PH reduction

[kchaystack]

thank you for your notice but how could a soap have high ph and still doesn't wash all the skin oils and moisture? I'm asking to know more, any comprehensive online source you suggest about the factors you said?

The book Scientific Soapmaking by Dr. Kevin Dunn. His website is http://cavemanchemistry.com/scisoap/

But you have not given us any sources for your info so we have no way to refute your claims.

 

[Susie]

The oils you make the soap out of and the superfat you use has more to do with whether your skin gets stripped of oils or not.

 

[Dahila]

I ve read on swiftcraftymonkey and on other forum/blogs that soap bars arent good for hair and face because of their pH..

I ve tried them on my hair and on face of course and i havent any problem so far. But when i read all these things i stoped using them so often as before...

For hair not but face is a different story. Our body will do everything to keep it in balance and from 10-15 minutes skin ph goes back to the one it suppose to be , Healthy blood ph is 7.4 plus minus. I wash my face with soap occasionally activated charcoal soap, and have no problems. For hair I make a shampoo bar using very mild surfacants, (Susan's blog)

 

[The Efficacious Gentleman]

There is more than enough on this forum alone about pH and irritation not being linked - some of the mildest commercial soaps have pH levels higher than 10 and one even had 12. Some of those classed as most irritating were lower in pH.

Low pH does not automatically equate to a milder soap. Higher pH also does not automatically equate to a milder soap. A pH does not in itself tell us if a soap is safe to use or not. Which is why I said that for what we do, pH is really taking you down a wrong path

 

[Susie]

There is more than enough on this forum alone about pH and irritation not being linked - some of the mildest commercial soaps have pH levels higher than 10 and one even had 12. Some of those classed as most irritating were lower in pH.

Low pH does not automatically equate to a milder soap. Higher pH also does not automatically equate to a milder soap. A pH does not in itself tell us if a soap is safe to use or not. Which is why I said that for what we do, pH is really taking you down a wrong path

^^^^This!

Soap, however, is not for everyone's hair. Soap will damage some people's hair. Skin is a different story.

 

[DeeAnna]

...how could a soap have high ph and still doesn't wash all the skin oils and moisture?...

I get the impression that you are thinking pH is only thing that affects the cleansing ability of a soap. The fatty acids used to make a soap are far more important to the properties of the soap than its pH, assuming the soap is properly made so it does not contain free alkalinity (excess lye).

For example, a mostly oleic soap (olive oil) will have a higher pH than a mostly lauric-myristic soap (coconut oil). The coconut oil soap will be much harsher to the skin than the olive oil soap, however -- it will remove too much of the natural oils and proteins on the surface of the skin, leaving the skin feeling dry and perhaps irritated. One would expect the opposite result based on pH alone, so why is this the case? You have to look at the fatty acids in the soap, not the pH.

http://www.soapmakingforum.com/showthread.php?t=50018
http://www.soapmakingforum.com/showthread.php?p=510429
http://www.soapmakingforum.com/showthread.php?t=48845

 

[hlecter]

There is more than enough on this forum alone about pH and irritation not being linked - some of the mildest commercial soaps have pH levels higher than 10 and one even had 12. Some of those classed as most irritating were lower in pH.

Low pH does not automatically equate to a milder soap. Higher pH also does not automatically equate to a milder soap. A pH does not in itself tell us if a soap is safe to use or not. Which is why I said that for what we do, pH is really taking you down a wrong path

So could we say that the theory of some skin products and their pH has to be 5.5 is mostly a marketing? But for hair care products its somehow important...

 

[The Efficacious Gentleman]

I would think that not grouping skin care and hair care together in general is a no brainer as skin is not hair and hair is not skin. How one cares for a cat is different to how one cares for a dog, even though both are four legged animals.

As the topic is skin care, we'll stick to that. If the acid mantle is 5.5 and all that, then even water creates a disruption to it. People used non pH 5.5 products for ages and had great skin. It is marketing, as 10 minutes on this forum will tell you

 

[DeeAnna]

Skin can balance and repair itself. Hair cannot. IMO that's the biggest difference in a nutshell. There is at least one research study that shows the skin pH is altered even by washing with water, but it recovers quickly. As long as someone doesn't wash obsessively, using soap on the skin is not an issue.

The first image is a chart of the skin irritancy of commercial soap and non-soap cleansers vs. their pH. Athough there is a trend of irritancy going up as pH goes up, it's not a 100% correlation -- some of the least irritating cleansers have the highest pH (ex: Johnson's baby). The second image is the same information from the same source, but for the soap products only -- a little easier to digest if you only want to consider soaps by themselves.

I want to point out the pH of the commercial soaps ranges from 9.8 to 12.4. It annoys me when people assume, magically, that handcrafted soap is greatly different and somehow the pH should be greatly lower. It's lye-based soap ... it's going to have an alkaline pH.

 

[Susie]

Let's also remember that the outer layer of the epidermis is made of 10-25 (or more) layers of dead skin cells that are constantly sloughing off. They are there to protect the body from anything getting in. You really have to scrub hard to get down even to 5 or so layers. This means that all you are washing is dead cells anyway. It is not going to be adversely affected by a pH within the range of normal hand made soap long term.

What affects my skin the most is the superfat and the oils I use. I have dry skin already, with very little oil production even in my T zone on my face. I do not need any soap to strip more of those precious oils off of my skin. That means lower coconut oil, and superfat 5-8% always. Your skin may need different treatment.

 

[topofmurrayhill]

I know that high-pH soap stings the eyes more than lower-pH syndet. That's the whole point of "no more tears" advertising and is one of the established advantages of syndets. Beyond that, I don't personally experience significant issues with soap. Someone else might.

Deeana posts data from a research study and states that the correlation between pH and irritation isn't 100%. It would be remarkable if it was. All we need is for the correlation to be significant. The SAME study that data comes from reaches the following conclusions:

A significant correlation between pH and the [Irritation Index] of cleansers was found (P < 0.006). Most products recommended for sensitive skin have a considerable irritation effect, which is related to the pH of the product. Better regulation of advertisement specifications including the pH level and type of cleanser contained is necessary for the majority of soaps and cleansers.

P < 0.006 means that statistically it's extremely unlikely to be a coincidence.

I don't think we need to bend over backwards to say that syndets don't have a lower irritation potential because of their lower pH. They actually do, and rebuking someone for their interest in the pH of cleansers is not really appropriate in place of a reasoned response. It is ALSO true that concentrating a lot on the pH of artisanal soap isn't too useful. It is what it is, and there are limited things you can do about it.

I like making soap and I like using it. If that describes you too, then pH probably isn't a big issue for you. If you prefer how lower-pH products work for you, then syndets might be a better option. We have experienced soapmakers here who like them.

 

[AustinStraight]

Can't the acid mantle be washed off by non-alkaline cleansers, too? If it's basically just a layer of lipids + some other things, wouldn't you think any surfactant, CP soap or otherwise, would be able to remove it?

 

[topofmurrayhill]

Can't the acid mantle be washed off by non-alkaline cleansers, too? If it's basically just a layer of lipids + some other things, wouldn't you think any surfactant, CP soap or otherwise, would be able to remove it?

The "acid mantle" is a bit of a buzzword term. Reality turns out to be more complicated. Lipids do get washed away to one extent or another by any surfactant, but they don't have a pH. Acidity or alkalinity is a property of the water-based solution that permeates the skin.

The pH of a cleanser applied to the skin has a significant effect on that. There is a short-term effect (a few hours) that has been postulated to be the ONLY effect. However, there turns out to be a longer-term effect as well. Ultimately, there is a strong correlation between pH and the potential for irritation, due at least partially to the corrosive effect of high pH on proteins.

There seems to be a particular benefit for some people to using a slightly acidic cleanser, and it seems to be fine for people in general. Slightly acidic is better than neutral is better than alkaline. The most interesting paper I have on this comes from behind one of those nasty paywalls so I can't really share it.

These considerations usually come down to soap versus syndets. However, despite the fact that it gets dismissed out of hand here, you CAN make soap less alkaline and more mild. It's debatable how practical this is, but the principle is straightforward. The soap needs to be superfatted with fatty acids instead of oil. That means either making the soap with fatty acids instead of oil and using a lye discount, or you can fully saponify the oils and acidify the soap to separate some of the fatty acids.

I would guess that IrishLass' Cocoa/Shea LS superfatted with stearic acid is pretty gentle.

 

[The Efficacious Gentleman]

...... I don't think we need to bend over backwards to say that syndets don't have a lower irritation potential because of their lower pH. They actually do, and rebuking someone for their interest in the pH of cleansers is not really appropriate in place of a reasoned response. It is ALSO true that concentrating a lot on the pH of artisanal soap isn't too useful........

As the thread is about lowering the pH of a lye based soap because "low pH is best" I think that it is right to point out that pH is a false lead - the interest is not in cleansers as such, but lye-based soap.

While the study found a correlation between cleanser irritation and pH, the lye based soaps show no such correlation. As the aim is to have low irritation and it was assumed that pH was the key, it's important to keep those two points clear that low pH does not mean it's better for the skin than a higher pH. Maybe with syndets, but not when we include real soaps.

 

[ngian]

These considerations usually come down to soap versus syndets. However, despite the fact that it gets dismissed out of hand here, you CAN make soap less alkaline and more mild. It's debatable how practical this is, but the principle is straightforward. The soap needs to be superfatted with fatty acids instead of oil. That means either making the soap with fatty acids instead of oil and using a lye discount, or you can fully saponify the oils and acidify the soap to separate some of the fatty acids.

Is this because free fatty acids lowers the pH in an aqueous solution while mono-di- triglycerides doesn't affect the pH at all?

Or this is about the fatty acid / soap equilibrium (pH and PKa values of each fatty acid)?

 

[DeeAnna]

As the thread is about lowering the pH of a lye based soap because "low pH is best" I think that it is right to point out that pH is a false lead - the interest is not in cleansers as such, but lye-based soap....

This is precisely the point I was trying to make. Thanks, Gent.

 

[topofmurrayhill]

As the thread is about lowering the pH of a lye based soap because "low pH is best" I think that it is right to point out that pH is a false lead - the interest is not in cleansers as such, but lye-based soap.

The relationship between solution pH and clinical irritancy
for carboxylic acid-based personal washing products
RICHARD I. MURAHATA and MICHAEL P. ARONSON,
Unilever Research U.S
1994

Synopsis

The influence of formulation pH on the irritation potential of slurries formed from two commercial products composed entirely or partially of aliphatic carboxylic acid-based surfactants (fatty acids and their salts) was determined in vivo by use of a flex wash. Increasing the pH of a synthetic detergent/fatty acid slurry from its neutral value to a pH of 10 reduced its mildness. The neutral pH of the predominantly non-soap-based cleanser, therefore, makes a significant contribution to its mildness. If it were formulated at pH 10, it would be significantly harsher to the skin than the current neutral formulation.

The pH also had a significant effect on the irritation potential of soap-based cleansers. Decreasing the pH of soap slurries from their "normal" pH of approximately 10 to pH 7 reduced their irritation potential. The difference in alkalinity, as measured by pH, is directly related to the lower irritation potential of both of these formulations. These results demonstrate that pH has an important role in determining the differences in irritation potential of these complex skin cleansing compositions through effects on ionizable constituents.

 

[topofmurrayhill]

Is this because free fatty acids lowers the pH in an aqueous solution while mono-di- triglycerides doesn't affect the pH at all?

Or this is about the fatty acid / soap equilibrium (pH and PKa values of each fatty acid)?

It's about pKa and other factors that affect the proportion of soap to fatty acid. In the case of soap, it's chemistry and it's pH are related. The effect on the skin may relate intrinsically to the pH to some extent and also (according to the paper I quoted for The Gent) the formation of soap-fatty acid complexes that are milder for the skin than soap.

So the question of the pH of a liquid soap is probably relevant when you are comparing let's say IL's basic recipe with her cocoa/shea/stearic recipe.

 

[The Efficacious Gentleman]

I would be interested to see how the pH was changed in these cases - if we are comparing a 100% co soap at its standard pH against the same soap but with the pH altered, we would need to account for the changed 'recipe' of the soap.

Again, in what we do we do not work in theory, but practice. Lowering the pH of a liquid soap to 7 or 5.5 is not something an average soaper can look to do, especially not if they don't want to look at syndet/hybrid recipes.

Which means more consideration should be given to formulating a good recipe that works for someone and thinking about a recipe in those terms rather than measuring the pH of a soap and looking to reduce it to improve it

 

[topofmurrayhill]

Nobody is telling anyone what to be interested in when it comes to soap making, but pH is not uninteresting or irrelevant. While pragmatically it might not come up for most people, I would dismiss a new person's curiosity about it more thoughtfully.

If you happen to have hydrochloric acid lying around, you can lower the pH and make a little table salt in the process. I think the researchers did it that way. You can can use other acids or you can superfat with fatty acids in cases other than cold process soap.