# Citric acid as a chelator



## coffeetime

I live in an area with very hard water, and I wondered if it is advisable to use a little citric acid in with the KOH? Would that act as a chelator for hard water?  
I searched the liquid soap board but the only references I found were for using CA to neutralize.
I did look up potassium citrate, as I assume that is what would be formed (?) and it doesn't indicate chelation at all, just alkalinizing, so I am probably completely off base. :-?  Is there any way to reduce soap scum with liquid soap?


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## The Efficacious Gentleman

I think it does, but I am not sure.

If in doubt, could you whip up a batch of sodium citrate using the baking powder method (or using NaOH if you want) and add in some Sodium Citrate rather than citric acid?


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## DeeAnna

You can add citric acid to form citrate as a hard water chelator. In a KOH soap you'd be making potassium citrate, but that's not the point really. It's the citrate ion that is the chelator, not the sodium citrate or potassium citrate molecule. 

The liquid soapers don't discuss this because their mindset is not focused on that aspect of what citrate can do. They are only looking at citric acid as a neutralization agent for excess lye, as you noted. But when they do neutralize with citric acid, they are inadvertently also making citrate -- they just don't know it.

If you use citric acid in the sense of its being a chelator and not a neutralizer, then add the extra lye needed for the citric acid to react with -- 
10 g citric acid neutralizes 6.24 g NaOH. 
10 g citric acid neutralizes 8.42 g KOH.

ETA: Wikipedia has a little bit about citrate's ability to chelate (bind up) metal ions such as calcium to prevent blood clotting and to descale boilers. These applications aren't about soap, I agree, but the principle is the same. https://en.wikipedia.org/wiki/Trisodium_citrate


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## coffeetime

Thank you so much, DeeAnna! That is exactly the info I was hoping someone would have. That's awesome. I'm hoping to make myself a test shampoo and I think the citrate would help with the horrible buildup I get with bar soap (which I haven't tried adding citric acid to yet). So many projects, so little time...


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## rain_darned_owl

Normally I have an aha moment when I read DeeAnna's comments, but I am a bit lost here (note I haven't made liquid soap with KOH before):

"If you use citric acid in the sense of its being a chelator and not a  neutralizer, then add the extra lye needed for the citric acid to react  with -- 
10 g citric acid neutralizes 6.24 g NaOH. 
10 g citric acid neutralizes 8.42 g KOH."

I am making bars of soap (NaOH) so are you saying to ...
1. add extra lye to compensate for adding citric acid as a chelator?  or,
2. if your recipe calls for 6.24g of NaOH then you can add 10g citric acid as a chelator (and if you have more or less NaOH then do the math to figure out the amount of citric acid)


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## ngian

Saponifier said:


> I use citric acid as a chelator in all my LS and I've noticed less scum in the sink.  Definitely give it a try.



If you have sodium citrate powder that doesn't need extra NaOH, when would you add it? While you are making the paste or at the dilution phase?


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## Susie

ngian said:


> If you have sodium citrate powder that doesn't need extra NaOH, when would you add it? While you are making the paste or at the dilution phase?



You add it at the paste phase.


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## Susie

rain_darned_owl said:


> Normally I have an aha moment when I read DeeAnna's comments, but I am a bit lost here (note I haven't made liquid soap with KOH before):
> 
> "If you use citric acid in the sense of its being a chelator and not a  neutralizer, then add the extra lye needed for the citric acid to react  with --
> 10 g citric acid neutralizes 6.24 g NaOH.
> 10 g citric acid neutralizes 8.42 g KOH."
> 
> I am making bars of soap (NaOH) so are you saying to ...
> 1. add extra lye to compensate for adding citric acid as a chelator?  or,
> 2. if your recipe calls for 6.24g of NaOH then you can add 10g citric acid as a chelator (and if you have more or less NaOH then do the math to figure out the amount of citric acid)



1.  You add extra lye to compensate for the citric acid.  You are making bars, so you would add 6.24 g of NaOH for each 10 g citric acid.


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## galaxyMLP

Wouldn't sodium citrate be a problem since we are making potassium based soap? I would think it would act a bit like adding table salt where some of the soap (not a ton, but some) will salt out. 

Susie, do you find after adding the SC your soap gets cloudier or it forms a separate layer?


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## Susie

I have super soft water, so I do not personally use SC or CA.  

However, since SC is not acidic, it will not affect the pH of your product.  That is the primary benefit of using that rather than CA.  No fancy fiddling with math, or worry about soap separating. You aren't going to use a great deal of it to worry about it salting out your soap.

And there is no reason to worry about it being a problem with KOH based soap.  I have made liquid soap with up to 40% NaOH with no problem whatsoever.  Again, the amount you are going to use is so small.

https://en.wikipedia.org/wiki/Sodium_citrate


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## galaxyMLP

Lucky you with the soft water! Sorry, I thought with the way that you worded your post that you did use it in your soap. My bad!

I understand that it wont need any neutralization but, I'm wondering if since its sodium citrate and not potassium citrate if it makes some sodium soap form and makes the soap cloudy or separates the newly formed sodium based soap from the water soluble potassium based soap. I don't think it would take alot to do that. I'll have to test it tomorrow!!


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## DeeAnna

Rain -- here's an example that I hope clears things up for you. Say you have a recipe that calls for 100 g of KOH to saponify your fats. And you decide to also add 10 grams of citric acid to make citrate because you have hard water issues. To get that citrate made, the citric acid is going to use up some lye. You don't want it to use lye that is needed for saponification, so you will want to add extra KOH. The rule is 10 g citric acid neutralizes 8.42 g KOH, so you would need to use an extra 8.42 g KOH in this recipe -- this KOH is in addition to the KOH for saponification.

Total KOH = (KOH for saponification) + (KOH for the citric acid) = 100 g + 8.42 g = 108.42 g

***

Galaxy -- You have a valid point!


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## Susie

galaxyMLP said:


> Lucky you with the soft water! Sorry, I thought with the way that you worded your post that you did use it in your soap. My bad!
> 
> I understand that it wont need any neutralization but, I'm wondering if since its sodium citrate and not potassium citrate if it makes some sodium soap form and makes the soap cloudy or separates the newly formed sodium based soap from the water soluble potassium based soap. I don't think it would take alot to do that. I'll have to test it tomorrow!!



I have used KOH 60%:NaOH 40% recipes with no loss of clarity.  If this is not what you mean by "sodium soap", then I apologize for misunderstanding, and could you please clarify?


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## galaxyMLP

Really?? Very interesting!

 I would've thought that the sodium soap would separate or at least make it get cloudy but it makes sense now. Both stay emulsified together. Thanks Susie!


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## DeeAnna

I agree with Susie that sodium hydroxide doesn't necessarily cause soap to be cloudy or opaque. It's more the fats used (stearic, palmitic) and the solvents (water, alcohol, sugar, glycols, etc.) that affect clarity. Couple of examples -- I recently dissolved a grated up bar of olive oil (castile) soap in distilled water. I wanted to make a gel soap to use when wet-felting wool. I had made the original soap using only 100% NaOH, olive, and distilled water. The resulting gel isn't liquid -- it's more like firm Jello dessert -- but it is as clear as if it was a KOH-olive-water soap. The original Pears soap was an NaOH soap that was then dissolved in ethanol. The ethanol was allowed to slowly evaporate off, leaving a transparent soap behind.

But there's another aspect to the issue Galaxy wrote. The sodium may not be causing the problem; the citrate may be. I wrote on September 14th in the "Sodium citrate from baking soda and citric acid" thread about the same issue Galaxy is referring to -- adding sodium citrate to diluted LS DOES cloud the soap and cause separation. I don't have an answer to this issue, and I'm glad to finally hear I'm not the only one with the problem. 

Here's what I wrote in Post 100 of that thread:

"I was wanting to use my homemade citrate to see how citrate controls soap scum created by mixing hard water from our well with my liquid soap. I wanted to add these results to the thread I started here: http://www.soapmakingforum.com/showthread.php?t=52456. Problem is, when I added the citrate to the water and soap solution, the citrate "broke" the soap so I ended up with scummy water that had a layer of fatty acid on the surface. 

"Thinking perhaps I had an excess of citric acid still left in the solution, I added a bit extra baking powder to ensure the acid was fully reacted to citrate. Tried the test again. Same results. Added a bit of citrate solution to just the liquid soap -- no added water -- and the mixture of citrate and the (originally transparent) LS turned an opaque white.

"I'm stumped. My understanding has been that citrate works pretty well to chelate metals and reduce soap scum, and I haven't been hearing people complain about citrate "breaking" their soap. You other soapy chemistry geeks out there -- what am I missing? Suggestions and thoughts are most appreciated."

Source: http://www.soapmakingforum.com/showpost.php?p=544929&postcount=100

Edited 7 June 2016 to add -- I found the reason why my LS was turning white and separating when I added sodium citrate. I had made this citrate by reacting citric acid and baking soda to make a citrate solution. This solution also had excess baking soda in it, and it was the soda that was breaking down the soap. Sodium citrate without any excess baking soda (either bought commercially or made more carefully) works just fine -- no cloudiness and no separation.


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## galaxyMLP

So then maybe in this case it is acting like regular salt is when you add it to LS and some of it "salts out" at the top? I've neutralized my SC so I'll try it with mine tonight and see what happens. I made some paste the other day (not perfectly clear when diluted but, I'll be able to tell once I add the SC if there are any differences.)

Dee, we should also try making potassium citrate by the extra lye method and seeing if we get that same separation result If I get the same separation with my SC tonight. 

I'll try tonight and report back. Would you like me to do it on the other thread or this one?

ETA: Ill try it w/ my castile recipe and also my new paste w/ palm, olive, shea and castor (its a little cloudy but not bad)


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## DeeAnna

Galaxy -- for me, continuing this discussion here in this thread is fine.

***
Geek Alert -- seriously nerdy chemistry stuff is coming up next! 
***

Galaxy -- Some thoughts....

Could the baking soda and citric acid reaction be incomplete in that we don't have TRIsodium citrate, but instead a mix of tri-, mono-, and di-sodium citrate? In that case, the mono- and di- would act as weak acids in the diluted LS, similar to adding citric acid.

The pH of trisodium citrate ranges from 7.5 to 9.0 (0.1 M in H2O, 25°C). The pKa values for citric acid and its ionic forms are 3.138, 4.76, 6.401.

Or could our addition of citrate to the diluted soap, with its relatively low pH, be what's messing things up? Maybe we need to be adding the sodium citrate to the highly alkaline soap batter to force it to dissociate fully to Citrate 3- ion?

I'm a little outta my league here, to be honest, but this is what I'm currently wondering about. Any thoughts???


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## coffeetime

I certainly don't mind the discussion occurring in this thread. It's fascinating!


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## DeeAnna

Thanks, Coffeetime. It's your thread and I would respect your wishes if you don't care for the direction this sidetrack is going.


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## galaxyMLP

You know, I thought about that briefly. That's why I kept adding baking soda until it didn't fizz any more and the solution was around a pH of 8. I'd like to try it with adding some more baking soda to reach a pH of about 10 and see if that makes a difference as well.

If we've got some mono and di sodium citrate that could definitely explain the cloudiness. 

I'll try 3 things tonight then:

1. castile soap paste diluted w/ 2% added SC 
2. palm/olive/shea/castor soap paste diluted w/ 2% added SC
3. castile diluted w/ 2% SC w/ added BS to make pH ~10
4. palm/olive/shea/castor diluted w/ 2% SC w/ added BS to make pH ~10

This will tell us if its the SC itself or if its the pH/the way we are making the SC. I want to try with both of my recipes to see if it makes a difference with the types of fatty acids too.

If none of those experiments results in a clear/unseparated/unchaged soap, I will make potassium citrate with my next liquid soap paste by the extra lye method.

ETA: Thank you coffeetime for allowing us to continue on your thread! We've hijacked it...


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## TeresaT

I don't understand 95% of what you're talking about, but I love the geek talk.  I love the fact that you are so excited about the science of your hobby and not just the hobby itself.  The science never gets boring, does it?  AND you are so willing to share your knowledge and dumb it down for the likes of me.  If we were at a coffee shop, I could just picture you excitedly going at it and my head going back and forth like a tennis tournament. It reminds me of a friend and me with "fiber talk" at gatherings.


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## The Efficacious Gentleman

See now, swirling and colours and all that jazz I can take or leave - but this sort of thing gets my eyebrows raised and the pipe removed from my mouth in interest.


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## DeeAnna

Well, I'm glad Galaxy and I are entertaining y'all.  

I feel rather clueless at the moment, and that's not especially comfortable place for me, but feeling unsure is all part of the process of solving problems and learning stuff. I really hope something will come of this group discussion and experimentation that will benefit all of us.


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## galaxyMLP

You all are making me want to get home as soon as possible to try this but I know I cant get to it till around 8:30 pm tonight (6 1/2 hours away!)


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## Susie

I am not much into the swirling and such, either.  But I am following every word here.  I am off today and doing house/yard work, but SMF is up on the computer so I can catch up every time I come inside.


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## galaxyMLP

My experiments are sitting now. 

I don't see a difference or separation in the palm/olive recipe ones so far. I've got a control w/ just DI water, one  with just SC added, and one with BS and SC. I added the SC at 2% or the soap paste. For the one with added BS, I added BS to the water w/ SC to reach a pH of 10 on my test strips. These 3 are still diluting.

I already had diluted Castile so I thought I'd give it a go.  I made a boo boo and added the SC at 2% of the diluted soap! The one with SC in it got SUPER thick, gloppy and gel like. The one with BS and SC stayed liquid but was completely cloudy. This was a Castile diluted for a foam pump @ 1:6. What was very interesting is that the gel like Castile soap lathers amazingly and leaves hands free of that hard water scum feeling. Might actually be a good finding in this case. 

I'll report back about the other soaps that are diluting tomorrow.


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## DeeAnna

Thanks, Galaxy -- you're amazing!


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## Saponista

I use a solution of sodium citrate to thicken my liquid soap. I use it instead of salt as I figured it would add some chelation. Unfortunately as it was only for me I didn't really measure it, I diluted some (a few tbsp) in distilled water then added it but by bit until the soap was at the consistency I wanted. It didn't cause any cloudiness or separation.


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## DeeAnna

"... I made a boo boo and added the SC at 2% of the diluted soap! The one with SC in it got SUPER thick, gloppy and gel like...."

That's pretty much what I'm seeing, Galaxy. The SC definitely thickens the diluted soap. Eventually the gel will turn opaque white with enough SC. If you put this thickened soap into an excess of water (as if you were going to wash dishes), the water-soap solution will show separation as well, if my experience is any indication. 

My thought is the white color change is the soap is breaking down in response to the added SC. That would be the downside to using SC to thicken liquid soap vs. table salt (NaCl). Table salt won't cause this breakdown. 

Much different outcome compared with adding an excess of EDTA.


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## ngian

DeeAnna said:


> "... I made a boo boo and added the SC at 2% of  the diluted soap! The one with SC in it got SUPER thick, gloppy and gel  like...."
> 
> That's pretty much what I'm seeing, Galaxy. The SC definitely thickens  the diluted soap. Eventually the gel will turn opaque white with enough  SC. If you put this thickened soap into an excess of water (as if you  were going to wash dishes), the water-soap solution will show separation  as well, if my experience is any indication.
> 
> My thought is the white color change is the soap is breaking down in  response to the added SC. That would be the downside to using SC to  thicken liquid soap vs. table salt (NaCl). Table salt won't cause this  breakdown.



Well it must be something in the way that the SC is made with BS that makes it cloudy. Maybe impurities in BS or some CA leftovers...

Anyway I had the same experience with Saponista. I did try to dilute my one year old soap paste (was kept in the refrigerator all the time) with store bought SC 4%, EDTA 0,5% and EDTA 1% without any cloudiness problem. Unfortunately I didn't make a dilution without any chelating agents  as a control sample just for comparison. 







The paste was:
(65% Olive, 25% Coconut, 10% Castor, 3% Lye Discount)
KOH 3:1 (ratio of water/glycerin to KOH)
and the water for dilution was 80% of the paste's weight.

[ame]https://www.youtube.com/watch?v=QXpMyM4iMS4[/ame]

It seems that Sodium Citrate apart from being a chelating agent, it can also build up viscosity. I tried all three of them and they produced really nice bubbles, but the one with SC has also that perfect honey-like viscosity! 

I need to make a new liquid soap so as to test Sodium Chloride vs Sodium Citrate and their affect to viscosity and bubbles...


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## DeeAnna

"...it must be something in the way that the SC is made with BS that makes it cloudy..."

You may indeed be right, Nikos. I thought of that too, but didn't have commercial sodium citrate to compare with the homemade. I'm glad you shared your results!


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## galaxyMLP

I think both of you are right about the baking soda+ SC

I think my explanation wasn't clear. My results were as follows (I'm working from memory after reading my old post):

Homemade SC only (from baking soda and CA)- clear, thickened soap, no noticeable lather reduction. 

Homemade SC plus additional baking soda added- Cloudy and separated. The mix was also very low viscosity.

So even with my homemade SC, as long as additional baking soda is not added, it should act as you saw with commercial SC and work as a thickener. 

I also just tried it last week with some commercial SC and it worked quite well.


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## DeeAnna

So it sounds like the culprit is excess baking soda causing the soap to dissociate. Makes sense.


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## KristaY

So I'm trying to boil all this amazing chemisty down to the nuts and bolts. Anyone who can correct any errors and answer any questions, please do so.

1. By using sodium citrate (as opposed to citric acid) no extra KOH or NaOH is needed. The pH of trisodium citrate is 7.5-9.0 so there's no worry of "breaking" the paste by accidentally lowering the pH too much. Plus, a small percentage is used so final pH shouldn't be a lot lower anyway?

2. Sodium citrate was used by ngian at 4% paste weight, galaxy at 2% paste weight so it was added during the dilution phase. Is the difference just in personal preference based on water quality in the home, viscosity desired in the final soap, a combo of the 2 or other factors?

3. Is it safe to assume the water needed for dilution was measured out, SC dissolved in that, then the whole added to the paste? What if I start at 2% SC but decide I want to add more. Will it need to be dissolved into water before adding to the diluted soap? I couldn't find a dilution ratio when I did a quick search so don't know how much water it takes to fully dissolve SC.

4. I know sodium citrate and citric acid can be purchased through many soap supply sites but did a google search for fun and the majority of the results are in the food industry. So is food grade SC and what is used in soap making the same purity?

5. Another topic included in this thread: Susie stated she's used up to 40% NaOH + 60% KOH to make LS paste. Why is that? What does the combo of hydroxides bring to the LS party?

I apologize if some of this was covered and I missed it but I'm just trying to get a clearer picture in my head. Thanks to any and all for help!


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## Susie

KristaY said:


> 5. Another topic included in this thread: Susie stated she's used up to 40% NaOH + 60% KOH to make LS paste. Why is that? What does the combo of hydroxides bring to the LS party?
> 
> I apologize if some of this was covered and I missed it but I'm just trying to get a clearer picture in my head. Thanks to any and all for help!



People mistakenly think that you can get thicker liquid soap by adding NaOH to the KOH when you make the paste.  You can't.


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## ngian

KristaY said:


> 2. Sodium citrate was used by ngian at 4% paste weight, ...



I used SC 4% of the final liquid soap weight (paste & water). In the specific experiment, the weight of the paste was 89gr so I added ~71gr water (80% of paste weight) and that made a total of 160gr. 4% SC is 6,4gr so that was the amount that I diluted in 71gr of water prior inserting it into the paste.

Generally I account the % of each additive as follows:

*In liquid soaps (KOH):* % of the total weight of paste and water used for dilution, as water will remain whole in the product when it will be used.
*In bar soaps (NaOH):* % of the weight of oils only, as part of the water in a recipe will evaporate by the time of a full cure.

That's my logic...


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## KristaY

Susie said:


> People mistakenly think that you can get thicker liquid soap by adding NaOH to the KOH when you make the paste.  You can't.



Good to know! I had a feeling that might be the thinking behind it. Other than not getting a thicker LS, did you notice a difference in the soap itself? Different lather, different viscosity, different ratio of water needed for dilution, etc?



ngian said:


> I used SC 4% of the final liquid soap weight (paste & water). In the specific experiment, the weight of the paste was 89gr so I added ~71gr water (80% of paste weight) and that made a total of 160gr. 4% SC is 6,4gr so that was the amount that I diluted in 71gr of water prior inserting it into the paste.
> 
> Generally I account the % of each additive as follows:
> 
> *In liquid soaps (KOH):* % of the total weight of paste and water used for dilution, as water will remain whole in the product when it will be used.
> *In bar soaps (NaOH):* % of the weight of oils only, as part of the water in a recipe will evaporate by the time of a full cure.
> 
> That's my logic...



Thanks ngian! Now I understand the direction and method you used. Since I never know exactly how much water it's going to take to dilute the paste, I guess I'll have to make an educated guess. Here's another thought I just had: did you add any EO or FO to your diluted LS? If so, did it behave any differently than batches without SC? Also, I use PS80 mixed with EO/FO when scenting. Will the SC interfere with that in any way?


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## ngian

KristaY said:


> did you add any EO or FO to your diluted LS? If so, did it behave any differently than batches without SC?



I will try and add some EO in the honey-like SC liquid soap and see how it will behave. As far as I know from my very little experience on the matter, some EOs affect a little on the viscosity of  LSs.


What I'm also thinking right now is that maybe in bar soaps (with NaOH) SC will act also as a hardening agent similar with salt, so salt (or any other sodium eg. sodium lactate) is not needed if we want a hard bar.

Although we are in a LS thread, now that I'm thinking about it in a wider perspective I guess the following are correct for a soap bar:

*Sodium Chloride (salt):* gives only a hard bar (and maybe cuts down some bubbles because of its physical hardness)
*Sodium Lactate:* gives a hard bar (and maybe adds a few bubbles)
*Sodium Citrate:* gives a hard bar and acts as a chelating agent
*Sodium Acetate:* gives only a hard bar (topofmurrayhill maybe can tell us if the soap with sodium acetate cuts down the bubbles, and it is because of the physical hardness of the bar that needs more abrasion to produce the same amount of lather).

In the world of LS I guess the above are true too, but instead of "hard bar" the more appropriate world would be "build up viscosity".


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## topofmurrayhill

ngian said:


> *Sodium Acetate:* gives only a hard bar (topofmurrayhill maybe can tell us if the soap with sodium acetate cuts down the bubbles, and it is because of the physical hardness of the bar that needs more abrasion to produce the same amount of lather).



Both sodium lactate and sodium acetate appear to increase lather.

http://www.soapmakingforum.com/showpost.php?p=587205&postcount=31


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## Susie

KristaY said:


> Good to know! I had a feeling that might be the thinking behind it. Other than not getting a thicker LS, did you notice a difference in the soap itself? Different lather, different viscosity, different ratio of water needed for dilution, etc?



It diluted differently, less water, if I recall correctly.  I stopped using dual lye just because it was more work for no appreciable benefit before I started keeping really detailed notes.


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## Sapo

Has anyone done any testing with CA yet? I'm wondering how much of it you peeps think one could/should be adding to a standard LS formula? And if it has any adverse effects on clarity and such...


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## Sapo

DeeAnna said:


> If you use citric acid in the sense of its being a chelator and not a neutralizer, then add the extra lye needed for the citric acid to react with --
> 10 g citric acid neutralizes 6.24 g NaOH.
> 10 g citric acid neutralizes 8.42 g KOH.



Is this for 90% KOH? Also, when do I add the CA? Would dissolving it straight in the KOH/water solution (pre-oil merge) be a problem?


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## DeeAnna

Good question! This relationship isn't based on 90% KOH, because I have no idea what purity a person is using -- it can range from 85% to 95%. If you want to do the correction, here's how:

KOH weight adjusted for actual purity = (KOH weight based on 100% purity) * 100 / (Actual KOH purity)

Here's an example of how to use this formula:

Actual KOH purity = 92%
KOH weight based on 100% purity = 52 grams

KOH weight adjusted for actual purity = 52 * 100 / 92 = 55.4 grams


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## Sapo

9.35g KOH (90% purity) per 10g CA it is. Thanks!

Any ideas how much CA to use and when to add it?


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## DeeAnna

See the link under my post for an article about using citrate and citric acid in soap. The info in the article is based largely on what people have shared here on SMF.


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## Sapo

DeeAnna said:


> See the link under my post for an article about using citrate and citric acid in soap. The info in the article is based largely on what people have shared here on SMF.



It says:



> How much citric acid should I use? Typical dosage is 10 g to 30 g citric acid powder for every 1,000 g oils (1% to 3% ppo). Use more for hard water, less for soft.



While for example 3% of 1000g is indeed 30g, 3% ppo (Per Pound of Oil?) is 13.6 grams.

Which is it ?

Very good info in those articles, just a bit confused on that little tidbit.


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## TeresaT

Sapo said:


> It says:
> 
> 
> 
> While for example 3% of 1000g is indeed 30g, 3% ppo (Per Pound of Oil?) is 13.6 grams.
> 
> *Which is it ?
> *
> Very good info in those articles, just a bit confused on that little tidbit.



Both actually.  

If you are weighing your oils in grams, then a 1000 gram batch of oils will need 30 grams (1.07 oz).  Which is 3% weight of oils.

If you are weighting your oils in pounds, then a 32 oz batch of oils will need .96 oz  (26.88 grams).  Which is 3% weight of oils.  


*Since one ounce equals roughly 28 grams, the 1000 gram batch of oils is slightly more than two pounds of oils, which accounts for the slightly higher amount of CA. * 

So, the moral of the story is stick to a unit of measurement; don't mix grams and ounces.  Even though I am an American and the imperial system for "real life" situations, I only soap in grams.    I also don't take the "ppo" literally.  Personally, I view it as "per weight oils" which encompasses metric and imperial units.  It's the number before the abbreviation that you need to concentrate on.  Also, make sure it is supposed to be in relation to the weight of the oils (only) and not the entire batch (which includes your lye solution and all of your additives).


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## Sapo

Well this is embarassing. No idea what the heck I was thinking, lol. Now that I see it, my question  basically: "What is heavier, a pound of feathers or a pound of bricks?"...

Thanks for the reply, and sorry about the confusion. For some reason I was expecting a linear relation between 30g of used CA and completely unrelated measuring units to happen.

:mrgreen:


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## TeresaT

Sapo said:


> Well this is embarassing. No idea what the heck I was thinking, lol. Now that I see it, my question  basically: "What is heavier, a pound of feathers or a pound of bricks?"...
> 
> Thanks for the reply, and sorry about the confusion. For some reason I was expecting a linear relation between 30g of used CA and completely unrelated measuring units to happen.
> 
> :mrgreen:



No worries!  That got me stuck for the longest while, which is why I strictly soap in grams.  Sometimes I'd figure something to be 1.0587 oz and for some reason, my scale will not go to 1.06 oz.  I'll go from 1.05 to 1.07, but never hit 1.06.  I found this extremely frustrating, so I switched to grams and ignored the decimal places.  My scale easily goes to whole number grams and doesn't skip anything.  The thing I have trouble with is when instructions for FOs state .5 oz or 1 oz ppo. In addition, many FOs are sold in volume, not weight, so that's a factor, too.   I prefer it in percentages because it is much easier for me to convert.  But I am the queen of bad math.  If I can figure it out, anyone can!!


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## DeeAnna

"... I also don't take the "ppo" literally. Personally, I view it as "per weight oils" which encompasses metric and imperial units...."

Exactly! Good explanation, T!!! For someone who says she "sux at math" you have a good intuitive understanding of it.


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## DeeAnna

Maybe instead of "ppo" we should say "bwoo" or "bwo" meaning "by weight of oils". I always work only in grams like Teresa, so I have to translate the meaning of ppo like she does. I'm afraid tradition might get in the way of this change, but it's worth a thought....


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## The Efficacious Gentleman

Or "pow" - Percent of Oil Weight.


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## ngian




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## DeeAnna

Hmmm. "POW" has a certain ring to it, don't you think? :mrgreen:


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## TeresaT

I vote for POW!!  Instead of 3% ppo it would be 3 pow.  Totally works for me.


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## The Efficacious Gentleman

How much oatmeal POW did you use?


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## Sapo

Made 3 batches simultaneously, one 3% SF, one 0% SF and one 3% SF with 3% POW CA (as a chelating agent).

The CA batch had a noticably delayed time to paste, compared to the other two. I'm thinking the CA hogs the hydroxide for a while, especially with the subpar mixing I was able to achieve*, leaving the oils sad and lonely for a while - resulting in longer time needed.

*Paste prep inside quart jars, inside 23QT pot. The only way I could think of, to do 3 different batches at the same time. Mixing is predictably harder.


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## topofmurrayhill

Sapo said:


> Made 3 batches simultaneously, one 3% SF, one 0% SF and one 3% SF with 3% POW CA (as a chelating agent).
> 
> The CA batch had a noticably delayed time to paste, compared to the other two. I'm thinking the CA hogs the hydroxide for a while, especially with the subpar mixing I was able to achieve*, leaving the oils sad and lonely for a while - resulting in longer time needed.
> 
> *Paste prep inside quart jars, inside 23QT pot. The only way I could think of, to do 3 different batches at the same time. Mixing is predictably harder.



CA hogs the hydroxide forever, more or less. It reacts with KOH to make potassium citrate, leaving less to react with the oils and thus increasing the SF. Maybe that would slow down the TTP (time-to- paste) also.


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## Sapo

I suppose it would've been prudent to mention in my post above, that I added the appropriate amount of extra KOH (adjusted for actual purity - 5.6g KOH for the 6g CA used), so that SF isn't increased. Theoretically anyway.


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## hlecter

Really interesting posts! I am wondering if sodium citrate can build up some viscosity to a full water (3:1) or on 1 part glycerin LS amount...


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## Sapo

The results in the glycerin LS tests were quite desirable, weren't they...

I'd do the tests, if only I could find some SC to buy.


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## Sapo

A thought sprung up in my head. The theory of adding a chelating agent like SC for boosting soap efficiency is definetly there.

BUT...

Is the reaction between the hard water (Ca/Mg?) and the citrate even fast enough to be noticable while swiftly washing your hands/body?

For example if I put a bunch of citric acid in a bowl with my hard water, I wouldn't expect instant precipitation of calcium citrate, I'd expect it to take a while.

Doesn't seem all that practically useful now that I think about it. Perhaps a wee bit more if using soap as a laundry detergent where the reaction between the chelator and hard water has time to happen.

Thoughts?


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## DeeAnna

In informal tests, it took just a few seconds for soap to react with hard water to form milky soap scum. It took longer for EDTA to reverse that soap scum and turn the water clear again. See: http://www.soapmakingforum.com/showthread.php?t=52456 

Reversing scum formation is not necessarily the same as preventing scum from forming, however. I can tell when I use soap without EDTA in the shower vs soap that includes it, especially when our home water softener runs out of salt so the water isn't especially soft. I don't think it's realistic to expect a chelator in soap to  totally prevent scum -- it would take an unrealistically high dose to get that kind of result -- but it definitely helps.

I will also say you're going to see more obvious results from a chelator when you are showering or washing your hands -- situations where there is only a small amount of water and hard water minerals for the chelator to deal with. It would take a LOT more chelator to deal with the hard water minerals in a washing machine or kitchen sink or bath tub full of water. You're better off to add the correct amount of washing soda or other water softening agent (and/or use a whole house water softener) to control soap scum in these situations.


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## LoveSonam

I am also going to use citric acid as a chelator with NaOH. But at what point do I add it? After I have added NaOH to the water and it has all dissolved? Or after a certain temperature? Or before/with the lye? Or did I just confuse this dramatically?


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## SeaSuds

Hello @LoveSonam.  This post is 4 years old but seeing as how I have an answer that can help which doesn't happen often I'm just going to go ahead!  DeeAnna has written this very useful information: Citric acid, Citrus juice | Soapy Stuff and if you are not confident with the maths then you can just use Soapmakers Friend as your soap calculator and it does it for you.  Add your citric acid to your water and dissolve before adding the lye


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## LoveSonam

SeaSuds said:


> Hello @LoveSonam.  This post is 4 years old but seeing as how I have an answer that can help which doesn't happen often I'm just going to go ahead!  DeeAnna has written this very useful information: Citric acid, Citrus juice | Soapy Stuff and if you are not confident with the maths then you can just use Soapmakers Friend as your soap calculator and it does it for you.  Add your citric acid to your water and dissolve before adding the lye


Perfect! Thank you so much!!


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## Becky1024

LoveSonam said:


> I am also going to use citric acid as a chelator with NaOH. But at what point do I add it? After I have added NaOH to the water and it has all dissolved? Or after a certain temperature? Or before/with the lye? Or did I just confuse this dramatically?


I measure out my distilled water then add the citric acid. Stir until all the citric acid is dissolved. Then start adding the lye.


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