Also consider "scientific soap making" - a very good book by Dr Kevin Dunn
Evaluating soap efficacy?
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Thanks Gent, that is probably the key to unboggling my mind. I like the analogies for soaping, it is when I try to explore the chemistry of it all, it seems like most articles assume a certain level of understanding to begin with, and searching around for those missing links just is not bringing up the info I don't understand - instead I get catapulted into scientific articles way above my head when I am really searching for the basics.
As for getting positive/negative charges wrong, that is just what my brain does to me. And with certain fatty acids stripping oils and proteins from the skin, I have to admit I thought all types of soap did that (with different efficiency, so I am pleased Sapo posted the question), that the ph would break down some proteins and the soap would carry off the junk and oils - I don't understand why some wouldn't. DeeAnna has been patiently trying to explain but my brain has a block in it, I think I need to learn more about different types of bonds and what all that means.
As for getting positive/negative charges wrong, that is just what my brain does to me. And with certain fatty acids stripping oils and proteins from the skin, I have to admit I thought all types of soap did that (with different efficiency, so I am pleased Sapo posted the question), that the ph would break down some proteins and the soap would carry off the junk and oils - I don't understand why some wouldn't. DeeAnna has been patiently trying to explain but my brain has a block in it, I think I need to learn more about different types of bonds and what all that means.
Seconded. Contains 90% of all you will (probably) ever want to know. Ironically, nothing in the book about what this thread is about
...unless I missed it, which is unlikely, but could happen. Almost everything else though.
Scientific Soapmaking is a good book and worth a read, but some of the things I'm talking about here come from modern soap making technology books as well as scientific papers and books. I don't know of any one reference that has it all, especially in primer form. Dunn tries to digest this heavy info and present it in a simpler, more understandable form to handcrafted soap makers, but even his book and presentations require care and attention from the audience.
"... And with certain fatty acids stripping oils and proteins from the skin, I have to admit I thought all types of soap did that..."
Not necessarily. There are shades of gray here, but I'll give an analogy to explain.
Have you ever accidentally smeared a finely powdered soap colorant on your skin -- maybe a bit of ultramarine pigment or mica -- and tried to quickly brush it off? It really sticks to the skin, doesn't it? Now think about rubbing your skin with fine sand. It would brush off fairly easily, perhaps leaving a bit of dust behind, but not much residue.
Soaps made from myristic acid and shorter fatty acids are more like the powdered colorant. Because of their small size, they are able to "stick" more easily to the proteins and fats of the stratum corneum and pull them away from the skin.
Soaps made from lauric and longer fatty acids are more like the sand, especially the longer fatty acids (palmitic, stearic, oleic, etc.) They don't chemically bond as well to the surface of the skin. They still emulsify fats and loosen soil, yes, but due to their increasingly larger size, they are not as able to stick onto fats and proteins attached to the skin and remove them.
It's important to distinguish between cleaning and irritancy. Your skin can be clean but not irritated. Or your skin can be clean but also irritated. The choice of fatty acids can make a soap less irritating or more irritating, especially for people whose skin is particularly sensitive to that kind of thing. But even folks with fairly normal not-so-sensitive skin can react to an irritating cleanser by becoming taut, dry, and flaky much quicker than if a less irritating cleanser is used.
"... And with certain fatty acids stripping oils and proteins from the skin, I have to admit I thought all types of soap did that..."
Not necessarily. There are shades of gray here, but I'll give an analogy to explain.
Have you ever accidentally smeared a finely powdered soap colorant on your skin -- maybe a bit of ultramarine pigment or mica -- and tried to quickly brush it off? It really sticks to the skin, doesn't it? Now think about rubbing your skin with fine sand. It would brush off fairly easily, perhaps leaving a bit of dust behind, but not much residue.
Soaps made from myristic acid and shorter fatty acids are more like the powdered colorant. Because of their small size, they are able to "stick" more easily to the proteins and fats of the stratum corneum and pull them away from the skin.
Soaps made from lauric and longer fatty acids are more like the sand, especially the longer fatty acids (palmitic, stearic, oleic, etc.) They don't chemically bond as well to the surface of the skin. They still emulsify fats and loosen soil, yes, but due to their increasingly larger size, they are not as able to stick onto fats and proteins attached to the skin and remove them.
It's important to distinguish between cleaning and irritancy. Your skin can be clean but not irritated. Or your skin can be clean but also irritated. The choice of fatty acids can make a soap less irritating or more irritating, especially for people whose skin is particularly sensitive to that kind of thing. But even folks with fairly normal not-so-sensitive skin can react to an irritating cleanser by becoming taut, dry, and flaky much quicker than if a less irritating cleanser is used.
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penelopejane
Well-Known Member
Dunn's book may be good for scientific minds but for someone who hasn't done chemistry st school or uni I found it pretty over the top. After struggling through if for a while I gave up and just make soap without worrying about the science behind it.
I much prefer DeeAnna's style and clear presentation of what's happening.
If you can't pick up what she's trying to say you will have no hope with Dunn's book.
In past posts DeeAnna has a run down of the different qualities of soap: hardness, cleansing etc.Much better that the various calculators whose "hardness" etc is so pathetic.
I much prefer DeeAnna's style and clear presentation of what's happening.
If you can't pick up what she's trying to say you will have no hope with Dunn's book.
In past posts DeeAnna has a run down of the different qualities of soap: hardness, cleansing etc.Much better that the various calculators whose "hardness" etc is so pathetic.
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Aha! Thanks!
Would sugar also be irritating then? I am assuming that it is also small, but I know there are many different sugars too. But maybe its action is entirely different. Or maybe I have dragged this thread on long enough. It seems silly to get worked up over something I have been using every day of my life, at the same time the chemistry of soap has some pretty amazing applications in todays world. Thanks everyone for responding to my previous posts and clearing my head a little.
* Just saw Penelope's post, DeeAnna does have a great style which I (usually) understand. I'm hoping she'll write a book one day. No pressure
Would sugar also be irritating then? I am assuming that it is also small, but I know there are many different sugars too. But maybe its action is entirely different. Or maybe I have dragged this thread on long enough. It seems silly to get worked up over something I have been using every day of my life, at the same time the chemistry of soap has some pretty amazing applications in todays world. Thanks everyone for responding to my previous posts and clearing my head a little.
* Just saw Penelope's post, DeeAnna does have a great style which I (usually) understand. I'm hoping she'll write a book one day. No pressure
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Thanks, you two. I really appreciate your encouragement!
It's my understanding that sugar does two things. First, sugar dissolved in the soapy water makes the soap bubbles a little bit stronger so the bubbles last longer. Glycerin has the same effect.
The other thing sugar does is make the soap in the bar a bit more water soluble. The soap is easier to dissolve or rub off the bar so the user gets more soap more quickly on the washcloth or hand. More soap in the soapy water means more bubbles.
You can take this too far and get unintended consequences, such as the soap bar becoming softer or "weeping" more easily in humid weather.
As far as sugar being more irritating? I don't think sugar alone would do that. Now if your soap is an irritant to begin with, adding sugar => increased solubility => increased irritancy. But that's just a guess on my part.
It's my understanding that sugar does two things. First, sugar dissolved in the soapy water makes the soap bubbles a little bit stronger so the bubbles last longer. Glycerin has the same effect.
The other thing sugar does is make the soap in the bar a bit more water soluble. The soap is easier to dissolve or rub off the bar so the user gets more soap more quickly on the washcloth or hand. More soap in the soapy water means more bubbles.
You can take this too far and get unintended consequences, such as the soap bar becoming softer or "weeping" more easily in humid weather.
As far as sugar being more irritating? I don't think sugar alone would do that. Now if your soap is an irritant to begin with, adding sugar => increased solubility => increased irritancy. But that's just a guess on my part.
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