# Help me understand the use of Sodium Lactate



## shugohmk

Hello. I think I've done enough research to find out about using SL to CP methods. One article stated using 1tsp per lb of oil. While another talked about percentage and discounting.

Now,

Here is my question or questions.

Let's say I want to make a 2 lb soap (32oz) with 3% SL.

Example (not real recipes)
6oz water
13oz lye
32oz total oils

With percentage: Do I use 2% of 32 oz from the total oils? Or do I use 2% of the 6 oz water?
With Discount: Do I use 6oz water - 2% SL?
With tsp per lb of oil: obviously 2tsp total, I'm just confused for this part actually. Because I have no idea if you have to discount each time you use SL.

Thank you!!!


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## FlybyStardancer

With soaps, additives are normally measured as a percentage of the oil weight (as that is constant, while the amounts of lye and water vary, depending on the individual's superfat level and the concentration used). I've never bothered to subtract from my water weight, but I also don't normally use full water.


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## not_ally

Hi Shug, 

I may not be the best person to give advice on this b/c I'm not experienced enough, but here's my experience/the feedback I have recieved.  I made my first few batches w/o SL and then started adding it b/c it seemed to make it easier to unmold, plus it is supposed to be a humectant, so I thought why not?  

I have a problem w/hard water, though, so when I posted my recipe a number of experienced posters suggested omitting the SL, which I now do unless I think I will have a problem unmolding for some reason.  The reason for those suggestions was basically that most formulas will permit you to unmold fairly easily, even if you have to wait a bit longer, and that less is more in many cases with soap, especially when you are starting out like we are.   

W/r/t how much to add, I just used the MMS calculator, that includes an SL entry, and would to try estimate what percentage was good for unmolding that particular recipe (I think it goes from 1-3% ppo).  I just added whatever the amount was to the cooled lye water, did not discount.


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## shugohmk

Very informative. I didn't think there was a calculator with SL. Do you mind providing the link for that? Thanks!


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## not_ally

Sure, here it is is (the SL slot is three or four above where the oil entries start):

https://www.thesage.com/calcs/LyeCalc.html


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## shunt2011

I use SL in my soaps to make it easier to unmold from my silicone molds.  I use it between 2-3% and works great.


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## Saponista

Do you notice any difference in the overall feel of the soap when you add it shunt?


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## Dahila

I add it at 2% PPO and it does make a difference, easier to unmold, better, much better lather) I think the bubbles last longer too


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## shunt2011

I too think it add a bit to the lather.  I mainly like it for the unmolding firmness it adds.


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## Chefmom

I use it in all of my recipes at 2 1/2% of my oil weight.  I primarily hot process and it has a huge impact on the final batter after cooking at molding time.  It also gives me a stronger bubbly bar in my final product.  Hardness overall?  I'm not entirely sure because I mostly shoot for hard bars in the first place and without testing it in a known soft bar recipe I can't say that with certainty.


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## shugohmk

When is the right time to discount water for the SL?

How would you discount if you're making a milk soap at 50/50?


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## shunt2011

I don't discount my liquid for SL.  If I did I would just subtract that amount from my milk in my 50/50 mix.


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## LBussy

Chefmom said:


> I primarily hot process and it has a huge impact on the final batter after cooking at molding time.


Can you elaborate?  I've read people using it but not tried it myself - nor am I really sure WTH it's supposed to do.


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## DeeAnna

In hot process or rebatched soap, adding sodium lactate makes the hot soap more fluid. In my experience, this type of soap without SL might have a texture like mashed potatoes made without milk -- it might be really well mixed, but it still has a kind of chunky texture. With SL, the same soap might be more like mashed potatoes with a generous dollop of cream -- well mixed and almost pudding-y. The molded soap with SL will often look more like CP soap, rather than the rough, rustic texture that HP or rebatch soap usually has.

Since handcrafted soap normally contains 10% glycerin by weight, give or take a bit, I'd say adding SL as a humectant isn't probably adding much to the party.

Oh, and some use SL when diluting liquid soap -- added at 3% by weight of the dilution water, it helps soften the soap paste to make it dilute faster.


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## kisha

So would you add the SL after of before cooking it?


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## SplendorSoaps

Since we're on the SL topic...  I've been hesitant to use it because I'm not sure how customers looking for all natural ingredients might react.  I like to keep my ingredient lists pretty short, sweet, and easy to pronounce!  LOL  

I know SL is derived from vegetable fermentation, but I think the SL we buy for soap making is processed,  or maybe nature-identical.  Just curious, for those who use SL, how do you respond if you're asked if SL is a "natural" product (I know, "natural" is such a loaded term and means something different to everyone)?


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## LBussy

Thanks DeeAnna, as alway I appreciate the info.


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## DeeAnna

"...So would you add the SL after of before cooking it? ..."

Either would work for HP, in my opinion. Whichever is easiest for you.
You'd add SL to rebatched soap when the soap is soft enough you can stir the SL into the soap.
You'd add SL to the dilution water for liquid soap.


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## The Efficacious Gentleman

I always added my powdered SL to the water before I added the lye. If I used liquid SL, I think I'd add it in to the oils before the lye water. 

It has an odd effect in hp - the soap is basically a gel, but also behaves like liquid. So it's very easy to scoop out of the pot and in doing so it behaves like a liquid, but then it is like a gel when you pour it in to the mould.

When I first made it, I really had no idea if it was right or not!


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## DeeAnna

I know what you mean, Gent. The texture is kinda neat, but kinda weird all at the same time. Remember my contribution to the recent thread about boiling and salting-out scrap soap? I added SL to that soap and it got that odd liquidy but gelatinous texture you describe. Kind of like a gravy made with corn starch (aka cornflour) as it cools down.

The Geeky Soaper's word for the day is "thixotropic" (thicks-uh-tropic). More: http://en.wikipedia.org/wiki/Thixotropy  :mrgreen:


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## Chefmom

LBussy said:


> Can you elaborate?  I've read people using it but not tried it myself - nor am I really sure WTH it's supposed to do.



Like others have now mentioned....it's the difference of dry poorly made mashed potatoes and freshly cooked pudding.  Lumpy and thick vs. smooth and creamy.

Before I used it regularly my finished HP mixture was hard to put in the molds without some air pockets against the sides and bottom.  I did a lot of pushing down and banging, but with the sodium lactate addition it glides right into the molds and is easier to scoop all of it out of the crock pot with minimal loss to clinging to the sides etc.

http://www.soapmakingforum.com//www.pinterest.com/pin/create/extension/


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## LBussy

Does it seem ironic to anyone else that a lot of people get into making soap so they can use a product with less "chemicals", and we end up adding many of them back in?

Don't get me wrong, I'm not a chemophobe ... I just find it ... well, ironic.


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## The Efficacious Gentleman

For me the difference is a man-made version of a natural chemical (lye, for example) verses chemicals that don't actually exist outside of that which man makes.  Let's be honest, there is no such thing as a natural pommace OO as it is solvent extracted.  From that basis things like sodium lactate, sodium citrate and so on have a different place than polymonomanmadeparabenoxide


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## LBussy

The Efficacious Gentleman said:


> For me the difference is a man-made version of a natural chemical (lye, for example) verses chemicals that don't actually exist outside of that which man makes.  Let's be honest, there is no such thing as a natural pommace OO as it is solvent extracted.  From that basis things like sodium lactate, sodium citrate and so on have a different place than polymonomanmadeparabenoxide


I think using these chemicals forces us to learn about them. Since we are adding them, and we do so armed with an understanding of what they are and do, we feel better about it.  

So now that we are talking about SL ... anyone elver used Potassium Lactate?  They both seem to be metallic salts resulting from the neutralization of lactic acid.  One might surmise that it would be possible to make at home with lactic acid and lye ... or similar to Sodium Citrate, by adding the acid directly to the mix and accounting for the lye consumption.


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## Chefmom

The Efficacious Gentleman said:


> For me the difference is a man-made version of a natural chemical (lye, for example) verses chemicals that don't actually exist outside of that which man makes.  Let's be honest, there is no such thing as a natural pommace OO as it is solvent extracted.  From that basis things like sodium lactate, sodium citrate and so on have a different place than _*polymonomanmadeparabenoxide*_



Okay....I have to take a moment to say that I first did my best to pronounce this...and then laughed out loud...for a very long time.  Still giggling a bit.....


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## DeeAnna

"... One might surmise that it would be possible to make at home with lactic acid and lye..."

Yes, you surmise most correctly! Only problem -- where to find the lactic acid. Citric acid is pretty easy to find, even in grocery and hardware stores, so I'm willing to mess with turning it into sodium citrate. On the other hand, I've never seen lactic acid in a grocery store aisle. If I have to order lactic acid from Lotioncrafter or other chemical supplier, I figure I might as well buy the sodium lactate, unless I have some other use for lactic acid besides turning it into sodium lactate. Maybe I'm missing something???


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## FlybyStardancer

It's not in a pure form, but additives like buttermilk would have a decent amount of lactic acid.  (I happened to catch a factoid somewhere that buttermilk has one of the highest lactic acid contents.)


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## LBussy

DeeAnna said:


> Yes, you surmise most correctly! Only problem -- where to find the lactic acid.


Seems like I have a lot of crossover chemicals/gear in my hobbies.  LA is regularly used by Home Brewers to adjust the pH of the mash.  I have tons.


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## IrishLass

The Efficacious Gentleman said:


> polymonomanmadeparabenoxide


 

Being that it's still April Fools day, I am almost tempted to start a thread to inquire where one might be able to purchase such a thing, or if anyone has used it in their soap. :razz:


IrishLass


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## DeeAnna

We have a homebrew store in the local area -- I'll have to investigate.


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## ngian

DeeAnna said:


> "... One might surmise that it would be possible to make at home with lactic acid and lye..."
> 
> Yes, you surmise most correctly! Only problem -- where to find the lactic acid. Citric acid is pretty easy to find, even in grocery and hardware stores, so I'm willing to mess with turning it into sodium citrate. On the other hand, I've never seen lactic acid in a grocery store aisle. If I have to order lactic acid from Lotioncrafter or other chemical supplier, I figure I might as well buy the sodium lactate, unless I have some other use for lactic acid besides turning it into sodium lactate. Maybe I'm missing something???



And what is the amount of Lye that is needed to make sodium lactate out of lactic acid? I can find sodium lactate solution 60% and lactic acid but the acid must be cheaper (will learn tomorrow) .

I'm thinking of using SL instead of salt, along with sodium citrate, 1-2% sugar and part of the liquid with beer in a castile soap or in a low amount of CO/PKO recipe. Are all the above additives will create a full lather product,  or a soap failure because I am using too many additives?


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## LBussy

ngian said:


> And what is the amount of Lye that is needed to make sodium lactate out of lactic acid? I can find sodium lactate solution 60% and lactic acid but the acid must be cheaper (will learn tomorrow) .
> 
> I'm thinking of using SL instead of salt, along with sodium citrate, 1-2% sugar and part of the liquid with beer in a castile soap or in a low amount of CO/PKO recipe. Are all the above additives will create a full lather product,  or a soap failure because I am using too many additives?


If my math is right (and DeeAnna will tell me if it's not):

NaOH + C3H6O3 -> NaC3H5O3 + H2O  or
KOH + C3H6O3 -> KC3H5O3 + H2O				

So:
1g of Lactic acid neutralizes 0.44g of NaOH and creates 1.24g Sodium Lactate
1g of Lactic acid neutralizes 0.62g of KOH and creates 1.42g Potassium Lactate


Which means if you want:
1g of Sodium Lactate you need to add 0.81g of Lactic Acid and 0.35g of NaOH
1g of Potassium Lactate you need to add 0.70g of Lactic Acid and 0.44g KOH

I think. 

ETA:  DeeAnna if you read this my math balances for that one but the closest I can get for Sodium Citrate is:

9(NaOH) + 3(C6H8O7) -> 3(Na3C6H5O7) + 7(H2O) + O2

... which misses balancing by .43% for some reason I can't figure out.  Rounding errors maybe?


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## LBussy

LBussy said:


> So:
> 1g of Lactic acid neutralizes 0.44g of NaOH and creates 1.24g Sodium Lactate
> 1g of Lactic acid neutralizes 0.62g of KOH and creates 1.42g Potassium Lactate
> 
> Which means if you want:
> 1g of Sodium Lactate you need to add 0.81g of Lactic Acid and 0.35g of NaOH
> 1g of Potassium Lactate you need to add 0.70g of Lactic Acid and 0.44g KOH


I should probably also add that anhydrous lactic acid is likely not going to be seen outside of a chem lab.  You can buy 88% pretty easily.  So with 88% Lactic Acid we are more around:
1g of 88% Lactic acid neutralizes 0.39g of NaOH and creates 1.09g Sodium Lactate
1g of 88% Lactic acid neutralizes 0.55g of KOH and creates 1.25g Potassium Lactate

Which means if you want:
1g of Sodium Lactate you need to add 0.92g of 88% Lactic Acid and 0.35g of NaOH
1g of Potassium Lactate you need to add 0.80g of 88% Lactic Acid and 0.44g of KOH

BUT ... remember KOH is often 90% so ... to get 1g of Potassium Lactate you need to add 0.80g of 88% Lactic Acid and 0.49g of 90% KOH

Yeah, that's enough math for tonight.


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## The Efficacious Gentleman

ngian said:


> And what is the amount of Lye that is needed to make sodium lactate out of lactic acid? I can find sodium lactate solution 60% and lactic acid but the acid must be cheaper (will learn tomorrow) .
> 
> I'm thinking of using SL instead of salt, along with sodium citrate, 1-2% sugar and part of the liquid with beer in a castile soap or in a low amount of CO/PKO recipe. Are all the above additives will create a full lather product,  or a soap failure because I am using too many additives?




As the acid question is covered (very well, if I might add) pending confirmation, I will say that the additives you use certainly can increase lather, but I'm not sure if any can create lather. There is a difference, as Castile is notorious for lathering badly and the additives can improve that, but only within the confines of what they have available to them. So it should indeed improve the lather, but whether or not you get to a type of lather that you are looking for...........possibly. But it will certainly need a good long cure (maybe 6 months) cure regardless.


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## DeeAnna

Finally got to looking at your numbers, Lee. They look fine -- kudos to you! 

You asked:
"...DeeAnna if you read this my math balances for that one but the closest I can get for Sodium Citrate is:
9(NaOH) + 3(C6H8O7) -> 3(Na3C6H5O7) + 7(H2O) + O2
... which misses balancing by .43% for some reason I can't figure out. Rounding errors maybe?..."

Isn't the stoichiometry more like this:

3(NaOH) + C6H8O7 -> 
3(Na+) + 3(OH-) + (C6H5O7---) + 3(H+) -> 
Na3C6H5O7 + 3(H2O)

3 moles NaOH + 1 mole citric acid -> 1 mole trisodium citrate + 3 moles water


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## LBussy

DeeAnna said:


> Isn't the stoichiometry more like this:
> 
> 3(NaOH) + C6H8O7 ->
> 3(Na+) + 3(OH-) + (C6H5O7---) + 3(H+) ->
> Na3C6H5O7 + 3(H2O)
> 
> 3 moles NaOH + 1 mole citric acid -> 1 mole trisodium citrate + 3 moles water


It is!  Taking the intermediate step of the dissociated ions made it a little less cluttered for me.  Not quite sure how I missed it but it definitely works now.


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## DeeAnna

Good! Glad that helped, Lee. I thought including that middle equation might clarify things a bit for you. 

Another thing that is helpful to me (but I know might be absolute greek to many) is to rewrite the basic formula for citric acid ... C6H8O7 ... in a way that shows more about its structure. Rewritten, the formula looks like this ... C3H4OH-(COOH)3 ... The three "COOH" sections are the "carboxyl" groups that gives citric acid its acidic nature. The "H's" in the chemical equations in my post above are the H's that come off the acidic COOH parts of the molecule. Since there are three COOH's, there are three H's to play with.

What's cool about citric acid is there are THREE of those little carboxyl critters and thus three H's, which is why you don't need much citric acid to do a job compared with the other "weak" acids sometimes used in soaping, such as vinegar (acetic acid). 

Acetic acid's basic formula is C2H4O2. Rewritten to highlight its acidic nature, the formula for acetic acid looks like this ... CH3-COOH ... See how there's only one carboxyl group? You can get only one H from the acidic COOH to play with.


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## LBussy

Okay that makes sense ... acetic acid (methanecarboxylic acid) is a carboxyl and an alkane (I guess that's where the "methane" part comes from?) where lactic acid has the three carboxyl groups and is sort of a triple "strength" acid compared to acetic.  So that's why you need ~20% more lye to neutralize a given mass of citric acid versus lactic.

Now the big question:  Since both R-lactate and R-citrate have one molecule of their associated metal and R-lactate has 56% of the molar mass of R-citrate, that implies by mass, using R-citrate would require 43% more to achieve the same thing? (or did I get that backwards?)

And then examining the chelating effect of each:  Sodium, Potassium, Calcium and Magnesium are the alkali metals at play here.  Potassium and Calcium are in the same period where Sodium and Magnesium are in the same period.  Generally, elements within a period go from most to least reactive; calcium and magnesium being alkali-earth metals, each have one more proton than it's partner in the period.  How then does the salt preferentially associate with the less reactive metal?  And then also considering those periods, will a potassium salt more freely chelate calcium and the sodium more freely chelate the magnesium?

And does THAT mean we might consider the makeup of the tap water when choosing between potassium and sodium salts?

And at what point should we have removed this from the "Beginner" forum?


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## DeeAnna

Lee -- Your questions are stretching my little brain cells pretty good, so, yeah, this has definitely moved out of the beginner forum.

First, here's a definition of chelation:

"...Chelation (a word derived from the Greek word “chela”—a claw) is based on the simple fact that two or more attractive forces acting simultaneously on a metal atom are stronger than only one. A chelating agent is a molecule which contains at least two groups of polarity opposite to that of the atom it is wanted to remove, in such a sterical position as to fit the size of that atom, thus exerting a double or multiple pull on it...." Source: A Textbook on EDTA Chelation Therapy: Second Edition, by Elmer M. Cranton, 2001.

One point to take from this definition is that a chelator is a molecule (or ion) that can bond with a metallic atom in two or more places. Each individual fastening point might be relatively weak, but since the chelator is can form two or more bonds, it can create a firm overall connection with the metal.

Another point is the geometry of the connection has to be favorable for the bond to form. The chelator due to its geometry can wrap itself around the metallic atom -- nestling the metal within its bosom, so to speak. One mental picture I get of this is how a baseball nestles into a catcher's glove. The shape of the pocket in the glove is just right to hold the ball securely without a lot of pressure or effort.

***

"...How then does the salt preferentially associate with the less reactive metal? And then also considering those periods, will a potassium salt more freely chelate calcium and the sodium more freely chelate the magnesium?..."

I am not certain, but I don't think in this case that it's the citrate salts are doing the chelating -- it's the citrate ions. The "hard water" metals are ions with two positive charges (typically Ca++ and Mg++). A citrate ion has three "claws", each with a negative charge. The multiple connections between the citrate ion and the Mg or Ca ion are key to creating a relatively strong bond. 

Now think about how citrate forms a bond with sodium or potassium. The citrate can make only one point of connection with a K or Na ion, because these ions have only one positive charge -- K+ or Na+. This single point of connection means citrate can't act as a chelator for these ions. Because K and Na have a strong ionic nature, the bond is more subject to being broken -- in effect, K and Na don't form strong covalent bonds; they can be quite happy as ions rather than stay bonded to other atoms.

There's my non-expert explanation of the difference.

***

Your general thoughts about the periodic table have merit, but the reactivity of any given set of atoms is more complicated than how you describe it. 

The ability of atoms to donate and/or accept electrons, the geometry of the atoms/ions within a given chemical mix, the size of the electron cloud around each atom, the nature of the bonds between atoms, etc. -- all these factors enter into the chemical shenanigans going on at any given moment.

 Speaking very generally, atoms on the far left side of the table are electron donors, and those on the far right are electron acceptors (not counting the extreme right column that contains the noble gases). Some atoms more-or-less in the middle (carbon for example) can walk either side of the street, depending on the circumstances. 

As you go down any column or from left to right in any row, the atoms have increasingly larger electron clouds. A larger electron cloud means the outer electrons of an atom are further away from the nucleus and are more likely to form weak bonds with other molecules and ions.


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## DeeAnna

Since you asked your question, Lee, I got curious about EDTA's role as a chelator in soap, since EDTA is also used in soap to reduce the chance of rancidity (aka DOS) and reduce scum formation. The product that we use in soap is tetrasodium EDTA -- this is basically the four-sodium salt of the acid, just as trisodium citrate is the three-sodium salt of citric acid.

"...[EDTA's] usefulness arises because of its role as a hexadentate ("six-toothed") ligand and chelating agent, i.e., its ability to "sequester" metal ions such as Ca2+ and Fe3+. After being bound by EDTA, metal ions remain in solution but exhibit diminished reactivity..." Source: Wikipedia, http://en.wikipedia.org/wiki/Ethylenediaminetetraacetic_acid

Wowser ... and I thought citrate's three claws were interesting ... but EDTA has six! The basic formula of EDTA is C10H16N2O8, but if you rearrange the formula to show the acidic nature of EDTA, the formula looks like this -- C6N2H12-(COOH)4. 

When EDTA is in solution, it becomes a chelator in two ways. First, the four acidic carboxyl (COOH) groups each lose a hydrogen ion (H+). That creates four negatively-charged claws. This is exactly the same as what citric acid does to create its three claws.

The two nitrogen atoms (N) buried in EDTA's structure create the remaining two claws. These claws are a little different. The nitrogen atoms -- called "amines" -- each have unattached electrons that are looking for something to do. Like bored teens running around on Saturday night, they join forces with the four acidic claws and gang up on an unsuspecting metal ion.

The poor calcium or magnesium or iron ion (Ca++ or Mg++ or Fe+++, etc.) never has a chance. The EDTA molecule envelops the metal ion on all sides and locks it in place with its claws. 

Arrrrrrrrr!!!! Chemical piracy at its best! :twisted:


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## topofmurrayhill

Tetrasodium EDTA in your water and BHT added to the oils locks down the stability of your soap. I have bars that have a 6 year cure on them and are unchanged.


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## ngian

LBussy said:


> I should probably also add that anhydrous lactic acid is likely not going to be seen outside of a chem lab.  You can buy 88% pretty easily.  So with 88% Lactic Acid we are more around:
> 1g of 88% Lactic acid neutralizes 0.39g of NaOH and creates 1.09g Sodium Lactate
> 1g of 88% Lactic acid neutralizes 0.55g of KOH and creates 1.25g Potassium Lactate
> 
> Which means if you want:
> 1g of Sodium Lactate you need to add 0.92g of 88% Lactic Acid and 0.35g of NaOH
> 1g of Potassium Lactate you need to add 0.80g of 88% Lactic Acid and 0.44g of KOH
> 
> BUT ... remember KOH is often 90% so ... to get 1g of Potassium Lactate you need to add 0.80g of 88% Lactic Acid and 0.49g of 90% KOH
> 
> Yeah, that's enough math for tonight.



Thank you LBussy for ALL the above information! 

1lt of powder lactic acid costs 5,5€ (I asked also for the purity to do the math correctly and he told me it is around 80-85, he can check the msds when I'll buy it) while sodium lactate 60% liquid in another shop costs 2,9€ /50ml. 

I have to do a lot of math as I will also have 85% KOH

I have to also make an excel file to do all the above math, like the one DeeAnna had made. 

Nikos


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## not_ally

Ok, you guys, some of you know I am the woman with the hardest/soap scummiest water on earth.  I have tried EDTA (at .5%, it has helped a lot), and have bars w/citric acid and sodium citrate that are curing.  DeeAnna, almost all the science stuff went way over my head, but it seemed like one take away is that EDTA has more "clawy"chelating properties than anything else.  So if it were you, would you try to add (eg) both EDTA and Sodium Citrate or just up the amounts of EDTA solution (I use it in a 39% solution so it is dissolved, might just discount the regular water amount if it gets to the point that it matters.)

ETA: Eg, if using chelators, do they have individual qualities that might merit using a combo rather than just one?  Feel free to ignore if this is one of those questions that takes too much work to answer.


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## DeeAnna

I don't really know the answer to that, NotAlly, but here's what I've been doing with my soaps, and maybe it will help you decide --

I am adding EDTA to my soaps to reduce soap scum and slow down rancidity (aka DOS). Except for a couple of experimental batches (see next part below), I've been using EDTA at about 0.5% ppo based on the EDTA in its powder form. That translates to about 1.3% ppo based on a 39% EDTA solution (39 grams EDTA powder plus enough water to make a total of 100 grams of solution).

Most of my recipes are high in lard, and I use store-bought lard that is preserved by the producer with BHT (an antioxidant) and citric acid. That means I'm getting a blend of chelators in my soaps, one way or the other. I also add ROE (rosemary oleoresin) to my my liquid oils and coconut oil as another antioxidant. ROE and BHT don't help with soap scum, but they do protect against rancidity.

***

I have been experimenting with adding a higher dose of EDTA to my last 2 batches of soap. 

In my reading, I learned that EDTA can be used as high as 3% (on a powder basis), so I tried that in my latest batch of laundry soap. The soap recipe was 30% store bought lard and 70% coconut with added ROE, NaOH, and plain distilled water. I blended the EDTA (as a 39% solution) to my fats right before adding the lye solution to the fats, and the soaping process went along just fine with no surprises. 

I next used 2% EDTA (on a powder basis) in a batch of gardener's soap made with 75% lard, 20% coconut, 5% castor, so again I'm getting BHT and citrate in the lard and ROE in the coconut. I added the EDTA (as a 39% solution) and 3% ppo table sugar to the distilled water before adding the lye. That step went fine, but when I added the lye, the mixture quickly turned into a white pudding-y mess. From my reading, I had understood that EDTA does not react with NaOH, but obviously between the EDTA, the sugar, and the lye, something reacted unhappily with something. I discarded that mess and made a sugar-water-lye solution without the EDTA -- no problems. I blended the EDTA solution into the oils like I did with the laundry soap, and again all seemed to go fine.

I need to try just EDTA solution, water, and lye to see how that behaves without the sugar to complicate things.

***

The chelators mentioned not only reduce soap scum, they also protect against rancidity (DOS). If you want to add a second ingredient to further protect against DOS, I'd add an antioxidant such as ROE (rosemary oleoresin) or BHT. The antioxidants won't help with the soap scum problem, just so's you know. 

In his experiments on how to slow down the oxidation of soap, Kevin Dunn got effective results with these combinations. 1 ppt means 1 part per thousand parts based on the weight of the fats and based on EDTA in its powder form. So for a recipe with 1000 g of fat, you'd add 1 g of EDTA powder to get a dose of 1 ppt EDTA in the batch.

1 ppt EDTA and 1 ppt BHT
1 ppt citrate and 1 ppt BHT
1 ppt EDTA and 1 ppt ROE

The citrate and ROE combo didn't work well for him, so he didn't recommend that.

***

This is a bit rambly and there's not a lot of hard data to help you with your decisions, but I hope my experiences will give you some ideas.


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## not_ally

DeeAnna, thought I had replied to this yesterday, but I think something was going on with the board yesterday am (couldn't sign on for a while and then a couple of replies got lost).  Anyway, I just wanted to say a heart-felt thank you for your post.  This is a weirdly important topic for me, so your informed input is important.  I sometimes (ok, often) don't get the science behind your posts, but I love that you are always willing to help.

ETA:  My recipe (still tweaking a basic one) is high lard also, and I use Smart and Final Lard, which also (maybe it is the same as yours) contains BHT and CA.  They don't tell you how much, which worried me a bit, but then I decided it was probably a good thing (w/r/t chelation and DOS), not that much, and I just proceed as if they were not there in terms of calculations.  

Re EDTA and sugar, I use them both (the EDTA at .5 %) and sugar in a 50/50 simple syrup added at trace at about 1TB ppo.  I'm not sure how that compares in terms of your amounts, but it has not been a problem for me in those proportions at least so far.  Just wait, though, I am going to make a batch of soap today, I have probably jinxed myself.  Newbie soap hubris


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## DeeAnna

Oh, part of my problem with the white pudding is the amount of EDTA I was trying out -- 3%. That's quite a lot and most likely overkill, given that you say you are seeing benefits from 0.5% EDTA with your very hard water. Glad I could contribute. I agree I sometimes do go overboard with the science-y stuff. In this thread, you can blame Lee and his question about chelators -- he's the reason that I let my inner geek run wild for a bit.


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## not_ally

For some reason that 3% percentage did not filter into my little pea brain, I think I mixed it up with the 39% solution part.  I did not know that the max was anywhere close to 3%, I thought it was much lower.  That makes me happy though, I am going to go higher (than the .5 I am using now) and see if there is a level at which I can get scum free water *and* avoid pudding.   That would be a happy outcome.  

Never apologize for the scienc-y stuff.  I always read it and find it interesting, even if I don't understand it.  And I know if I needed to, I could ask you!

ETA:  I don't want to seem like Malibu Barbie and make you science types feel bad about talking about it.  I am super smart in some ways, but the math/science thing is like a big giant mental block for me.  My dad is/was - pre-retirement- a biochemist (Phd in Molecular Biology) and when he talks about it, it is so beautiful and elegant in a mysterious way that I can never really fully understand.  I really wish I could understand the nitty gritty parts and do enjoy it when you guys go all out, even if I am not able to completely comprehend it.


Quote: "Oh, part of my problem with the white pudding is the amount of EDTA I was trying out -- 3%. That's quite a lot and most likely overkill, given that you say you are seeing benefits from 0.5% EDTA with your very hard water.Glad I could contribute. I agree I sometimes do go overboard with the science-y stuff. In this thread, you can blame Lee and his question about chelators -- he's the reason that I let my inner geek run wild for a bit.


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## LBussy

DeeAnna said:


> In this thread, you can blame Lee and his question about chelators -- he's the reason that I let my inner geek run wild for a bit.


See, it's always the man's fault!


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## not_ally

At least you know and accept, it Lee


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## topofmurrayhill

LBussy said:


> So now that we are talking about SL ... anyone elver used Potassium Lactate?  They both seem to be metallic salts resulting from the neutralization of lactic acid.  One might surmise that it would be possible to make at home with lactic acid and lye ... or similar to Sodium Citrate, by adding the acid directly to the mix and accounting for the lye consumption.



Funny you should ask. I've made exactly one liquid soap. I calculated a relatively generous lye excess and then reacted the remaining caustic with lactic acid to create potassium lactate. I can't tell you much except that it was a very good soap.


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## topofmurrayhill

not_ally said:


> Ok, you guys, some of you know I am the woman with the hardest/soap scummiest water on earth.  I have tried EDTA (at .5%, it has helped a lot), and have bars w/citric acid and sodium citrate that are curing.  DeeAnna, almost all the science stuff went way over my head, but it seemed like one take away is that EDTA has more "clawy"chelating properties than anything else.  So if it were you, would you try to add (eg) both EDTA and Sodium Citrate or just up the amounts of EDTA solution (I use it in a 39% solution so it is dissolved, might just discount the regular water amount if it gets to the point that it matters.)
> 
> ETA: Eg, if using chelators, do they have individual qualities that might merit using a combo rather than just one?  Feel free to ignore if this is one of those questions that takes too much work to answer.



Here is the work by Kevin Dunn that DeeAnn referred to. You might find this very interesting. A slightly revised version of this is a chapter in Dunn's Scientific Soapmaking book.

http://cavemanchemistry.com/DreadedOrangeSpot-Dunn.pdf


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## ngian

LBussy said:


> I should probably also add that anhydrous lactic acid is likely not going to be seen outside of a chem lab.  You can buy 88% pretty easily.  So with 88% Lactic Acid we are more around:
> 1g of 88% Lactic acid neutralizes 0.39g of NaOH and creates 1.09g Sodium Lactate
> 1g of 88% Lactic acid neutralizes 0.55g of KOH and creates 1.25g Potassium Lactate
> 
> Which means if you want:
> 1g of Sodium Lactate you need to add 0.92g of 88% Lactic Acid and 0.35g of NaOH
> 1g of Potassium Lactate you need to add 0.80g of 88% Lactic Acid and 0.44g of KOH
> 
> BUT ... remember KOH is often 90% so ... to get 1g of Potassium Lactate you need to add 0.80g of 88% Lactic Acid and 0.49g of 90% KOH
> 
> Yeah, that's enough math for tonight.



Hello Lee

It seems that I need your help once again if you will.

I have NaOH  (>=99% pure) 







and I can buy Lactic Acid that is ~80% 






and I'm thinking of making a liquid 60% Sodium Lactate.

Could you be kind enough to tell me how much distilled water, NaOH and Lactic Acid should I use to create around 100ml of 60% SL?

Is there anyway in the end (maybe zap or ph tapes?) that I can assure all the NaOH will be neutralized? 

Thank you very much in advance.
Nikoshttp://www.soapmakingforum.com//www.pinterest.com/pin/create/extension/


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## LBussy

ngian said:


> I'm thinking of making a liquid 60% Sodium Lactate.
> 
> Could you be kind enough to tell me how much distilled water, NaOH and Lactic Acid should I use to create around 100ml of 60% SL?


If you mean make a 60% Sodium Lactate solution - yes.  The math is nearly the same as I've showed above.  If stoichiometry tells us that .81 parts of Lactic Acid combined with .35 parts of Lye gives us 1 part of Sodium Lactate, you would take the purity divided by the ratio to give you the new ratio:

Lye:  0.99 (99% purity) / 0.35 (original amount) = 0.3535353535 (let's call it 0.35)
Lactic Acid: 0.80 (80% purity) / 0.81 (original amount) = 0.99

Now we know that to get 1 gram of Sodium Lactate, we need 0.99 grams of your 80% Lactic Acid and 0.35 grams of your 99% lye.

Since we used 2.34 grams of our components combined to make 1 gram of sodium lactate, the remainder can be assumed to be 1.34 g of water.  In reality it is made up of water and whatever impurities are in the chems at the same ratio as the original components.  You have 0.18g of impurities from your 80% LA and 0.004g of impurities from your 99% NaOH for a total of 0.184g of impurities dissolved in your remaining water.   So, to keep things honest your "remainder" is water of a minimum 86% purity.  Since the largest amount of impurities comes from the lactic acid, and BY FAR the largest impurity there is water, I believe we're safe calling it 100% water for our purposes.

The solution you have will be a 75% solution of SL.  Now of course you can't just sprinkle lye into Lactic Acid (well you could but I would not recommend it) so the lye needs to be in solution first before we combine things.  

At 20 °C (68 °F) the solubility of NaOH is 1110 g/L.  To make it easy, let's say the max concentration you can/should work with is 100% (1000 g/L).  We now have water in an amount equal to the weight of the lye so it now looks like:

0.99g LA + 0.35g NaOH + 0.35g H2O = 1g SL + (1.34g + 0.35g) H2O

1g SL / 1.69g H2O = 60% SL solution

Ironic how pulling "round numbers" out of the air made it come out to what you wanted, but there it is.  



> Is there anyway in the end (maybe zap or ph tapes?) that I can assure all the NaOH will be neutralized?


If you are off by a percent or two but still use it to make soap, it will simply use part of your intended superfat (or contribute to it).  The amount is so low it's negligible compared to the amount of error there might be in the soap batch.  In theory the pH of the sodium lactate solution will be neutral (7.0) but if it's not, you really have no idea how much of what to add without a titration which is a different test entirely.  I'd just let it go and let it balance out in the soap.

This is a real quick off the cuff answer, so double-check the math and/or wait to see if anyone shoots holes in my logic.


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## ngian

LBussy said:


> This is a real quick off the cuff answer, so double-check the math and/or wait to see if anyone shoots holes in my logic.



Thank you very much Lee for your contribution 

I'm keeping all the above in my evernote for future study and reference for when I'll get the Lactic Acid.



http://www.soapmakingforum.com//www.pinterest.com/pin/create/extension/


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