Preferred Chelating Agents

[DeeAnna]

"...should I up the citric acid until I get to the stage of no droplets on the dishes?..."

Even a whole house water softener can't remove all the hard water minerals in water. It is totally unrealistic to expect a tiny bit of chelator in a bar of soap or in a squirt of liquid soap to solve the problem, especially when you're talking about treating water used to wash dishes and clothes.

On top of that, there are consequences to the quality of the soap if you try to load it with an excess of an additive like this. At about 3% citric acid or more, the soap will begin to feel rubbery and citrate salt crystals will form a white efflorescence on the surface of the soap.

"...Will it be harsh on the hands... If I then use this soap in softer water, will there be a problem? Will this feel stripping?..."

I use EDTA, not citrate, but I've not noticed anything like that. You seem to be thinking the use of a chelator will affect the mildness or harshness of the soap itself. You need to look at your basic soap recipe for whether the soap will be harsh to the skin or not. A harsh soap will be harsh whether you use it in hard water or soft. A gentle soap will be gentle regardless of the water.

 

[Nanditasr]

You seem to be thinking the use of a chelator will affect the mildness or harshness of the soap itself. You need to look at your basic soap recipe for whether the soap will be harsh to the skin or not.

Thanks; yes, I was indeed worried that the chelator might affect the mildness or harshness. Actually, I am very happy with the recipe of the soap. Now that you've clarified this, I'll probably tweak it with just a tad more citric acid (maybe increase the 1% to 1.5%).

 

[Shelldybop]

So in the course of my weird and wonderful experiments I seem to have stumbled across something odd... soaps with CA stay wet for longer. Not as in soft while curing, but wet while drying between uses...

For the s***s and giggles, and because I had some lye that I had mixed wrong and didn't want to waste, I made a 20% citrate bar. I HPd with a very conditioning high linoleic recipe and a little rose clay (I am colour coding my endeavours), while that's a pretty extreme % it is waaay more drying than I expected and also still has that wet feel.

Just thought Id share!

 

[Nanditasr]

...soaps with CA stay wet for longer. Not as in soft while curing, but wet while drying between uses...

Interesting! I don't think I've had that experience.

 

[BattleGnome]

I HPd with a very conditioning high linoleic recipe and a little rose clay (I am colour coding my endeavours), while that's a pretty extreme % it is waaay more drying than I expected and also still has that wet feel.

Interesting on the wetness observation. I may eventually test the comparison.

I just wanted to note that the clay could also be causing the dryness. Have you tested other (more familiar) recipes with and without the clay to get a feel for how your skin interacts?

 

[Shelldybop]

Sodium Citrate is a salt that really likes water and can soften soap for that reason. ...(vinegar for hardening...

Yup, that seems to be the reason for staying wet. Please tell me more about vinegar for hardening?

I just wanted to note that the clay could also be causing the dryness.

Ya, Ive used clays before. Probably more due to there being 20% extra salt!

 

[SudsanSoaps]

I used citric acid at 2% because I have super hard water. Seemed liked it made my soap never get very hard so I add either vinegar or lactic acid also.

 

[bumbleklutz]

I've used both citric acid (reacted with extra NaOH to form sodium citrate) and Tetrasodium EDTA as chelating agents in bar soap to combat my extra hard water. For me, Tetrasodium EDTA wins hands down. Not only does it help to combat DOS in combination with ROE, but by binding up some of the hard water ions it really boosts lather and reduces scum more effectively than sodium citrate; at least for me.

 

[Nanditasr]

I used citric acid at 2% because I have super hard water. Seemed liked it made my soap never get very hard so I add either vinegar or lactic acid also.

I've done the same a couple of days ago! Waiting to see what happens.

 

[earlene]

Please tell me more about vinegar for hardening?

There are several threads here on the forum about using vinegar in soap. I'll link one or two I have saved, but if you use the search feature you can find more. Also within threads, there are often links to more information on the topic.

How to use vinegar to harden your soap

Oil & Vinegar - Sodium Acetate in Soap experiment

Testing vinegar/sodium acetate in soap - phase II

 

[Steve85569]

I now use reacted vinegar for half of my liquid in making soap. When I get a new bottle of vinegar I react it with lye using the formula in the first post that earlene posted. That takes the 5% acetic acid in the vinegar and creates a solution of water and sodium acetate that is at 4.8%. Using half gives me sodium acetate at 2.4% which more than compensates for the sodium citrate I use as the chelator.
Since the sodium acetate is a hardening salt ( as opposed to sodium citrate) it helps create crystaline structures within the soap matrix resulting in a harder, longer lasting bar of soap.

Now mind you that's working from my memory so I could be wrong on just how it works to make a harder bar. Someone with more knowledge of chemistry will correct me and set the facts in place for us if I am leading you astray.

 

[lsg]

I have to say thank you to those of you who recommeded EDTA for liquid soap. I tried it and am now using my glycerin liquid soap for hand washing dishes. Before adding the EDTA, I had a problem using liquid soap with our hard water. Any more recommendations willl be greatly appreciated.

 

[DeeAnna]

...soaps with CA stay wet for longer. Not as in soft while curing, but wet while drying between uses... I made a 20% citrate bar ... [it] still has that wet feel....

I just read the last several posts in this thread and I wanted to respond to this one.

When combined with NaOH, citric acid makes citrate. Citrate is a type of salt, as chemists define salts, and salts are often hygroscopic (chemicals that attract and hold water).

I get the impression you were expecting this soap to act like a normal soap -- one made with little or no added salts -- when it's actually closer to a salt or spa bar.

 

[bristles]

sorry to bump an older thread but when do you add the EDTA or sodium citrate when making soap? ill be making hot process soap and want to use this for the hard water where i live

 

[Dahila]

I add it to water just before lye, You asked about difference with EDTA and Sodium Citrate, I think my soaps with EDTA lather better. I still have some with Sodium Citrate.
BTW Disodium EDTA is much better for lotions cause is lower ph Disodium have ph of 5, So I switched for lotions to Disodium EDTA (Irishlass )

 

[john7]

sodium chloride and sodium phylate are cheaper, easier on the skin, and natural. They work pretty well as chelating agents.

 

[DeeAnna]

Sodium chloride (table salt) is not a chelator. Chelators must have multiple bonding points in their structure so they can properly immobilize multivalent metallic ions. The chloride ion (Cl-) has only a single bonding point and thus is not effective as a chelator.

Sodium phytate is indeed a useful chelator. I agree it is arguably more "natural" than tetrasodium EDTA, but it is not necessarily more "natural" than citrate. If we can make citrate from fresh-squeezed lemon juice (or other citrus juice) and a bit of NaOH, it's pretty "natural" as things like this go. Phytate is quite a bit more expensive, not cheaper, than EDTA or citrate based on the suppliers I checked.

 

[Paulie]

I use Sodium Gluconate.

 

[gloopygloop]

I use Sodium Gluconate.

Yes I do too.

 

[penelopejane]

Sodium gluconate is phenomenally expensive in Australia. So I use ctric acid which is AU$7 (US$4) a kilo (35oz).