De-ionised water & EDTA questions

[hozhed]

They're coming from the water you bathe/shower in.

Sonya,....you mean the metals affect the soap at the point of use? In what way?

 

[not_ally]

Hoz, those of us who have hard water - that with lots of chemicals/metal - coming out of the tap end up with lots of soap scum when we use our handmade soap, the oils (I think) combine with the chemical stuff and create scum which, while not dangerous or otherwise unhealthy, is ugly and messy. Commercial soaps include lots of chemicals to deal with that, I guess it would be hard to sell them otherwise, ours don't typically.

I think some oils are worse for that, including (eg and unfortunately) lard, which I love and use in large proportions. Chelators, EDTA is the best, help with that by binding to the scum and carrying it down the drain instead of having it stick to the tub or you when you are bathing. I'm sure DeeAnna can give you a better explanation, but that's the layman's version!

 

[hozhed]

Hoz, those of us who have hard water - that with lots of chemicals/metal - coming out of the tap end up with lots of soap scum when we use our handmade soap, the oils (I think) combine with the chemical stuff and create scum which, while not dangerous or otherwise unhealthy, is ugly and messy. Commercial soaps include lots of chemicals to deal with that, I guess it would be hard to sell them otherwise, ours don't typically.

I think some oils are worse for that, including (eg and unfortunately) lard, which I love and use in large proportions. Chelators, EDTA is the best, help with that by binding to the scum and carrying it down the drain instead of having it stick to the tub or you when you are bathing. I'm sure DeeAnna can give you a better explanation, but that's the layman's version!

Ok, that makes sense. I wonder if that's why some here make "salt bars"? We use EDTA and other chelants where I work to tie up metals because they inhibit the bleaching process which is not good. I wonder if I can get a deal on EDTA ,since we buy it by the train car load???

 

[not_ally]

I've never considered salt as something which might help with chelation, is there some kind of chemistry there that would lead to that? As you can probably tell, I am not good at that stuff, although I find it interesting and try hard to understand.

EDTA is not super cheap, I think it is about $15 for a lb on ebay, but it goes a pretty long way for me since I am a hobbyist. I haven't really worked out the cost ppo or anything, just mix it up in those 16 oz squeezies, so don't have to mix it that often, but it's not comparable to using really expensive stuff like FOs. I bet you could get it cheaper through work, though.

 

[DeeAnna]

"...why use a chelant for soap if you use distilled water? Where are the metals coming from?..."

What the others are saying is all spot-on, Hozhed.

Metal ions such as copper (Ca++) can cause DOS/rancidity in a finished soap bar. These metal ions are catalysts for rancidity, in that they greatly increase the speed of the chemical reactions that cause fat to go rancid.

One way to minimize these metal contaminants is to avoid using ingredients that contain them. For example, I use distilled water to make my soap because it has zero or only a trace of metallic impurities. Tap/drinking/spring water may or may not contain metals that trigger DOS, which is why some people have problems using tap water in soap and others don't. You can't tell if there are metallic impurities in tap water unless you test for them.

But other ingredients, including most soaping fats, normally contain some metallic impurities, so a soaper can only do so much to avoid this problem. It's good to have a backup plan, and one way to deal with metals that sneak their way into finished soap is to use a chelator such as EDTA. A chelator has chemical "claws" that can latch onto and immobilize certain types of ions. You need only trace amounts of EDTA for this purpose -- just enough to bind up those pesky trace metals lurking within the soap bar.

Another issue that chelators can help with is to bind up the metals in your tap water that react with soap to make hard water scum when you're using the soap in the bath or shower. This scum feels icky on the skin, and it reduces the lather of the soap -- if the soap is being forced to create scum, it can't make nice suds! Metal ions like calcium and magnesium are the culprits here.

Softening the water helps a lot because typical home water softeners replacing calcium and magnesium ions with sodium ions that don't cause trouble. If you don't have soft water, then adding a chelator like EDTA to your soap can help reduce hard water scum. A higher dose of EDTA is going to be better for this purpose because the EDTA has to to chelate the metal ions in the water that's mixing with the soap on your washcloth. A chelator in your soap might not reduce soap scum entirely, especially if your water is super hard, but it will certainly help.

On a related note, there's more about this here: http://www.soapmakingforum.com/showthread.php?p=509320 Jump to post 39 to skip to the EDTA part of this thread.

 

[hozhed]

"...why use a chelant for soap if you use distilled water? Where are the metals coming from?..."

What the others are saying is all spot-on, Hozhed.

Metal ions such as copper (Ca++) can cause DOS/rancidity in a finished soap bar. These metal ions are catalysts for rancidity, in that they greatly increase the speed of the chemical reactions that cause fat to go rancid.

One way to minimize these metal contaminants is to avoid using ingredients that contain them. For example, I use distilled water to make my soap because it has zero or only a trace of metallic impurities. Tap/drinking/spring water may or may not contain metals that trigger DOS, which is why some people have problems using tap water in soap and others don't. You can't tell if there are metallic impurities in tap water unless you test for them.

But other ingredients, including most soaping fats, normally contain some metallic impurities, so a soaper can only do so much to avoid this problem. It's good to have a backup plan, and one way to deal with metals that sneak their way into finished soap is to use a chelator such as EDTA. A chelator has chemical "claws" that can latch onto and immobilize certain types of ions. You need only trace amounts of EDTA for this purpose -- just enough to bind up those pesky trace metals lurking within the soap bar.

Another issue that chelators can help with is to bind up the metals in your tap water that react with soap to make hard water scum when you're using the soap in the bath or shower. This scum feels icky on the skin, and it reduces the lather of the soap -- if the soap is being forced to create scum, it can't make nice suds! Metal ions like calcium and magnesium are the culprits here.

Softening the water helps a lot because typical home water softeners replacing calcium and magnesium ions with sodium ions that don't cause trouble. If you don't have soft water, then adding a chelator like EDTA to your soap can help reduce hard water scum. A higher dose of EDTA is going to be better for this purpose because the EDTA has to to chelate the metal ions in the water that's mixing with the soap on your washcloth. A chelator in your soap might not reduce soap scum entirely, especially if your water is super hard, but it will certainly help.

On a related note, there's more about this here: http://www.soapmakingforum.com/showthread.php?p=509320 Jump to post 39 to skip to the EDTA part of this thread.

Excellent DeeAnna, thank you and the rest for the input.

As an aside, chelants are for sure, very effective. I am a papermaker, and we use around 4lb. chelant per TON of wood pulp to tie up metals that inhibit bleaching. Pretty efficient.

 

[DeeAnna]

Salt (table salt, NaCl) cannot act as a chelator -- it just doesn't have the chemical structure to do that kind of job -- so people make salt bars for reasons other than expecting the salt to deal with hard water scum.

 

[not_ally]

Thanks, DeeAnna, you save me from yet another chelation experiment. I am on a lifetime quest to defeat the evil scum, at least as much as possible.

 

[rosche]

Hello everyone. I have the same question as topopfmurrayhill. I see somewhere that Dunn sugesst 0.1% of edta. But it's also combine with 0.1% sodium citrate and BHT.

I hope I'm not OOT but what does the combination of edta and sodium citrate do in soap? Is it better to use both? Or edta only is enough (as chelating agent and water softener and lather booster)

I also read somewhere that edta can be an emulsifier too. Is it true?

 

[DeeAnna]

Kevin Dunn evaluated chelators specifically for reducing rancidity in bar soap, not for reducing soap scum when the soap is being used for bathing. If all you want to do is protect against rancidity/DOS, by all means follow Dunn's recommendations for the dosages of the various chelators and anti-oxidants. Otherwise, kindly re-read the last half of my Post 25 (above), specifically the next to last paragraph.

"...Dunn sugesst 0.1% of edta. But it's also combine with 0.1% sodium citrate and BHT...."

Nooooo .... I am quite sure that is not what Dunn said, at least in his Scientific Soapmaking book. In the book, Dunn only looked at pairing one chelator and one anti-oxidant. And it was EDTA at 0.5%, not 0.1%. Re-check your source?

"...I also read somewhere that edta can be an emulsifier too. Is it true? ..."

Not that I am aware of, and a quick Google search did not bring anything up about this. If you would like a better answer, please provide the source so I have something more to go on.

 

[not_ally]

Rosche, the link that DeeAnna posted in #25 is really helpful. Somewhere it it, TOMH provided a link to the Dunn chapter on this stuff, it is this: http://cavemanchemistry.com/DreadedOrangeSpot-Dunn.pdf

As DeeAnna says, it refers specifically to DOS, but is pretty helpful in that respect.

D, I have another EDTA question for you - aren't you sick and tired of them ? I have been using one of my brine bars regularly at the bathroom sink. The formula is 65% lard, 15% CO, 13% olive, 7% castor, salt as 25% of the water weight. Also .5% EDTA, 3% sodium lactate and the equivalent of 1.5 TB sugar, ie, in a 50/50 sugar solution. All in a batch of 24 oz oils.

So, adding EDTA has been wonderful in terms of dealing with the scum, generally, I have hardly been noticing it these days. It is particularly evident in the sink b/c I use it so often there and the non-EDTA soapies made a big mess. But the scum rings have reappeared, if less badly, with the brine soap. Is it b/c of the extra NaCL, do you think? If so, would upping the EDTA help?

I have just made several batches of salt soap, am wondering if I should be upping the EDTA in those, espec. b/c the salt amts are higher than in brine (80%, 50% and 30% of oils - not water - respectively.)

 

[rosche]

THank you so much for the answer DeeAnna and not_ally. I should learn more >_<

 

[not_ally]

This place is a good one to start! There is so much information and help ....

 

[DeeAnna]

Not_ally -- I don't have a good answer for you. You either have soap scum forming, or you have excess soap or superfat being deposited rather than dissolving in your water. Try an experiment -- If you have a patch of goo on your shower or sink to mess with, let a few drops of your EDTA solution soak on some of the goo for a few minutes. Rinse gently with cold water. The EDTA should dissolve the goo if it really is soap scum. If that is the case, then a higher dose of EDTA might be good to try.

 

[not_ally]

What a great idea, D. Thank you! Will do so and report back later. Sometimes I feel guilty pestering you so much, let me know via PM if you want a break ...

 

[Lion Of Judah]

are there any alternatives to EDTA ?

 

[DeeAnna]

Sodium citrate is also a chelator, Lion.

 

[Lion Of Judah]

"Much thanks for the reply DeeAnna" , i was looking up the other day about EDTA and found some info that made me want to seek out an alternative.
...."Tetrasodium EDTA is a preservative that’s made from the known carcinogen, formaldehyde and sodium cyanide. (see how) It is also a penetration enhancer, meaning it breaks down the skin's protective barrier, going right into your bloodstream. Many companies trying to be "natural" will use Tetrasodium EDTA instead of parabens to preserve their products. In my opinion, Tetrasodium EDTA is just as bad."

so i'm glad that there is a alternative . [ citric acid same thing ?]

 

[DeeAnna]

I don't expect to change your thinking on this matter, but I must respectfully point out that your source of information is a poor one.

***

"... It is also a penetration enhancer, meaning it breaks down the skin's protective barrier, going right into your bloodstream...."

I'd say this study provides more useful and even handed information about the "horrors" of EDTA being a skin penetration enhancer.

Do keep in mind that I'm an engineer first and foremost, and my bent is to give more weight to peer-reviewed studies than internet bloggers. I have no respect for writers such as the one on bubbleandbee.com who make unsubstantiated statements designed to stir up fear and confusion rather than create understanding and respect.

***

"...Tetrasodium EDTA is a preservative that’s made from the known carcinogen, formaldehyde and sodium cyanide..."

Yes, the main chemical process to make EDTA uses chemicals that can injure and even kill. As an engineer who used to work in plants that manufactured useful chemicals, I know that's often the way chemistry works -- you sometimes have to use highly reactive and dangerous chemicals to create certain types of chemicals.

Soap falls in that category too. We use NaOH or KOH -- highly reactive, dangerous chemicals that can quickly injure and even kill -- to make a product that is much more benign and arguably beneficial. Does the character of the lye remain in the soap? No.

Should we then judge the safety and usefulness of soap by the chemicals from which it's made? Some uninformed and fearful people most certainly do believe that to be true -- just check out the various internet bloggers who assert that soap can be made without lye -- here's one example. And still others, such as this one, who issue a blanket warning of "...Make sure it’s [sodium hydroxide] not in any of your skincare!..." But we as soapmakers know better. We respect the lye when we use it ... and enjoy the soap after the lye has been transformed into that beneficial end product.

So moving on to EDTA, is it then correct to think the formaldehyde and cyanide used to make EDTA remain in the finished EDTA? No. But there are quite a few fear-mongering bloggers who say exactly that to stir up controversy and blind loyalty amongst people who would rather be governed by fear than by facts.

***

"...Many companies trying to be "natural" will use Tetrasodium EDTA instead of parabens to preserve their products...."

EDTA is a chelator, not a microbial preservative. Anyone who takes a small amount of time to learn about proper product formulation will not make the mistake of confusing EDTA as a preservative. This is another unsubstantiated claim intended by the blogger to create fear and confusion, not respect and understanding.

***

Use EDTA if you want to. Or don't. It doesn't matter to me. But the koolaid being served by internet bloggers like this one is not a good basis for rational decision making.

 

[Sonya-m]

I think I might love you DeeAnna!! I KNEW you would respond like this, I wanted to but knew you'd do a much better job!