# Preferred Chelating Agents



## Sacto (Feb 9, 2018)

When it comes to using chelating agents, what are your preferences? I know some use EDTA others Sodium Citrate. Are there others you prefer to use? Also, why do you prefer one over the other? 

I have been using Citric Acid and Sodium Hydroxide to make my own Sodium Citrate.


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## earlene (Feb 9, 2018)

I use Tetrasodium EDTA because in combination with ROE, it is effective against DOS (per Dr. Kevin Dunn's testing).  

I have not tried Citric Acid, so cannot compare.

According to Kevin Dunn's experiments the combination of BHT and sodium citrate was more effective than EDTA + ROE, but when I made my decision it was based on a feeling at the time, that BHT sounded a bit less desirable than EDTA as an additive to my soaps.

Reference:  http://cavemanchemistry.com/DreadedOrangeSpot-Dunn.pdf  (skip to page 3, second column for the results)


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## IrishLass (Feb 9, 2018)

I use tetrasodium EDTA. I've never used sodium citrate, so I cannot compare. I chose to use EDTA simply because it's an ingredient I always have on hand as a part of my preservative system for my lotion formula. 

I started using it in my CP soap about 6 years ago or so when I learned it could also help lessen the build-up of soap scum from showering with my soap in our hard water (we have crazy hard water), and it has helped tremendously with that.

RE: DOS- I've only ever gotten DOS once or twice in all of my 12 years of soaping , but the fact that it helps with that, too, is a wonderful extra bonus to me.

Lastly, its unique preservative-boosting qualities are also a nice bonus to my liquid soap formulas that I make for myself and family, for which I have chosen to forego using a preservative. Although EDTA is not a preservative in and of itself (i.e. it doesn't have the ability to actively kill molds and bacteria), it does have the ability to weaken them by disrupting their digestive system so that it's hard for them to thrive.


IrishLass


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## BattleGnome (Feb 9, 2018)

I use citric acid. This decision was mostly made because I had purchased 10# of it on sale for bath bombs right before I fell in the CP rabbit hole then shoved it in the back of the cabinet. I think I’ve made 2 batches of bath bombs and probably have 9 pounds of citric acid left (even after I started using a chelator about a year ago)


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## cmzaha (Feb 9, 2018)

I use EDTA, because I was having trouble with citric acid crystallizing. on the outside of my soap


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## Sacto (Feb 9, 2018)

cmzaha said:


> I use EDTA, because I was having trouble with citric acid crystallizing. on the outside of my soap


I'm curious, what does it look like? (The crystallized citric acid that is.) Does it look like soda ash? Also, what percentage were you using?


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## neonstudy (Feb 12, 2018)

I just finished making soap with varying amounts of citric acid. I used 0, 1, 2 and 3% citric acid, and added extra lye to compensate as per blog posting by classic bells about citric acid. I was hoping that the 3% citric acid would be outrageous, and I'd have weird crystals, or blobby soap, or something, but it actually feels great and looks normal (no crystals). The 3% soap feels less squeaky than the others. I have to motivate myself to try something higher now, like 5 or 10% for comparison, although my old citric soaps will then be more than a month older than the new test. We'll see if I feel motivated or not. So anyways, as of right now, I am a fan of 3% citric acid.


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## gloopygloop (Feb 12, 2018)

neonstudy said:


> I just finished making soap with varying amounts of citric acid. I used 0, 1, 2 and 3% citric acid, and added extra lye to compensate as per blog posting by classic bells about citric acid. I was hoping that the 3% citric acid would be outrageous, and I'd have weird crystals, or blobby soap, or something, but it actually feels great and looks normal (no crystals). The 3% soap feels less squeaky than the others. I have to motivate myself to try something higher now, like 5 or 10% for comparison, although my old citric soaps will then be more than a month older than the new test. We'll see if I feel motivated or not. So anyways, as of right now, I am a fan of 3% citric acid.



Whoops not got to grips with this new format yet!
I now use Sodium Citrate where as before I was using Citric Acid neutralised with extra lye, have not used EDTA but may do in the future, the Citrate does help hugely with soap scum as did the Citric.


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## Steve85569 (Feb 12, 2018)

I use sodium citrate that I have reacted and dried slowly in the oven ( set on warm). It does take a bit to get it dissolved ( just wait a few seconds stirring) but I do not use more than 2% PPO. Sodium Citrate is a salt that really likes water and can soften soap for that reason. Soap can also only hold so much salt before it starts to produce "ash". Sometimes it's soda ash and sometimes the look can be sodium citrate, sodium acetate (vinegar for hardening), table salt etc...


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## Dahila (Feb 12, 2018)

I used CA then switched to sodium citrate, but the best results are when I use EDTA


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## gloopygloop (Feb 12, 2018)

I use SC @2% of total oil batch NOT 2% ppo and find it is working very well, not softening my soap and as I HP dont have any ash issues, it really helps a huge amount at reducing soap scum as I  live in a very hard water area. I shall be trying it with a CPOP to see what happens but interesting to hear the positives of EDTA.


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## Saffron (Feb 12, 2018)

I find handmade soaps with EDTA make my skin dry and rough. Has anyone else experienced that?


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## Shelldybop (Feb 13, 2018)

Hey, I'm new here. Been lurking for a while 

So I'm making bar soap for hardwater, and had planned on adding citric acid to hp with sf and scent instead of citrate... it seemed idiot proof... has anyone done this and had it work well? Are there any useful guides on how much to use? 

I know it depends on recipe, and ph testing after the cook is the way to go, but Im having trouble nailing down an exact ph for CA, and a formula for how much to use to get a 7 or 7.5 ph

Sorry if this has been covered elsewhere, I searched and couldn't find anything


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## shunt2011 (Feb 13, 2018)

Shelldybop said:


> Hey, I'm new here. Been lurking for a while
> 
> So I'm making bar soap for hardwater, and had planned on adding citric acid to hp with sf and scent instead of citrate... it seemed idiot proof... has anyone done this and had it work well? Are there any useful guides on how much to use?
> 
> ...



Hello and welcome!   PH testing is useless in soap.  You can't bring the ph down to 7-7.5.  it will not then be soap.  Soap's PH is generally 9-11.   Zap testing is all you need when making soap.  You want to know if there is any free lye.  For Citric Acid, you will need to add more lye to account for the lye the citric will take in.   DeeAnna has a great information here on all things soapy https://classicbells.com/soap/soapyStuff.html


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## cmzaha (Feb 13, 2018)

Sacto said:


> I'm curious, what does it look like? (The crystallized citric acid that is.) Does it look like soda ash? Also, what percentage were you using?


 Looks a lot like soda ash but you could feel it. My usage rate was 2% of my total batch weight


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## penelopejane (Feb 13, 2018)

Yes I agree. I don’t like the feel of the soap either. It makes a soap hard though. 
It’s not a “natural” product either but many people use it as not everyone cares about “natural”.



Saffron said:


> I find handmade soaps with EDTA make my skin dry and rough. Has anyone else experienced that?


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## cmzaha (Feb 13, 2018)

I have no issues with EDTA and no complaints from customers plus I find it much easier to use than citric acid with no crystallization on the outside of my soaps


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## Shelldybop (Feb 15, 2018)

shunt2011 said:


> Hello and welcome!   PH testing is useless in soap.  You can't bring the ph down to 7-7.5.  it will not then be soap.  Soap's PH is generally 9-11.   Zap testing is all you need when making soap.  You want to know if there is any free lye.  For Citric Acid, you will need to add more lye to account for the lye the citric will take in.   DeeAnna has a great information here on all things soapy https://classicbells.com/soap/soapyStuff.html



Thanks for the link, some very useful info 

I'm interested in citric acid as a chelator for magnesium/calcium in hardwater, so looking to add it after the cook in HP and not into the soap while it is still caustic. 

Ive been looking at its use in lotions ect., but cant seem to find consistent guides on how much is ok to use. 

Would really appreciate any shared experience!


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## DeeAnna (Feb 15, 2018)

_"...I'm interested in citric acid as a chelator for magnesium/calcium in hardwater, so looking to add it after the cook in HP and not into the soap while it is still caustic...."_

It isn't citric acid that is the chelator. The chelator is citrate, meaning the dissociated salt of sodium hydroxide and citric acid.

You don't want citric acid to stay in its acid form, even if you could make it follow your orders. You want the acid to dissociate (break apart) into citrate to function  properly as a chelator.

Citric acid WILL dissociate in an alkaline (high pH) environment, such as in soap, no matter when you add the acid. The result is that citric acid will raise the superfat unless you add the extra NaOH to compensate for the dissociation of the citric acid.

_"...cant seem to find consistent guides on how much is ok to use..."_

You won't find consistent guidelines for how much to use, because there is no one right answer -- there is a range of typical dosages for its use as a chelator in soap. More: https://classicbells.com/soap/citricAcid.html

If you're looking at its use in lotions and trying to extrapolate that to its use in soap, this is an apples and oranges comparison.


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## Nanditasr (Feb 17, 2018)

DeeAnna said:


> You won't find consistent guidelines for how much to use, because there is no one right answer -- there is a range of typical dosages for its use as a chelator in soap. More: https://classicbells.com/soap/citricAcid.html



Thanks; this is most useful. I used 10 grams per kilo of oil (plus appropriate extra lye), and it worked like a charm. No more scum in my bath water, and it made my hair more shiny! I have a couple of questions on a related note:

1. Just for curiosity, I did my dishes with this soap. Definitely less scum in the sink than with my earlier soaps. (I deliberately used soaps with the same SF %, for a fair comparison.) But not totally gone -- I see dry white droplets on my stainless steel dishes -- not as much as before, but it's still there. Therefore, *should I up the citric acid until I get to the stage of no droplets on the dishes? Will it be harsh on the hands *if I do this?

2. Suppose I use 20 grams per kilo of oil, for a bath soap (formulating it for harder water). *If I then use this soap in softer water, will there be a problem?* Will this feel stripping?


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## DeeAnna (Feb 17, 2018)

_"...should I up the citric acid until I get to the stage of no droplets on the dishes?..."_

Even a whole house water softener can't remove all the hard water minerals in water. It is totally unrealistic to expect a tiny bit of chelator in a bar of soap or in a squirt of liquid soap to solve the problem, especially when you're talking about treating water used to wash dishes and clothes.

On top of that, there are consequences to the quality of the soap if you try to load it with an excess of an additive like this. At about 3% citric acid or more, the soap will begin to feel rubbery and citrate salt crystals will form a white efflorescence on the surface of the soap. 

_"...Will it be harsh on the hands... If I then use this soap in softer water, will there be a problem? Will this feel stripping?..."_

I use EDTA, not citrate, but I've not noticed anything like that. You seem to be thinking the use of a chelator will affect the mildness or harshness of the soap itself. You need to look at your basic soap recipe for whether the soap will be harsh to the skin or not. A harsh soap will be harsh whether you use it in hard water or soft. A gentle soap will be gentle regardless of the water.


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## Nanditasr (Feb 17, 2018)

DeeAnna said:


> You seem to be thinking the use of a chelator will affect the mildness or harshness of the soap itself. You need to look at your basic soap recipe for whether the soap will be harsh to the skin or not.


Thanks; yes, I _was_ indeed worried that the chelator might affect the mildness or harshness. Actually, I am very happy with the recipe of the soap. Now that you've clarified this, I'll probably tweak it with just a tad more citric acid (maybe increase the 1% to 1.5%).


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## Shelldybop (Feb 21, 2018)

So in the course of my weird and wonderful experiments I seem to have stumbled  across something odd... soaps with CA stay wet for longer. Not as in soft while curing, but wet while drying between uses...

For the s***s and giggles, and because I had some lye that I had mixed wrong and didn't want to waste, I made a 20% citrate bar. I HPd with a very conditioning high linoleic recipe and a little rose clay (I am colour coding my endeavours), while that's a pretty extreme % it is waaay more drying than I expected and also still has that wet feel.

Just thought Id share!


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## Nanditasr (Feb 21, 2018)

Shelldybop said:


> ...soaps with CA stay wet for longer. Not as in soft while curing, but wet while drying between uses...


Interesting! I don't think I've had that experience.


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## BattleGnome (Feb 21, 2018)

Shelldybop said:


> I HPd with a very conditioning high linoleic recipe and a little rose clay (I am colour coding my endeavours), while that's a pretty extreme % it is waaay more drying than I expected and also still has that wet feel.



Interesting on the wetness observation. I may eventually test the comparison.

I just wanted to note that the clay could also be causing the dryness. Have you tested other (more familiar) recipes with and without the clay to get a feel for how your skin interacts?


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## Shelldybop (Feb 22, 2018)

Steve85569 said:


> Sodium Citrate is a salt that really likes water and can soften soap for that reason. ...(vinegar for hardening...



Yup, that seems to be the reason for staying wet. Please tell me more about vinegar for hardening?



BattleGnome said:


> I just wanted to note that the clay could also be causing the dryness.


Ya, Ive used clays before. Probably more due to there being 20% extra salt!


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## SudsanSoaps (Feb 22, 2018)

I used citric acid at 2% because I have super hard water. Seemed liked it made my soap never get very hard so I add either vinegar or lactic acid also.


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## bumbleklutz (Feb 22, 2018)

I've used both citric acid (reacted with extra NaOH to form sodium citrate) and Tetrasodium EDTA as chelating agents in bar soap to combat my extra hard water.  For me, Tetrasodium EDTA wins hands down.  Not only does it help to combat DOS in combination with ROE, but by binding up some of the hard water ions it really boosts lather and reduces scum more effectively than sodium citrate; at least for me.


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## Nanditasr (Feb 22, 2018)

SudsanSoaps said:


> I used citric acid at 2% because I have super hard water. Seemed liked it made my soap never get very hard so I add either vinegar or lactic acid also.


I've done the same a couple of days ago! Waiting to see what happens.


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## earlene (Feb 22, 2018)

Shelldybop said:


> Please tell me more about vinegar for hardening?



There are several threads here on the forum about using vinegar in soap.  I'll link one or two I have saved, but if you use the search feature you can find more.  Also within threads, there are often links to more information on the topic.

How to use vinegar to harden your soap

Oil & Vinegar - Sodium Acetate in Soap experiment

Testing vinegar/sodium acetate in soap - phase II


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## Steve85569 (Feb 22, 2018)

I now use reacted vinegar for half of my liquid in making soap. When I get a new bottle of vinegar I react it with lye using the formula in the first post that earlene posted. That takes the 5% acetic acid in the vinegar and creates a solution of water and sodium acetate that is at 4.8%. Using half gives me sodium acetate at 2.4% which more than compensates for the sodium citrate I use as the chelator.
Since the sodium acetate is a hardening salt ( as opposed to sodium citrate) it helps create crystaline structures within the soap matrix resulting in a harder, longer lasting bar of soap.

Now mind you that's working from my memory so I could be wrong on just how it works to make a harder bar. Someone with more knowledge of chemistry will correct me and set the facts in place for us if I am leading you astray.


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## lsg (Mar 23, 2018)

I have to say thank you to those of you who recommeded EDTA for liquid soap.  I tried it and am now using my glycerin liquid soap for hand washing dishes.  Before adding the EDTA, I had a problem using liquid soap with our hard water.  Any more recommendations willl be greatly appreciated.


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## DeeAnna (Jun 27, 2018)

Shelldybop said:


> ...soaps with CA stay wet for longer. Not as in soft while curing, but wet while drying between uses... I made a 20% citrate bar ... [it] still has that wet feel....



I just read the last several posts in this thread and I wanted to respond to this one. 

When combined with NaOH, citric acid makes citrate. Citrate is a type of salt, as chemists define salts, and salts are often hygroscopic (chemicals that attract and hold water).  

I get the impression you were expecting this soap to act like a normal soap -- one made with little or no added salts -- when it's actually closer to a salt or spa bar.


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## bristles (Jul 14, 2018)

sorry to bump an older thread but when do you add the EDTA or sodium citrate when making soap? ill be making hot process soap and want to use this for the hard water where i live


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## Dahila (Jul 14, 2018)

I add it to water just before lye,    You asked about difference with EDTA and Sodium Citrate,  I think my soaps with EDTA lather better.  I still have some with Sodium Citrate.  
BTW Disodium EDTA is much better for lotions cause is lower ph Disodium have ph of 5,  So I switched for lotions to Disodium EDTA (Irishlass   )


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