Lowering HP PH with Citric Add Solution

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Kcryss

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I came across an interesting blog about lowering the PH of HP Soap to make Shampoo Bars. It caught my attention so had to read it of course.

The though process is to add the Citric Acid solution at the end of the cook. One person said she excludes 90g of water during the lye prep and adds it back in after the cook in the form of water/beer/juices etc. based on the recipe she is using. That is when citric acid solution would also be added to decrease the PH for facial bars etc.

Any thoughts on this process? Sounds feasable to me and maybe worth a try on a small experimental batch. Would solve the problem of PH too high for Shampoo bars and provide a more liquid (pourable) soap for molding.

Here's the url if anyone is interested.
http://jenorasoaps.blogspot.com/2013/10/ph-in-handmade-soap-shampoo-bars-citric.html
 
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atiz

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I'm sure some more knowledgeable people will chime in, but I thought you cannot lower the pH of soap without it ceasing to be soap. I would worry that it would become a mush and/or separate. But this is just armchair thinking, so if anyone has tried it and it works, that would be great.
 

shunt2011

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Atiz is correct. You cannot lower the ph enough in regular soap. It will separate and no longer be soap.
 

Kcryss

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Well darn! That's very disappointing news. I thought I had stumbled upon the holy grail! lol
 

Kcryss

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Shame on her for advocating the use of ACV to bring the hair back to "normal" ... which is what using ACV as a rinse does.
 

IrishLass

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Wow! Definitely for shame! That soap will not have a pH of 7! It is chemically impossible for an alkaline salt of a fatty acid (which is what soap is by definition) to be neutral (which is what a pH of 7 is). Like Shunt said, if it did, it would no longer be soap, and would no longer be capable of cleaning. One thing that recipe will produce is a soap with a higher superfat....which the third person to comment under the recipe confirmed for me by saying that the soap leaves her hair very greasy at the scalp, worse than before using it.

I was reading further down in the comment section, and all I can say is that some of the advice given by various of the BB staff is just horrible and plain wrong. Some commentators began calling them out on the bad and misleading advice, but so far, I'm not seeing any evidence that any of the staff that are answering the questions has any understanding of the chemistry of soapmaking. Yikes! :eek:


IrishLass :)
 

Kcryss

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Ohh ... ok. Makes sense now. I understand what was meant by "no longer soap." Wasn't exactly sure what that meant. Thanks for the info and clarification.
 

Deb Walker

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I use a citrate and am happy to lower the pH. In the 7's (not 7 exactly) is an improvement from in the 8's.
 

Kcryss

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I use a citrate and am happy to lower the pH. In the 7's (not 7 exactly) is an improvement from in the 8's.
And citrate lowers the ph but doesn't lower it to the point of the soap ceasing to be soap?
 

DeeAnna

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Citrate is a salt, not an acid. It won't lower the pH to speak of when used in soap in the recommended amounts.

A mixture of citric acid and sodium citrate forms a slightly acidic buffer solution (pKa of 6.6) but that's not citrate + soap and you can't equate the behavior of the citric acid and citrate buffer with what you get by adding citrate to soap.

Soap has a normal pH ranging from 9 to 11 depending on the fatty acids present in the soap. It's possible the pH might be a bit higher or lower than that, but most soap tests between 9 and 11 if the test is done correctly.

Any soap that has a pH that is truly below 8.5 is no longer soap. It will be some mixture of soap and soap that has decomposed into fatty acids.

Most test strips are inaccurate and will usually tell a person that their soap tests lower in pH than what the real pH is. Even the best pH strips (Machery Nagel being my top pick) and high quality pH meters will be just as inaccurate and give you unrealistically low readings if you don't prepare the sample properly.
 

Kcryss

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Citrate is a salt, not an acid. It won't lower the pH to speak of when used in soap in the recommended amounts.

A mixture of citric acid and sodium citrate forms a slightly acidic buffer solution (pKa of 6.6) but that's not citrate + soap and you can't equate the behavior of the citric acid and citrate buffer with what you get by adding citrate to soap.

Soap has a normal pH ranging from 9 to 11 depending on the fatty acids present in the soap. It's possible the pH might be a bit higher or lower than that, but most soap tests between 9 and 11 if the test is done correctly.

Any soap that has a pH that is truly below 8.5 is no longer soap. It will be some mixture of soap and soap that has decomposed into fatty acids.

Most test strips are inaccurate and will usually tell a person that their soap tests lower in pH than what the real pH is. Even the best pH strips (Machery Nagel being my top pick) and high quality pH meters will be just as inaccurate and give you unrealistically low readings if you don't prepare the sample properly.
Thank you DeeAnna! I'm buying a digital PH tester and will throw away my strips. :)

Also, thank you for the 8.5 indicator. I'll use my new tester to make sure it's 8.5 or above.

One last note, I have been reading a great deal about PH and have come to realize that it isn't the end all be all I thought it was in terms of identifying a non irritating/harsh product. It seems the more I learn, the more I realize how much more I need to learn. :)

Thank you all for your patience as I learn and question. :)
 

DeeAnna

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I've shown this info before, but it seems appropriate to share it again. The commercial soaps and cleansers in the table below were tested for pH and for their ability to irritate the skin. The higher the irritation index, the more irritating.

The authors defined cleansers with index values of about 1 as appropriate for sensitive skin that is easily irritated.

Looking at the general population, not just people with sensitive skin, the authors stated the various types of Zest soap is preferred by about 42% of the general population. Palmolive soaps are second at about 18% followed by Dove cleansers at about 11%.

The popularity of these cleansers suggests the average person's skin can do fine with cleansers with irritation indexes in the mid-3 to low-5 range.

Looking at mainly the soaps, you can see that some of the highest pH soaps tested quite low on the irritation index (Johnson's Baby Oat, Johnson's Baby, and Lux). Many soap makers who believe low pH is the Holy Grail of mildness should think about that fact.

While it is true that higher pH can contribute to a cleanser's ability to irritate the skin, whether it's a soap or a non soap cleanser, it's not a surefire absolute correlation. Obviously other factors besides pH also contribute to the ability of soap to irritate the skin or not.

BarandaL Cleanser irritation vs pH.jpg

Here are just the soaps from the previous table. They have been sorted by pH. I said earlier that the typical pH of soap runs between 9 and 11. You can see most of the soaps tested in this study fall within that pH range I mentioned with several that are even higher. None of the soaps had a pH below 9.5.

Baranda soap irritation vs pH.jpg
 
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Kcryss

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Really great info DeeAnna! That very much coincides with what I've been finding in the last day or so regarding PH. It seems that it's almost as much a marketing gimmick as anything else really.

As someone with very dry skin, living in a semi arid climate, I've used Dove for many years until about 6 months ago when I switched to natural soap. I don't find it to be any better or worse for dryness then Dove and in fact is a lot nicer.

I'm actually surprised to see Zest etc. not showing any higher on the irritation index. They have always been very drying on my skin.

Again, great info! Thank you so much for posting.
 

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