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.
Help me understand the use of Sodium Lactate
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ngian
Well-Known Member
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
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.
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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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.
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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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
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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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.
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.
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
Well-Known Member
See, it's always the man's fault!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.
At least you know and accept, it Lee
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.
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
ngian
Well-Known Member
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
Well-Known Member
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.
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.
ngian
Well-Known Member
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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