Liquid Soap for Hard Water

[gabrielet]

Hello,


I live on a ranch in New Mexico and our water has about 7,000mg of calcium sulfate per liter. This causes real, non-detergent soap, like we make, to percipitate the sulfates out of the water leaving a film on dishes, sinks, etc.

Since we don't want to use Dawn or any other commercial soap that contains sodium lauryl sulfate, can someone share a recipe (if one exists) for a liquid soap that would act like a detergent and keep the sulfate film off the dishes?

Thank you for any help,

Gabriel

 

[lsg]

Try using terasodium EDTA in your liquid soap. Here is more info:


https://classicbells.com/soap/EDTA.asp#:~:text=It increases the shelf life,is used in hard water.

 

[Zany_in_CO]

Hi Gabriel!
You can use a 20% solution of citric acid if you prefer instead of EDTA.
Use Rate: 0.06%, warmed and added to the warm diluted soap. It tends to "flake out" when added. Just be sure to warm the batch to 140°F before hand and mix gently to incorporate. No problem. Sequester 2 weeks.

This causes real, non-detergent soap, like we make, to percipitate the sulfates out of the water leaving a film on dishes, sinks, etc. ... can someone share a recipe (if one exists) for a liquid soap that would act like a detergent and keep the sulfate film off the dishes?

If your LS leaves a film on dishes, sinks, etc. it may be due to the liquid soap paste to dilution water ratio you use. Generally speaking,
100% olive oil LS requires 15-20% soap to 85-80% dilution water.
On the other end of the spectrum,
100% coconut oil LS requires 40% soap to 60% dilution water.
All other combos fall somewhere in between. When the dilution forms a skin on top, that's an indication you're at the optimum amount of water needed. Add just enough water to incorporate the skin.

Adding a bit of Rosin to your formula may help.
ROSIN saponifies much like an oil but without any resulting glycerin. It gives a smooth cold cream finish to the lather and also acts as a detergent and preservative.
SoapCalc - Rosin has the same SAP value as Wheat Germ Oil.
May cause contact dermatitis in sensitive individuals.

If interested, please post your recipe, technique and process in the Recipe Feedback Forum and we can go from there.

 

[DeeAnna]

Speaking in a technical sense, soap is a detergent, meaning any surface active agent (surfactant) that can clean. It's just not the kind you want. There is no way to make soap act like a synthetic detergent.

I'm a little puzzled about your statement that it's the sulfate ion that's reacting with the soap. Soap reacts with positively charged calcium ions to create a precipitate of insoluble calcium soap -- soap scum in other words.

Unless I'm missing an important part of the chemistry involved here, I would expect the negatively charged sulfate ions to remain in solution or to react with positively charged sodium ions to form sodium sulfate which is soluble in water.

A chelator only removes positively charged ions -- the "hard water" ions such as calcium or magnesium or whatever -- in the water. It does not immobilize negatively charged ions, such as the sulfate you're talking about. You're going to have to look into a whole-house or point-of-use sulfate removal system if you specifically want to remove the sulfate.

A chelator has its limitations for hard water treatment. When you wash clothes in a washing machine, wash dishes in a sink full of water, or take a tub bath, there is a lot of water involved, and thus there are more hard water minerals to treat. You cannot realistically pack enough chelator into a soap so it can effectively treat that much hard water. A chelator like citrate or EDTA in your soap is effective at treating small amounts of hard water to reduce soap scum. An example would be the water that is in your washcloth when you shower or when you "spot wash" a dish with a soapy sponge.

More on the limitations of a chelator in soap -- Chelator limitations | Soapy Stuff

 

[Zany_in_CO]

Check out this post today on another forum:

https://www.soapmakingforum.com/threads/what-soapy-thing-have-you-done-today.42556/page-879#post-852629

ETA: Based on what @DeeAnna said above, perhaps adding a little water softener such as 20 Mule Team Borax or Liquid Calgon to your dilution water would increase it's effectiveness.

 

[gabrielet]

Perhaps I'm not doing this right, but I mixed a 50:1 soap to citric acid (50g+0.5g) and it created the precipitate shown in the photo.

 

[Zany_in_CO]

Perhaps I'm not doing this right, but I mixed a 50:1 soap to citric acid (50g+0.5g) and it created the precipitate shown in the photo.

It's best to dilute the citric acid before adding it to the soap. Read post #3 again.
That being said, try warming up what you have to 140°F or so, and stir, to see if that will dissolve the particulates.

 

[gabrielet]

Thanks for the response. I was hoping I could make it work by just mixing the citric acid without the extra water. But I suppose that little bit of extra water would be inconsequential to the total volume.

 

[DeeAnna]

Perhaps I'm not doing this right, but I mixed a 50:1 soap to citric acid (50g+0.5g) and it created the precipitate shown in the photo.

No, you're not doing it right. Did you do any research about using citric acid in soap? I've spent hours advising people on this forum about the proper use of citric acid in soap and I have an article on my website that summarizes the same advice. There is a second article on my website that explains the limitations of chelators in soap and also briefly explains why you can't just dump citric acid (or any other acid) into soap and still have soap afterwards.

You MUST add sufficient sodium or potassium hydroxide to neutralize the acid into citrate. If you don't add the alkali, the acid will react instead with the soap. The result of adding acid to soap is the soap decomposes, as you have learned. The decomposition cause fatty acids to precipitate.

Also you added a massive overdose of citric acid to the soap.

 

[gabrielet]

No, when I asked how to address the hard water precipitate, I had no information at all that citric acid was even an option, so I wouldn't have done any researd on it. This thread was what I was going with, by the information above that said, "You can use a 20% solution of citric acid if you prefer instead of EDTA.
Use Rate: 0.06%, warmed and added to the warm diluted soap. It tends to "flake out" when added. Just be sure to warm the batch to 140°F before hand and mix gently to incorporate. No problem. Sequester 2 weeks."

I will take a look at your article. Thanks.

 

[DeeAnna]

I see now why you did what you did. I thought you were testing an idea created out of thin air, and that's why I sounded cranky. I didn't re-read the whole thread to make the connection between your experiment and Zany's advice. I apologize for being testy with you.

I have no idea why Zany thinks this is sound advice. It doesn't make any chemistry sense to just add citric acid to liquid soap with the goal of forming the chelator citrate without also causing the soap to decompose, as you found out. That's what the "flakes" are -- fatty acids from the decomposition process.

She can explain why she thinks this is a valid method and help you troubleshoot the problems you're having.

 

[gabrielet]

Okay, I understand now. I don't mind an occasional "cranky" didact, if the information is worthy of the embarrassment — which it is. Thank you.

 

[Zany_in_CO]

I have no idea why Zany thinks this is sound advice. It doesn't make any chemistry sense to just add citric acid to liquid soap with the goal of forming the chelator citrate without also causing the soap to decompose, as you found out. That's what the "flakes" are -- fatty acids from the decomposition process.

I'm SO sorry I wasn't clear. The 20% citric acid is made ahead of time and dissolved in water (not the soap) and then added at a rate of 0.06% after dilution while the batch is still warm. SOURCE: Making Natural Liquid Soaps by Catherine Failor, pp. 39 & 42.

 

[gabrielet]

I don't think it was as much your fault, Zany, as it was that I didn't pay close attention to the numbers. After I re-read it a while ago, I realized what the 0.06% meant. Thank you for the link, too.

 

[DeeAnna]

The info in Failor's book is for neutralizing a lye heavy soap. The info Failor provides in that book is not about creating sufficient citrate in a not-lye-heavy soap to function as a chelator ... and also not ruining the soap in the process. These are two different situations that require different techniques.

 

[gabrielet]

I see. Then the info there is more about titrating for pH balance?

 

[DeeAnna]

Are you still talking about the topic of using citric acid to make a citrate chelator in your soap? If you are, this specific issue has nothing to do with lye heavy soap and the pH of said soap, so please let's not get lost in the weeds. If you want to discuss these topics, please start a new thread with those issues as the subject.

 

[gabrielet]

No, I was simply clarifying my take on what you wrote about the contents of the book by failor. There was nothing off-topic about it.

 

[Zany_in_CO]

Well, to be clear, "the topic of using citric acid to make a citrate chelator in your soap" is a whole 'nuther matter and deserves a separate thread. I understand what DeeAnna is referring to about getting "lost in the weeds", i.e., off-topic. The process of making a citrate chelator is more complex than simply adding a 20% solution of CA to finished liquid soap.