Sodium citrate from baking soda and citric acid

[The Efficacious Gentleman]

I wonder if it is akin to when we try to add other things to a finished LS? If we add an EO after we make the soap paste, it doesn't always stay well mixed. Of course, that could be an oil and water problem, but the soap should act as a mild emulsifier. Maybe the key to chelating with SC is that it is in the product itself?

 

[DeeAnna]

Perhaps you're right, Gent, but if so I'm going to have to seriously rethink my mental picture of the process. The chelating activity that reduces soap scum should occur when the soap is in solution with the water on your skin as you bathe. That process needs to happen very quickly, thus the chelants (EDTA, citrate) have to be able to mobilize fast to do their job.

I'll do some more digging.

 

[The Efficacious Gentleman]

Perhaps you're right, Gent, but if so I'm going to have to seriously rethink my mental picture of the process. The chelating activity that reduces soap scum should occur when the soap is in solution with the water on your skin as you bathe. That process needs to happen very quickly, thus the chelants (EDTA, citrate) have to be able to mobilize fast to do their job.

I'll do some more digging.

Any more joy playing with the home made SC in soaps?

 

[DeeAnna]

Hey there, Gent -- Nope, I'm not getting any results from digging into the chemistry, nor has anyone else offered any suggestions to enlighten my ignorance.

The only odd bit I have uncovered recently is that when Kevin Dunn did tests to find his tests of effective chelators and antioxidants for soap, he learned sodium citrate (on its own) was not at all effective in controlling color change in his test soaps. A mix of citrate and rosemary oleoresin (ROE) worked worse than ROE alone or no treatment at all. Only when citrate was added with BHT did citrate add something positive to the party. Not sure what that is telling me, but it's something.

The project is still on my to-do list, but stalled for the moment. :think:

 

[kumudini]

Thanks for the bump folks, it reminded me that I still needed to make it. It's on my stove now, boiling away.

 

[kumudini]

I finished making the sodium citrate and drying it to my satisfaction. I was thinking, it's too much work but it helps me save on the lye, not that it's super expensive but since I'm running out faster. Anyways, the light bulb goes off! If according to DeeAnna I need 6.24 grams of lye to neutralize 10 grams CA, it appears from Galaxy's math that I would need 13 grams of sodium bicarbonate for the same amount of CA. Why don't I just add the extra base as bicarb instead of lye and be done with it? It's just as handy as CA is in my soaping area and math is not a problem for me. So, what you say DeeAnna, can I just add 13 grams of sodium bicarbonate to every 10 grams of citric acid in my recipes?

 

[commoncenz]

how would you make sure that the bicarb interacted with the CA and not the lye?

 

[kumudini]

how would you make sure that the bicarb interacted with the CA and not the lye?

Brilliant question, I'm sure I can add both CA and bicarbonate to water and wait till fizzing is done, then add the solution to the recipe. But my google search revealed that the end product of a bicarbonate and lye reaction would be the infamous soda ash, which means I absolutely have to wait until all the fizzing is gone, which hopefully means that the CO2 is out of the equation and won't cause any additional ashing.

 

[DeeAnna]

I think your math is correct, but Patrick has cut to the heart of the matter. You'd have to wait long enough to let the citric-bicarbonate reaction to end before putting your NaOH into the mix. The citric-bicarbonate reaction is going to be a slow step, even if you add heat to drive the process. The reaction of citric acid with NaOH is going to be near instantaneous. I guess the only reason why I'd put up with doing the bicarbonate reaction as you propose is only if the cost of NaOH was as dear as unicorn horns.

 

[kumudini]

I agree DeeAnna, after I finish this batch of sodium citrate I'm just going to use EDTA. Again, not that the lye is expensive but I don't want to run out before my next order.

 

[hmlove1218]

Galaxy's original recipe:

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

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.

I'm trying to wrap my brain around this as all these numbers have made my head spin lol.

1) How did you arrive at a total of 268 g SC after the reaction for above recipe?
2) After the reaction, subtract SC from total weight to get current water weight and then add water (if needed) to result in 50/50 solution, yes? If there's too much water, just let some of the water evaporate until the correct weight?

If this has already been covered, I apologize. I got to page 8 and my brain fizzled out lol.

 

[DeeAnna]

1) How did you arrive at a total of 268 g SC after the reaction for above recipe?

This weight is based on translating the chemical formula for this reaction. Since some of the final product is carbon dioxide gas, some of the starting weight ends up in the air. So you can't add up the starting weights to get the ending weight.

2) ....If there's too much water, just let some of the water evaporate until the correct weight?

If my recollection is accurate, I don't think you will have too much water if you follow Galaxy's recipe. But yes that would work to let some evaporeate.

 

[galaxyMLP]

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!

 

[hmlove1218]

Question. I mixed it up following the original recipe and something has settled out to the bottom but the rest is clear. If I shake it, it starts reacting again. Should I keep shaking it until all is dissolved?

 

[galaxyMLP]

Question. I mixed it up following the original recipe and something has settled out to the bottom but the rest is clear. If I shake it, it starts reacting again. Should I keep shaking it until all is dissolved?

Yep!! Keep going till there are no bubbles at all any more. Then, add in some baking soda (a pinch!) after its stopped fizzing when you shake it. If it starts fizzing again, add more baking soda pinch by pinch till it stops. If it doesn't fizz at all youre good to go. Thats just the easiest way to make sure all of your citric acid is reacted. The other way is to pH test it. Once you're at or above 8, you're good.

 

[hmlove1218]

Thanks! Don't have any pH strips, so I'll just go with the fizzy test lol

 

[Gaisy59]

Sodium Citrate

I started to do that, but thought that would defeat the purpose of cooking it. But, I feel better that you've made the suggestion, DeeAnna. Thanks. I'll go toss some distilled water in it and see what happens. If it's a total mess-up, where do I buy sodium citrate?

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

 

[CaraBou]

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

You can order it online through eBay or Amazon - just google it. I order food grade, that way I can melt hard cheeses, too

 

[The Efficacious Gentleman]

If you can't find it and don't want to make a big batch of it, you can add the citric acid in and calculate how much lye you need to turn it in to citrate.

Oil weight calculates to how much citric acid you need. Amount of citric acid calculates directly to the extra lye that you need.

It's not actually that complicated, especially if you always make the same sized batches as you only need to get the numbers once and write them down, and people here are more than willing to check your maths if you are unsure.

 

[Gaisy59]

Calculating citric acid

If you can't find it and don't want to make a big batch of it, you can add the citric acid in and calculate how much lye you need to turn it in to citrate.

Oil weight calculates to how much citric acid you need. Amount of citric acid calculates directly to the extra lye that you need.

It's not actually that complicated, especially if you always make the same sized batches as you only need to get the numbers once and write them down, and people here are more than willing to check your maths if you are unsure.

Thank you very much! I have ordered the same product that Irish Las has but i will also take you up on the citric acid calculations offer. I will first find a recipe i will stick with and then ask for your assistance.