Sodium citrate from baking soda and citric acid

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SoapSap

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I just bought food grade Sodium Citrate and would like to know if I can use this in my soap as well as you it in food applications?
 

DeeAnna

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Update on my sodium citrate solution: The sodium citrate solution at 33% concentration is water clear with only a faint trace of solids on the bottom of the container. The solids could easily be impurities from my food-grade baking soda and citric acid -- I was using grocery store products, not lab-quality stuff.

A 50% concentration does not work -- not all of the SC will dissolve. I think, however, that I could have made a 40% concentration, per Patrick's info, so that's on my list to try next time.

***

To recap what I did with a revision for the starting amount of water to use:

100 g citric acid
131 g baking soda
300 g distilled water
Plus more distilled water for dilution after the reaction is done

Find a container that a LOT larger than the total volume of your ingredients. (For this recipe, I'd use a 3 quart container.) The container should be glass, stainless steel, plastic, or porcelain-enamel coated. Do not use aluminum. (It's not going to do anything horrible if you do use aluminum, but the citric acid will react with aluminum, just like tomato sauce does, rather in addition to reacting with the baking soda.) Weigh your container and record that weight.

Put the water into the container and dissolve the citric acid in the water. Gradually add spoonfuls of baking soda to the mixture and stir. The mixture will foam exuberantly, so add the baking soda gradually enough that you can control the foaming with stirring.

After the baking soda is all added, the mixture will continue to fizz and foam. You will also find the container will get quite chilly, and that's okay. Stir as necessary to keep the foam from overflowing your container. Once the foaming slows down enough to stay inside your container, you can leave the mixture to fizz away on its own for several more hours. It's done when there is no more fizzing.

You may end up with a mixture of clear liquid and white solids or just a clear solution. Either way is fine. Once the mixture is fully reacted, weigh the container plus its contents and calculate the water in the mixture:
Water weight after the reaction = Total weight - Container weight - Sodium citrate weight

The theoretical sodium citrate weight for this example is 134 grams, so:
Water weight after the reaction = Total weight - Container weight - 134 g

Add enough extra water to make a 33% (or 40%) solution, whichever you prefer. For a 33% concentration, this "Final water weight" should be about 406 g for this particular recipe. For a 40% concentration, the "Final water weight" should be 335 g.

We already have some water in the mixture (see above for "Water weight after the reaction"). Subtract this weight from your desired "Final water weight" to get the water to add to end up with the concentration you want.
Water to add = Final water weight - Water weight after the reaction

Add this extra water to the mixture. The white solids should mostly or entirely disappear. Store this sodium citrate solution in a plastic or glass bottle for use in your soap.

***

Thanks, Galaxy, for sharing your idea and your methods!
 
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Dahila

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I am using CA for some time but I put it into water and dissolve before adding lye. With Sodium citrate is the same? Before lye?
 

commoncenz

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I am using CA for some time but I put it into water and dissolve before adding lye. With Sodium citrate is the same? Before lye?

Dahila, I was discounting enough water from my lye water to dissolve my sodium citrate and then mixing the solution into my oils before adding the lye water. I read somewhere that you could just dissolve the sodium citrate in your water before adding the lye as there shouldn't be a reaction since the sodium citrate is a byproduct of the CA/Lye reaction. (might have got that from this thread).

So, I made a batch yesterday and dissolved the sodium citrate in my water before adding the lye. No problems.
 

DeeAnna

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I agree w Patrick. Sodium citrate is a salt, just like sodium chloride (table salt), and some people add a bit of table salt to their recipe for hardness. Dissolve it in the water before lye.
 
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Dahila

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thank you Patrick and DeeAnna, I thought it should be added as I had with CA, thank you so much for confirming it:))
 
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I'm really glad so many people have been trying this and optimizing this method. I think I'm going to do it like Dee has with a 40% solution next time. It just seems to make more sense and be less of a pain.
 
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Yes, Nev, TEG is right. I wanted to have a way to use citric acid that wouldnt involve adding extra lye. Lye (NaOH) is a pretty expensive and very strong base. Baking soda is much less expensive and just as effective in this case for neutralizing citric acid so it made sense to make up the sodium citrate in this way!
 
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DeeAnna

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Annnnnddddd, as if Effy's and Galaxy's reasons aren't sufficient, I want to add .... many good scientists and engineers also subscribe to the theory "If it ain't broke, fix it anyways".

:mrgreen:
 

commoncenz

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Annnnnddddd, as if Effy's and Galaxy's reasons aren't sufficient, I want to add .... many good scientists and engineers also subscribe to the theory "If it ain't broke, fix it anyways".

:mrgreen:

LMAO .. I spent 6 years in the U.S. Navy as an electronics technician. Many times we took a similar approach in order to get a little down time. Pull a module unsolder a component and replace it with a new one. Make sure to take your time so that you miss PT (physical training) that day. :shh:
 

DeeAnna

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I was hoping some of y'all would get the geeky humor thing. :)

a599a3e08c70e3c87811d73f209f265b.jpg
 

Dahila

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Ha today was my day for Sodium Citrate, I had copy Commoncenz
Teresa all my pots are lagostino so no reaction to CA and BS)
The rest of pics are the process. I ended up with 298 g of SC.
400 ml water weight 340 g
I made it it a fine powder so I am ready to rock, Thank you Galaxy, DeeAnna, and Commoncenz:)) Next time I will make double portion .
I am going to try 2% of my total oils which will be 30 grams (1500 g total oils) I hope I am not off with my calculation
I had done the search on Health Canada and they do not like CA but the sodium citrate is accepted;)) It is for Canadians , we have here:)

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DSCN4533_003.jpg


DSCN4534_004.jpg


DSCN4535_005.jpg
 
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DeeAnna

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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.

19 Nov 2016 update: I found out what the problem was. Other soapers bought commercial sodium citrate and did not report any problems with their liquid soap breaking. After some thought, I realized my homemade sodium citrate solution had to have extra baking soda or citric acid in it. Either of these ingredients would have caused my soap to break.

The solution to this problem is to add a pinch of one ingredient (say citric acid) and see if the mixture starts to fizz again. If it fizzes, then let the fizzing stop naturally, add another pinch of citric acid, let it fizz, and repeat until the last pinch causes no fizzing.

If the mixture doesn't fizz with an added pinch of citric acid, then add a pinch of baking soda and see if that fizzes. If so, then let the fizzing stop naturally, add another pinch of baking soda, let the mixture fizz, and so on until no fizzing happens.

The key is to not get in a hurry -- add a little bit at a time so when the fizzing finally ends, the mixture is as close to pure sodium citrate and water as possible with very little extra citric acid or baking soda. If you overshoot, you could add a bit of the other ingredient to balance things more precisely.
 
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