What is sodium citrate?

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jennyannlowe

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What is sodium citrate?
What is it used for?
I know I can read about it online but I don't trust it all the time.
Same question for rosin.
 
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Seawolfe

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If you scroll to the bottom of this page you will see other threads that talk about sodium citrate.

Sodium (or potassium) citrate help with a lye based solid or liquid soaps lathering abilities and prevent soap scum. Its benefits are more pronounced the harder your household water is.

Some people add sodium citrate to the soap mixture (not sure at which stage), others (like myself) add citric acid to the water before the lye goes in. Citric Acid + NaOH (or KOH) produces sodium (or potassium) citrate. However this reaction uses up some of the lye, so you have to do a calculation to add more lye than the soap calculator calls for in order to compensate for this - otherwise the superfat would be higher than you want.

Edit to add: I have no idea about rosin, Ive seen recipes that call for it, but Im not clear what its role is, hopefully someone smarter than I will chime in.
 

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cmzaha

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I masterbatch a 50/50 citric acid solution because I hate adding citric acid to my lye water and I can just add it into my batch oils. Just like masterbatch lye you double the required amount and deduct the other half from your water requirement. Add in the extra necessary lye. Citric acid can be added from 1-3% of your batch total. I find if I am using a high percentage of liquid oils it works better for me to use 2% or my soap are a little soft. My lard and tallow soaps I go with the 2.5%.
For my 2600 gram batches I would use 65 grams citric acid/130 grams 50/50 citric solution (2600*2.5%)
65g citric * .624 = 40g extra lye needed for chelating. If DeeAnna pops up she can explain it much better
 

joy.

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I masterbatch a 50/50 citric acid solution because I hate adding citric acid to my lye water and I can just add it into my batch oils. Just like masterbatch lye you double the required amount and deduct the other half from your water requirement. Add in the extra necessary lye. Citric acid can be added from 1-3% of your batch total. I find if I am using a high percentage of liquid oils it works better for me to use 2% or my soap are a little soft. My lard and tallow soaps I go with the 2.5%.
For my 2600 gram batches I would use 65 grams citric acid/130 grams 50/50 citric solution (2600*2.5%)
65g citric * .624 = 40g extra lye needed for chelating. If DeeAnna pops up she can explain it much better
When you masterbatch your sodium citrate, are you doubling the citric acid + sodium hydroxide to get your water amount? How are you storing the solution?
 

rosche

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As far as I know,sodium citrate can boost lather, be chelating agent and prevent DOS.

But I have question. If I already add EDTA in the soap, it's fine to also add sodium citrate or will it be a waste?
 

DeeAnna

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It's another chelator, Jenny, like citrate. Tetrasodium EDTA (EthyleneDiamine TetraAcetate). Citrate and EDTA do two things for soap -- Either one will reduce the sticky soap scum that happens when you use lye soap with tap water. Either one will also bind up (the fancy word is "chelate") certain kinds of metals that cause rancidity (DOS) in your soap.
 
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rosche

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Awww, I already buy both EDTA and sodium citrate. Hahaha. But I guess EDTA is easier to use since kevin dunn said sodium citrate should be combined with BHT in order to get best result against DOS, afaik.
 

DeeAnna

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Dunn did say you can combine a chelator with an antioxidant to effectively reduce the chance of rancidity (DOS), but you do not HAVE to.

He recommended a combination of (BHT + citrate) as being the most effective of all the combinations he tried. Other effective treatments were EDTA alone or (EDTA + rosemary oleoresin) or (EDTA + citrate). What did not work for Dunn in his experiments was the combination of (BHT + citrate) or using citrate alone.

That appears to remove the use of citrate alone as an effective prevention against rancidity, but keep in mind that Dunn was doing a limited set of experiments under controlled conditions. Since his report about this work, people are adapting that information to suit their needs. That gives us a broader field of information to look at, so we should not only look at Dunn's experimental findings, but we also need to look at whether real world soapers are getting similar results in their real-world soap.

What people are seeing in real life generally support his findings, except it looks like citrate alone may be more effective in preventing rancidity than Dunn predicted. Soapers are using citrate in higher dosages than he did in his experiments, however, and that might be the key reason for the difference.

So don't eliminate the option to use citrate alone -- it may work better than you think. In addition, citrate is an inexpensive chemical that can be made from citric acid and a bit of lye or other alkali. Of all the chemicals that can be used to control rancidity, citrate is an easily available and inexpensive treatment available to soapers worldwide. For example, I can go to my small rural grocery store and buy enough citric acid to treat many batches of soap. I cannot buy BHT, EDTA, ROE, etc. in my local area.
 
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LazyUmbrella

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is it just me, or does all this talk about sodium citrate put you in the mood for lemonade? :)
 

jennyannlowe

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Using this recipe:
lye concentration 30%
500 grams oil weight

Olive 35%
lard 20%
coconut oil 25%
castor 10%
cocoa butter 10%

then citric acid 10g plus adding 6.24g of extra lye to compensate
Sodium lactate 10g

i add the citric acid to the water before I add the lye.
then I add the sodium lactate to the cooled lye water

I understood that adding these will increase hardness, promote lather in hard water and decrease soap scum.
So far I have not noticed any adverse effects however my soap has just begun to cure. My question is...is it okay to add these items to every batch at about 10g PPO each?

oBviously once they are cured, I'll do some testing. but what do you guys think?

And please remember that I am newbie and I havent yet earned my honorary soap makers chemistry degree yet so sometimes the math makes my head hurt. So..opinions in SPT? (stupid peoples terms) LOL just kidding.
 

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