considering the types of mineral supposedly present in unrefined SEA salt (that very plain table salt /NaCl2 does not have) ... and those that chelators attract).
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However, do chelators like SG and sodium citrate minimize the salt's ability to help oily skin?

I really don't the answer to this but I suspect it won't affect the salt enough to minimize it.
Best way to find this out is make a small batch with your chelators and see how it is.

I make salt bars, not brine bars for oily skin and soap scum isn't a issue.
I have used Sodium Gluconate for many years now, and include it in mostly every soap I make (to counteract hard water issues)

I have made a couple of brine soaps, and a couple of regular salt bars. I have used up the last salt bar I made, and that one was about 4 or 5 years old (made a batch for just me) I have not noticed any issues whatsoever in the feel of the soap it self, and it contained at least 1% SG. I can not speak for the chemistry though, if something is happening "behind the curtain" that I can not see or feel.

But since I have used it successfully all this time without any issues I will still use it.

I know this wasn`t a chemistry type answer to your question, but at least I can tell you about my empirical data:)

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