Sodium citrate from baking soda and citric acid

[Dr.J]

Hi Theresa did anyone ever answer your question as to where you can buy sodium citrate in a store? Making your is all very well but i really dont want to if i dont have to. Chemistry was never my strong suit

I've bought it on Amazon before, but ever since I found it at The Chemistry Store I buy from there exclusively. The Chemistry Store also carries many other soaping ingredients.

 

[Gaisy59]

I've bought it on Amazon before, but ever since I found it at The Chemistry Store I buy from there exclusively. The Chemistry Store also carries many other soaping ingredients.

Awesome thanks for the info!

 

[Hils67]

Hey, Teresa, good save! After a cuppa joe this morning, I rummaged around, found my geek hat and paraphernalia, and re-read Galaxy's original post. She did all the math for us already!

Galaxy's original recipe:

400 g distilled water
200 g citric acid
263 g baking soda

After following her procedure for mixing this up, the chemical reaction will create 268 g trisodium citrate (aka sodium citrate). When you get the baking soda all dissolved and everything stops fizzing, you'll have 268 g sodium citrate plus some water and perhaps a bit of leftover baking soda.

If you don't want to evaporate the citrate to a dry powder, I would suggest making a 50% sodium citrate solution. To do this:

Weigh the solution you've just made. The weight of water in the solution after everything is all reacted will be:
After-the-reaction water weight = Total solution weight - 268 g of sodium citrate

If you add enough extra water to this mixture so the total water is equal to 268 g, then you will have a 50% solution of sodium citrate. In other words:
Water to add to make a 50% solution = 268 g - After-the-reaction water weight

***

To scale this recipe up or down, you can use this relationship:

1 gram citric acid plus 1.31 g baking soda gives you 1.34 g sodium citrate.

***

To use, figure the weight of pure sodium citrate you want to add to your soap batch. Since every gram of your solution has only 0.5 g of citrate, use TWO TIMES that weight when measuring out your 50% sodium citrate solution.

What dosage of citrate to use in soap? A typical dosage for citric acid is about 1% ppo. The equivalent dosage of sodium citrate is 1.3% ppo. You can do 2 or 3 times that amount, if needed.

I know this is an old post, but thank you so much for explaining this so clearly. I was researching how to use citric acid as a chelation and came across this post...brilliant!!

 

[Mobjack Bay]

I finally made a masterbatch of 33% sodium citrate using this method. I decided to try it because I already have a large bag of CA that I stopped using because crystals were forming on the top of my soap, even when I dropped down to 1%. For the MB, I used 200 g CA, 263 g of baking soda and 600 g of water. I mixed everything at room temp and was amazed that it fizzed for at least 7 hours (at which point I went to bed). With no heat applied, I will need to let some of the water evaporate to get the SC concentration up to 33%. I settled on 33% rather than 40% to keep the math as close to brainless as possible.

eta: I’m happy to report that I’m not seeing crystals on the soaps I made with the sodium citrate MB.

 

[myriad]

I tried the BS and CA neutralization experiment in water and wow, it does bubble for a good while!

Baking soda has to be imported into my country, so I'm curious about creating citrate from other common household bases, like washing soda and potash. (Jackie Thompson's Liquid Soapmaking, for example, uses potash to make citrate, but doesn't explain the math). I can't find this info anywhere on the web, can anyone help?

From the OP, if:
1 gram of citric acid is neutralized with 1.3124 grams of baking soda

Then:
1 gram of citric acid is neutralized with ?? grams of washing soda (sodium carbonate) or
1 gram of citric acid is neutralized with ?? grams of potash (potassium carbonate)

 

[LynetteO]

 

[The_Phoenix]

I finally made a masterbatch of 33% sodium citrate using this method. I decided to try it because I already have a large bag of CA that I stopped using because crystals were forming on the top of my soap, even when I dropped down to 1%. For the MB, I used 200 g CA, 263 g of baking soda and 600 g of water. I mixed everything at room temp and was amazed that it fizzed for at least 7 hours (at which point I went to bed). With no heat applied, I will need to let some of the water evaporate to get the SC concentration up to 33%. I settled on 33% rather than 40% to keep the math as close to brainless as possible.

eta: I’m happy to report that I’m not seeing crystals on the soaps I made with the sodium citrate MB.

Since this thread just today got a shot in the arm…

I, too, experienced crystallization on my soap tops when I used CA and switched to SC a few minutes this ago, I want to make my own as you did.

 

[Mobjack Bay]

Since this thread just today got a shot in the arm…

I, too, experienced crystallization on my soap tops when I used CA and switched to SC a few minutes this ago, I want to make my own as you did.

I’ve made two or three batches now and it’s working well. I just this past weekend started using 1.5% SC (based on oil weight) and didn’t get any crystals.

 

[weirdchylde]

If you evaporate off the water and are left with a powder then you would just treat is as any dry additive and just dissolve it in the minimum amount of water and add it into your lye solution (after the lye water is prepped.). You could even add it at trace if you wanted to.

Alternatively, you can keep it as a solution. I wouldn't prep the lye water in it though since its already going to have a lot of dissolved salt in it. Thats going to make it more difficult to dissolve the sodium hydroxide in it. Just discount your water when you make your lye solution for it.

You can concentrate this solution to quite a bit more than the original solution I made. Just keep in mind that if you evaporate off too much, you'll get some sodium citrate to come out of solution once it cools. I'm not sure how much you can concentrate it b/c I haven't done it yet but, I think I might make it as a concentrated solution next time instead of the powder. I'll report back when I do.

I'm definitely still tweaking it but, I really love using the stuff!

I wanted to clarify, @galaxyMLP, since I've never used citric acid or sodium citrate before. In @DeeAnna's writeup on Sodium/Potassium citrate powder, she mentions dissolving it in 2 x water by weight. Do I then discount that dissolving water from the total water weight as well, like you said to if we used a solution? I'm having a bit of trouble figuring that out and I've pored over this thread a few times to get my head wrapped around this new step in my soap-making.

I just moved to a village with pretty hard water and am learning as I go how to adapt! Thanks for all of this science-ing, your geek-out is a boon to all of us!

I also have another question about adding the Sodium Citrate for my hard water situation, while keeping the soap still useful for not-so-hard water. I have friends and family where I used to live who love my soap and I don't want to make double batches with and without for just that reason. If I add sodium citrate to my soap, say around 2%, will that still be ok for those with a softer water? What would be the consequences of adding too much SC with soft water?

 

[isabel.carrillo]

So, I've seen posts about sodium citrate all over the place (for chelating) and I bought myself some citric acid to add it to my soaps.

I've seen alot of people talking about adding extra lye to make their sodium citrate solution in their lye water. Since I'm forgetful when it comes to soaping, I kinda wanted to skip a math step. I wanted to make sodium citrate itself (dry powder).

I decided to use baking soda because its cheaper than sodium hydroxide but is also a base. The same can be done with washing soda if you wanted to (please note the amounts for neutralization with washing soda will be different. If you want to do that, just post here and I'll do the math for you)!

After doing some math:
1 gram of citric acid (CA) is neutralized with 1.3124 grams of baking soda (BS).

1. I weighed out 200 g of CA and 263 g BS.

2. I added 400 ml of water to a pot and added the CA till dissolved. Then I added the BS slowly!! Remember vinegar + baking soda (or even bath bombs) it with fizz up! Let it stop fizzing before proceeding. You need to stir to stop it from overflowing. I also tested the pH w/ pH paper. I wanted it to be at least 7-8. I didn't want it to be acidic b/c that would up my superfat when I used it in soap.

3. I boiled it until the water was evaporated (maybe an hour). During the evaporation, for the last bit, it got syrup like. Then it started to cake the bottom of the pot. I recomend using a steel pot for this b/c you will get it caked on the bottom and may need to scrape some of it off.

The theoretical yield (amount of sodium citrate I should end up with) for the amount of CA and BS I originally used was 268 g. I got 321 g because I couldn't get all the water to evaporate. Not bad though.

Picture time:

Boiling:

View attachment 15897

Finished and labeled

Hi! I found your post and have done sodium citrate =)
Before making soap with it, I would like to test it's ph. Could anyone tell me, please, how much sodium citrate I have add to 100m of water for the test? Thank you!!!! Isabel

 

[CLMP]

This is really good info thanks so much I've been wanting to try these methods.

 

[AliOop]

Hi! I found your post and have done sodium citrate =)
Before making soap with it, I would like to test it's ph. Could anyone tell me, please, how much sodium citrate I have add to 100m of water for the test? Thank you!!!! Isabel

Testing pH is always done with a 10% solution.

However, I would like to ask why you want to pH test this before using it? Don't believe the tales you may hear or read where people supposedly lowered the pH of their soap to anything much below 9. The pH strips are extremely inaccurate, by 2 points or more. Plus, most of the time, they aren't being used correctly. I've seen videos where the strips are laid directly on wet soap, for instance. That will never give an accurate reading.

If tested correctly (with a pH tester, not the strips, and in a solution of 90% water and 10% soap), you soap will always be high in pH. Anything below 9 pH will start to break apart and be an oily, gooey mess, rather than a firm bar of soap.

Also, the pH of the soap will not tell you whether it is lye-heavy. The zap test is best for that.

 

[Servant4Christ]

I know this is an older post, but I had so much fun trying this out today! I weighed my citric acid and baking soda into a large glass Pyrex measuring pitcher, then slowly added distilled water until all the fizz stopped. I was surprised at how COLD the glass pitcher got!
Next, I cooked the dissolved liquid on my stovetop in a wide shallow stainless pan until most of the water was gone. Seriously, the mixture suddenly does a sort of foamy reaction right at the end so that's when I cut the heat off and transferred everything to a glass casserole dish and moved it to the oven. I finished dehydrating everything at 200°F, checking on it every once in a while to scrape it up and spread it out with a wide spatula. When it was fully dried and cool, I powdered it in my DIY coffee grinder and transfered to a glass mason jar to store. Final weight was 260g.

 

[DeeAnna]

I was reading earlier posts in this thread. In one, Isabel was wondering if they could dissolve some of their sodium citrate in water and test the pH to learn if it was pure enough. It doesn't work that way -- the pH test alone cannot measure purity.

People who don't have practical experience in chemistry often think pH is able to measure properties like purity or concentration or excess lye or whatever. It can't.

And even if it could, the pH test isn't very accurate if one uses test strips like most people use. Testing pH to a whole pH unit ... or even to 0.5 pH unit ... like most people do will not give you precision results. Sure ... you'll get some kind of result from a test strip or cheap pH meter, but you honestly won't know what that result really means.