Does water really matter?

[The Efficacious Gentleman]

Very cool experiments.

Can I ask a huge favour - could you make up some sodium citrate next time you have the soap making kit out? I'd love to see that next to the EDTA for comparision

 

[DeeAnna]

Gent -- So many people are using sodium citrate in their soaps lately, so I agree would be a good thing to compare it with EDTA, which I suspect is used a lot less than the citrate.

 

[zolveria]

Water and soap

I do not bother with water antics. My grandmother was a farmer wife.
She did not bother to distill water etc. SMH. SOAP IS SOAP to me anyways. Salt water soap. Coconut water soap. Milk soap. Apple juice. IT IS OR WAS what ever the farmer had at hand. My soap are Always Loved by everyone. Distilled water to me use if making Glycerin soap my lotions and Serums.
just my opinion

Have a Blessed Day

 

[Dorymae]

I do not bother with water antics. My grandmother was a farmer wife.
She did not bother to distill water etc. SMH. SOAP IS SOAP to me anyways. Salt water soap. Coconut water soap. Milk soap. Apple juice. IT IS OR WAS what ever the farmer had at hand. My soap are Always Loved by everyone. Distilled water to me use if making Glycerin soap my lotions and Serums.
just my opinion

Have a Blessed Day

Normally I agree, however this is showing the clarity you can achieve with distilled water. If you don't care how clear or milky your liquid soap is then this would not pertain to you.

 

[zolveria]

Yes Very True

Normally I agree, however this is showing the clarity you can achieve with distilled water. If you don't care how clear or milky your liquid soap is then this would not pertain to you.

Yes very True . If you are coloring them. I guess it really does not Matter

 

[ngian]

Well I tried to do similar experiment with what DeeAnna did but using Sodium Citrate.

I'm not a chemist expert and just did what I thought it would be logical.

I have used two soap bars of the same recipe, but the second one was with 3% of sodium citrate on its lye water.

I cut about 1gr of each soap bar and diluted them in 4 jars that had 200gr of water each.

Looking at the next pic the two topmost jars had my hard tap water, and the two lowest deionized water, while the right jars had the soap bar with sodium citrate in its recipe diluted while the left jars the one without.

As I can see and understand, sodium citrate on a CP recipe doesn't affect at all how it will react with the specific amount of water. What I did next is to incorporate sodium citrate inside the right jars to see how it would affect the water.

The first one is showing the original dilution, the second when I added 5ml SC and the third one when I added 10ml more of SC.

It seems that as I was adding SC, the water was getting a little bit more clear, and few bubbles could stay alive for a while.

When I tested the two bars by washing my hand with my hard water, they both were lathering the same way showing many bubbles at the same time. The only difference I could see is that the bar with sodium citrate in its recipe had an average of bigger bubbles, as if someone was pumping them with air, while the soap without SC was making the same amount of bubbles but smaller in size.

I don't know if I did a "right" experiment or someone can make any conclusions upon using SC, so anyone can conduct me in doing another experiment.

So in contrary with EDTA, I feel that it needs more SC to get a similar effect of EDTA, but arises another question:

Assume that we use 4sodium EDTA or SC in our recipe of liquid or soap bar, can it work as a chelator and defeat all the hard water's minerals that are running plenty through our tap or EDTA is moslty used as a preservative, and SC as a "PH lowering agent"?

 

[DeeAnna]

One of the issues I didn't think about when you and I were discussing your plans by PM is this -- A chelator like sodium citrate or EDTA added to soap usually does not have to treat ALL of the water. It only has to chelate the hard water minerals in the water right where the soap is.

So dissolving a gram of soap in 100-200 g of water might not be a realistic scenario for how a chelator works to prevent soap scum when using bar soap in the shower. The dose of sodium citrate from the soap itself in your experimental soap-water solution would be tiny -- 0.03 g SC per 200 g water or 0.015%. You ended up adding quite a bit more SC to get some clearing in your soap and hard-water mixture. In my tests with EDTA in a soap-water solution, my dose of EDTA also ended up being quite large to get effective clearing of the solution -- 0.2 to 0.47 g EDTA per 100 g water.

In either case, that's far more chelator than is realistic to pack into each gram of soap. I think the results of your tests and mine show that EDTA and SC really can help to reduce soap scum formation, but they aren't magical problem solvers. They can't totally eliminate scum, especially in the situations where a small amount of soap is added to a large amount of water -- for example washing dishes in a basin of soapy water or washing clothes.

But I think most of us tend to use soap in a more concentrated form -- soap rubbed directly onto hands, skin, or cloth to wash the body or soap squirted onto a scrub pad to wash dishes -- and in these kinds of situations, I think a chelator can be quite effective. All it has to do is chelate the minerals in a small amount of water long enough for the soap to do its job and be rinsed away. If one's soap is very hard (as yours is), a chelator won't be as effective in preventing soap scum formation, but it might still be effective enough to be worth using.

As you noted with your hand washing tests, there is some slight difference between soap lather with no chelator vs. soap lather that contains chelator. Another empirical test would be to shower with the two soaps and evaluate the differences in your skin -- does the skin washed with chelated soap feel smoother / less sticky than the skin washed with plain soap? That would be helpful observation to tell you whether the chelator is providing some benefit.

A lot of the soap testing that's done by commercial soap makers is also empirical and somewhat subjective -- they are forever tweaking their recipes to get the best overall performance of their soap in the various water supplies their many consumers use. That's probably why some soap brands are regional rather than national or world wide.

 

[LBussy]

Yes very True . If you are coloring them. I guess it really does not Matter

I use non-colored shaving soap and the soap scum does matter. It's just plain nasty to see the layer of "mung" on top of the water, let alone what it does to the sink. I use syndet to clean my sink after I get done with my soap. That's just silly to have a very nice hand crafted soap and have to use a syndet afterwards. If I can get rid of the scum I want to.

Just because your grandmother made do with bacon drippings and wood ashes and whatever water was closest to her doesn't mean it was a soap that compares with contemporary soaps. To ignore science and say "this is how we've always done it" (insert amusing anecdote/story here) is just a little silly - especially if your soaps are for sale to others.

I love history and pay homage to those who came before us. I'm just betting however if your (or anyone's) grandmother had access to this information they would have used it. They did it that way because they had no choice.

Home softeners typically replace the hard water minerals with sodium from table salt (sodium chloride, NaCl), but it is difficult to remove all of the undesirable minerals with any water softening system.

When you describe water softeners like that it sounds like you could get the same results by adding just plain salt. I know you know that's not the case but I thought I'd add to this so people understand a little more of the chemistry (and swing it back around to a common reference).

The main tank has little plastic beads, called resin. The beads have a negative charge and attract the metallic ions because they have a positive charge. The tank is flushed with brine (either potassium or sodium chloride in water) and the weakly positively charged sodium ions are attracted to the resin where they sit and wait. That salt water is drained out and the tank is now ready to treat your water.

The tap/well/whatever water flows in and the beads provide a lot of surface area for the water. The Magnesium and Calcium ions are stronger and better looking to the resen (have a stronger positive charge compared to the Sodium or Potassium). The resin, harlot that it is, pulls in the Mg+ or Ca+ to the negatively charged surface of the resin and quite rudely knocks the Na+ ion off into space. The Chloride Anion (Cl-) who used to be with the Mg+ or Ca+ is left without a date. The Na+ and K+ ions are likewise heartbroken. So, the ions and anions get together and have rebound sex. This leaves a very tiny amount of potassium or sodium salt in the water - a 1:1 replacement of the Magnesium or Calcium salts. The water is not more salty, it's just different salt.

This is called ion exchange, and is exactly the same process that goes on in soap which makes soap scum - except instead of resin the metals strip the fatty acid of it's Sodium or Potassium and takes it's place on the soap salt molecule.

Chemistry is fun!