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What's the deal with solid shampoo

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Emmanuel

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Hello evryone !

I'm very sensitive on the scalp and before, industrial shampoo was irritating for it. So I tried solid shampoo and it was much better. And then I tried solid soap. Now I shampoo with a solid CP soap with good lather and it's perfect , I have 0 problem with it. So why is solid shampoo so different in terms of composition of solid soap ? I guess it's probably linked to the pH.

Have a nice day
 

Primrose

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Hi Emmanuel! If you search the forum for "shampoo bars" you will probably find more threads than you want regarding this topic haha basically in a nutshell, if someone is making/selling shampoo bars it is one of two things..it could be a standard lye based soap, some people choose particular oils and additives that are supposed to be better for the hair. Or it could be a syndet (synthetic detergent) bar. Basically the thing with lye based soap is that due to the pH it doesn't suit everyone to use as shampoo. In fact it appears that people who can use lye based soap as shampoo without causing hair damage, seem to be the minority. Most people require a syndet bar in order to keep their hair healthy. and the solid bars are on trend these days because of reduced plastic packaging.
 

Emmanuel

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Hi Emmanuel! If you search the forum for "shampoo bars" you will probably find more threads than you want regarding this topic haha basically in a nutshell, if someone is making/selling shampoo bars it is one of two things..it could be a standard lye based soap, some people choose particular oils and additives that are supposed to be better for the hair. Or it could be a syndet (synthetic detergent) bar. Basically the thing with lye based soap is that due to the pH it doesn't suit everyone to use as shampoo. In fact it appears that people who can use lye based soap as shampoo without causing hair damage, seem to be the minority. Most people require a syndet bar in order to keep their hair healthy. and the solid bars are on trend these days because of reduced plastic packaging.
Wow thank you for the answer !
Turns out I just got lucky ^^
My goal would be to neutralize the pH with citric acid in powder dispersed into the soap paste but I need to try it out extensively to see if this work ^^
 

shunt2011

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Wow thank you for the answer !
Turns out I just got lucky ^^
My goal would be to neutralize the pH with citric acid in powder dispersed into the soap paste but I need to try it out extensively to see if this work ^^
The answer to your solution is a big no. You can't lower the PH enough to make it suitable. There are several threads on this as well here. If you try to lower the ph too much it will no longer be soap, it will break down.
 

Emmanuel

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The answer to your solution is a big no. You can't lower the PH enough to make it suitable. There are several threads on this as well here. If you try to lower the ph too much it will no longer be soap, it will break down.
I totally agree , if your solution is no longer alkaline it won't make a soap. But I was wondering if it was possible to integrate powder into the solid and well saponified soap so that the lather resulting from it will be overall neutral :). Like for example if you melted a melt and pour soap then add citric acid to it , so that it won't disolve nor attack the soap , you would have a soap with integrated citric acid grains that will acidify the resulting lather. Does this breaks down the soap too ?
 

SoapySuds

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@Emmanuel

I just tried this with two bars.

I weighed out grated cp soap into a 10% solution and fully dissolved it to find the ph of my bar. I then weighed and added citric acid to my solution until I reached a ph of 5. I notated the weight of citric acid to make the bar the desired ph.

I then finely grated my soap and weighed it out for a single bar, but got one and a half for my mould (I didn’t measure my mould just eyeballed it) added dry citric acid amount needed to make the bar ph suitable for shampoo and a small amount of scent oil at 1% weight. I then added a small amount of water to get my bar to stick together and then poured it into my mould.

Now that my bar is dry enough to release from the mould and use, here’s what I have noticed on using it:

It’s soft and squishy, and not in a good way. It also does not lather like I want it to. I have to work to get this thing to lather and once it hits my hair, the lather is gone. I’ve slid the bar around on my head and still no distinguishable lather. Does my hair get clean? Doubtful, I’ve washed it several times and I have a greasy feel to my hair afterwards.

I will probably try one more time, but I’m doubtful.

The chemistry goes like this:

If you have two salts (citric acid and sodium tallowate) that are dry, they will typically not react with each other. They need to be in a solution to react. That’s where the tricky part comes in. Because a small amount of solution is needed to bind all the dry ingredients together, and then have that small amount dry up.

Each time the bar is used, it’s going to make a solution on the outside and absorb water to some of the interior, all the while making a solution with two ingredients that will cause each other to break down.

It’s basically fighting a losing battle.

I am right there with you in wanting to make a shampoo bar from CP soap, and I have been on this journey and I identify with your thought process.

Been there done that, but meh, try it yourself :)
 

Emmanuel

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@Emmanuel

I just tried this with two bars.

I weighed out grated cp soap into a 10% solution and fully dissolved it to find the ph of my bar. I then weighed and added citric acid to my solution until I reached a ph of 5. I notated the weight of citric acid to make the bar the desired ph.

I then finely grated my soap and weighed it out for a single bar, but got one and a half for my mould (I didn’t measure my mould just eyeballed it) added dry citric acid amount needed to make the bar ph suitable for shampoo and a small amount of scent oil at 1% weight. I then added a small amount of water to get my bar to stick together and then poured it into my mould.

Now that my bar is dry enough to release from the mould and use, here’s what I have noticed on using it:

It’s soft and squishy, and not in a good way. It also does not lather like I want it to. I have to work to get this thing to lather and once it hits my hair, the lather is gone. I’ve slid the bar around on my head and still no distinguishable lather. Does my hair get clean? Doubtful, I’ve washed it several times and I have a greasy feel to my hair afterwards.

I will probably try one more time, but I’m doubtful.

The chemistry goes like this:

If you have two salts (citric acid and sodium tallowate) that are dry, they will typically not react with each other. They need to be in a solution to react. That’s where the tricky part comes in. Because a small amount of solution is needed to bind all the dry ingredients together, and then have that small amount dry up.

Each time the bar is used, it’s going to make a solution on the outside and absorb water to some of the interior, all the while making a solution with two ingredients that will cause each other to break down.

It’s basically fighting a losing battle.

I am right there with you in wanting to make a shampoo bar from CP soap, and I have been on this journey and I identify with your thought process.

Been there done that, but meh, try it yourself :)
Thank you for your experience :)
 

SoapySuds

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On the other hand, I have no problem making a liquid shampoo with a ph of 5.5.

Liquid shampoo doesn’t travel well though.
 

DeeAnna

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The word shampoo is a generic term for any product you use to wash your hair. It doesn't define anything more than that.

A particular product used to wash hair can be a lye-based soap or it can be a synthetic detergent.

Whether the "shampoo" is a liquid or a solid doesn't define what kind of cleanser it is. I can make a liquid soap that could be used to wash hair. I can also make a syndet liquid cleanser that could also be used to wash hair.

In this thread, I think it's going to be really important to say clearly what kind of shampoo a person is talking about. If you talk about soap-as-shampoo but don't define that clearly, your reader could easily assume you are talking about syndet-as-shampoo.

***

When enough citric acid is added to soap to reduce the pH to about 5, the mixture is going to be 100% fatty acids and citrate. No actual soap.

It doesn't surprise me that this product is soft and doesn't lather well and your hair feels greasy after using it.

Study up on how "buffers" work and learn more about pKa and what the pKa is for fatty acid and soap mixtures. This chemistry knowledge will help you to understand why you cannot have a functional soap below a pH of about 9.
 

SoapySuds

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But I have liquid soap, made with KOH, adjusted to 5.5 ph.

I don’t know why it works with KOH, maybe it’s how I’m treating it that prevents it from separating.

I know that yes, the chemistry is there for it to separate.

But I currently have made liquid shampoo, no syndet, Potassium hydroxide paste base that I adjust after sequestering it. I use my paste, citric acid, water, some scented oil, and a gum. I’m not at home currently, so I can’t tell you which gum, but I do have a formula that does not separate, gets good foam and doesn’t strip my hair.

I don’t make up more than a six month supply at a time, and if I don’t do the steps I have lined out, it separates and becomes oil and water.

Yes. It is possible to make soap based liquid shampoo with a low ph. I know, I’ve done it. I use it, my husband uses it.

Bah. It’s cool. Come over I’ll show you how I make it.
 

Kcryss

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But I have liquid soap, made with KOH, adjusted to 5.5 ph.

I don’t know why it works with KOH, maybe it’s how I’m treating it that prevents it from separating.

I know that yes, the chemistry is there for it to separate.

But I currently have made liquid shampoo, no syndet, Potassium hydroxide paste base that I adjust after sequestering it. I use my paste, citric acid, water, some scented oil, and a gum. I’m not at home currently, so I can’t tell you which gum, but I do have a formula that does not separate, gets good foam and doesn’t strip my hair.

I don’t make up more than a six month supply at a time, and if I don’t do the steps I have lined out, it separates and becomes oil and water.

Yes. It is possible to make soap based liquid shampoo with a low ph. I know, I’ve done it. I use it, my husband uses it.

Bah. It’s cool. Come over I’ll show you how I make it.
I would love to learn how you make it! :) Can I come over? I'm in Colorado so might take a bit to get there.
 

DeeAnna

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"...Yes. It is possible to make soap based liquid shampoo with a low ph. I know, I’ve done it. I use it, my husband uses it...."

Liquid soap made with KOH, just like bar soap made with NaOH, must be alkaline to be soap. Measuring pH with test strips is really inaccurate on soap and the way most soap makers use the strips adds even more inaccuracy. The strips indicate the pH is much lower than it really is.

But if you truly believe I am sadly mistaken, then you need to discuss your soap with Kevin Dunn, the author of Scientific Soapmaking. He's been looking for someone who makes lye-based functional soap that has a verified pH of 8 or less. No one has yet won the prize. Your soap would solve his long-standing quest, and he really should know about it.
 

SoapySuds

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Ok. I mean I could be mistaken.

I’m willing to admit I may be making an error somewhere.

It is in my plan to obtain a ph testing electronic device. I believe I am storing my strip paper correctly, and I am able to distinguish between the shades well.

But ok.

I have read similar accounts of being able to change ph, but again I could be mistaken. And I’d love to share.

There are steps I cannot do with NaOH that I can with KOH. It’s hard to explain, it’s something that needs to be observed... and for the greater good of the forum and so it will make everyone happy. I acquiesce my position.

My official stance: it can’t be done. It separates and makes a mess. There is no such thing as soap with a low ph.

I’d like to chat with Dunn, if he’s open to it.
 

Carla Burke

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Emmanuel, the easiest answer to using a lye vs syndet bar is with the lye, rinse after washing, using an acid/ water solution. Most people use apple cider vinegar, and believe the scent goes away, after it dries. My husband hates that scent, and swears it doesn't go away, so I rinse with a lemon juice/ water solution. It works just as well, he likes it, and frankly, so do I.
 

DeeAnna

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Storing and reading pH test strips correctly is important, but it's the inaccuracy inherent in the actual strips that I'm talking about. Also the method used to test the pH is also important for accurate results. Most soap makers don't test correctly. They test the pH of a concentrated soap solution and it's not accurate to do that.

"...My official stance: it can’t be done...."

I'm not asking you to parrot some official party line ... because there is none and I'm not interested in blind obedience. I'm interested in encouraging you to learn more about the chemistry so you can really understand what you're doing, rather than assume or guess.

If you want to push the envelope of what lye-based soap can do, then at the very least, buy a copy of Dunn's Scientific Soapmaking and read chapter 13, and very specifically section 13.2. That will give you a basic but accurate overview of the chemical changes that happen when you add acids to any lye-based soap.

"...I’d like to chat with Dunn, if he’s open to it...."

He's a nice guy. I encourage you to contact him.
 
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