Sodium Citrate vs EDTA

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BrewerGeorge

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Given that EDTA is both a chelator and helps reduce rancidity, I would guess that most consider it superior to sodium citrate, yes?

So how superior? Say you've got most of a pound of sodium citrate, would you stop using it and get some EDTA instead?

I'd like to start using EDTA, but I don't want to abandon the sodium citrate - one can only make so much cheese sauce. At around 15g per batch of soap, it will last me about 25 more batches and take me two years to get through.

What would you do?
 
If it helps, in my notes I have the following info jotted down (they are based on tests done by Dr. Kevin Dunn):

-EDTA alone works best for both soap scum and DOS
-Citrate alone is half as good as EDTA for soap scum and has no effect on DOS
-A combo of BHT and EDTA are excellent for soap scum and good to prevent DOS
-A combo of BHT and citrate are half as good for soap scum as EDTA, but the best to prevent DOS

I've never used sodium citrate in my soap myself, although I do have a small 2oz packet of it from Lotioncrafters that I bought to test out in it, but with all my other projects going on lately, it's still sitting in the corner. :lol: I've been using tetrasodium edta in my soap for a few years now, though, and I love it. Since it works so well for me, I've been thinking of sacrificing the sodium citrate to mac 'n cheese instead (I read your thread on that with great interest!).

Since sodium citrate has an indefinite shelf life as long as it is stored properly, I'd personally would have no qualms about saving it for mac 'n cheese and buying some edta for my soap. But that's just me.


IrishLass :)
 
I am pretty confident that citrate also works to prevent rancidity (DOS) as well as reduce soap scum. The mechanism of how it operates is similar to EDTA.

I agree that Dunn reported citrate didn't help against DOS, but he was using (speaking from memory here) citrate at a low dose -- I think something like 1 part per thousand (0.1%) or thereabouts. From listening to soapers who use citrate, they're saying it does protect against rancidity and soap scum -- but they're using quite a bit more citrate than Dunn did. I think the dosage difference is the reason why his results were different than what soapers are seeing.

I have sodium citrate (thanks to BG's info about cheese sauce!) and EDTA, but I have only used EDTA in my soap. You're right, BG, a little sodium citrate goes a long way whether in cooking or in soaping!
 
I assume you're taking about citrate and EDTA? If so, you're the second person to ask about this in about as many days. I'll ask you the same question I asked the other person -- is there something you've read that suggests both are more useful compared to one or the other?

I recommend one or the other, but not both. If you want to add another additive, add an antioxidant instead. See IL's post above.
 
I assume you're taking about citrate and EDTA? If so, you're the second person to ask about this in about as many days. I'll ask you the same question I asked the other person -- is there something you've read that suggests both are more useful compared to one or the other?

I recommend one or the other, but not both. If you want to add another additive, add an antioxidant instead. See IL's post above.

No, I did not read anything suggesting that adding both at the same time was beneficial in any way, which is why I asked if they could be used at the same time. I will refrain from using both in the same bar of soap.

The reason I bought both is that my s.o. is more concerned about 'scary' souding chemicals than I am and I will probably not use EDTA in any soap that she will use. Plus, they are both dirt cheap and having both on hand is a no-brainer.
 
Beardguy -- I suppose you could try using both chelators if you're of the opinion "more is better" but I have to say I personally am leery of that. Chelators and antioxidants are powerful chemicals and using them improperly can have unintended consequences. For example I know it is possible to accelerate rancidity by adding more antioxidant than is recommended -- exactly the opposite of what an antioxidant is supposed to do.

Newbie -- As I mentioned earlier, I am pretty sure Dunn used citrate at a very low dose (0.1%) and he didn't think it worked too well. Maybe he's done tests with higher % citrate since the report I read? Soapers who are using citrate at 1% or higher don't seem to have problems with rancidity (DOS), however, at least not problems they're willing to mention. It's been talked about so much on SMF that I think someone by now would have reported "it works for soap scum but I still get DOS" or something like that, if citrate at higher doses didn't work to prevent rancidity.
 
I haven't had any issues with using citrate to date. No complaints from anyone using it. We had an extremely humid summer last year and I found some of my soap sweating like it was raining. I had to toss more last summer than in the rest of my the 7 years of soaping combined. Most was years-old soap, pre-citrate, but I did find some spots on my citrate bars. However, the conditions were rather extreme so I don't think that reflects poorly on the citrate as helping prevent DOS. In fact, I think it reflects rather well that I didn't have to destroy my entire "inventory." (I quote there because I don't sell.)
 
I started using EDTA about a year ago and I LOVE it. I've noticed a significant decrease in soap scum in my shower and a difference in how the soap rinses off my skin. I've never used citrate when making soap but I have a bar from a swap that includes citrate (I don't know the use rate in their batch). So I used them side by side to compare and I prefer the feel of EDTA over the citrate. Soap scum build up in the shower appeared to be the same for both though.

It might be worth it to get a small amount of EDTA and make a 1 lb batch. Then you can decide which you prefer. Lotion Crafter sells 1 oz for $2.95 so, depending on shipping, it shouldn't be a costly investment.
 
Dunn's findings were that SC + BHT are the best; BHT + EDTA or EDTA + ROE were about equallly second best for preventing DOS.

As for preventing soap scum, I currently use the EDTA + ROE combo because I don't have to alter my lye calculations.

If I had all that SC, I'd probably buy some BHT and see how they work together since Dunn reported that they are the best combination.
 
I've used EDTA in my last few batches and I haven't had a chance to use them up to compare how they lather in our hard water but I wanted to know, is there a detriment, apart from waste, from using a higher percentage of EDTA (let's say 2-3 % instead of 0.5 %) ? I don't have the most precise of scale and I don't do huge batches (the biggest I've done is 1kg oils and that didn't fit my tiny loaf mold), so even if I shoot for 0.5 %, due to the scale, I might overshoot that target by a non negligeable margin some times.
 
The entire range of suggested dosages I've found is what Earlene reported -- 0.05% to 4%. The typical dosage used is around 0.5%. I explain all this in my article.

I personally have tried 1% to 3% and found the extra EDTA is not helpful. EDTA also reacts with the lye so larger amounts will cause the soap batter to have a pudding like texture that can be hard to work with.

I strongly suggest sticking with no more than 0.5% max for soap scum control and rancidity reduction. If a little works as well as more, then stick with the lowest effective dosage.

If your scale is too imprecise to measure this correctly as powder, then make a dilute solution of EDTA so you have bigger weights to measure. That will reduce the margin of error. Or put a new scale in your budget?
 
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