What chemical ingredients in the various soaps we use enhance or inhibit continued hydration of the beard during the shave?
Soaps and hydration
- Thread starter Ron Scott
- Start date
Enhancement is usually a task performed by the glycerin that is part of the soap and a by product of saponification process. Many soaps add even more to increase the benefits it has for the hydration and lubrication of your beard and skin.
http://badgerandblade.com/vb/showthread.php/123578-Anyone-got-a-microscope?p=1719413#post1719413 might interest you, and perhaps some of the other links at Science_Of_Shaving.
The magic chemicals are water and soap. Soap is good at breaking through the acidic layer that normally protects hair and skin. But the real magic is the structure of the lather, which holds water close to the hair and skin so that both can absorb it.
The magic chemicals are water and soap. Soap is good at breaking through the acidic layer that normally protects hair and skin. But the real magic is the structure of the lather, which holds water close to the hair and skin so that both can absorb it.
From what I know, no ingredient or quality of shaving soap will increase or decrease the amount of hydration. Not in a meaningful way. At best, they slightly change the speed at which hair gets wet. So do temperature and pH. Strictly speaking, they don't change the speed, but they lower the levels of wetness at which different modes of wetting operate. (Let's call these modes dry, damp, and wet. It's easier to get water into something that's damp than something that's dry, and even easier to add water to something already very wet. So each mode soaks up water faster than the one before. If the next phase begins when there's less water, the tap gets turned up that much sooner.)
Soap cleans oils off the surface, but that doesn't seem to matter for shaving. As long as some part of the hair gets wet, the water will eventually soak through. But other stuff doesn't soak through the hair. This matters if you're coloring hair (using certain processes, anyway) because the color won't get past dirty/oily surfaces, and most things can't freely travel through the interior. But water (and some probably some very limited solutions) will travel through from one side to the other, just like it gets through all the other parts of us.
Soap is a surfactant which means it's also a wetting agent. This gets the water closer to the surface of hair. (Remember the wetting modes? This is the main property of soap that alters where the modes change.) This makes water soak through easier.
The glycerin in soap is an even better humectant that can hold onto a lot of water. More glycerin should mean more water in the lather and more to get into the hair. Then again, that same humectant property also helps remove that water faster as the lather dries out. Some soaps use wax (e.g. lanolin) that serve a similar purpose. Some even add oil that mostly prevents water from seeping back out of hair.
Of course, any of these ingredients might also serve other purposes than hydration, such as protection and lubrication. Glycerin and lanolin are emollients (moisturizer), as is any oil or fat. Any of these might prevent your beard from drying out--assuming you managed to get it hydrated in the first place. Of course, no decent shaving soap is going to have so much that it won't wet your beard. But some creams might.
Soap is also an emulsifier, which stabilizes lather, but other stabilizers are sometimes added to help make a more stable lather because a good, stable lather can hold more water.
There's a lot more going on, but it's more important for creams and gels. (And this is already way over my head.) Soaps are mostly simpler. Specifically, creams and gels might have ingredients that interact better with proteins, or use detergents that perform better than soaps with hard water, etc. (You should also realize that every fatty acid has its own affinity for water and other elements. But detergents offer a lot more variety.) In fact, many gels & canned goos don't even bother with hydration, and rely strictly on lubricating. I'm sure some soaps have some of those ingredients.
BTW, I'm not a chemist, but I play one on B&B
Soap cleans oils off the surface, but that doesn't seem to matter for shaving. As long as some part of the hair gets wet, the water will eventually soak through. But other stuff doesn't soak through the hair. This matters if you're coloring hair (using certain processes, anyway) because the color won't get past dirty/oily surfaces, and most things can't freely travel through the interior. But water (and some probably some very limited solutions) will travel through from one side to the other, just like it gets through all the other parts of us.
Soap is a surfactant which means it's also a wetting agent. This gets the water closer to the surface of hair. (Remember the wetting modes? This is the main property of soap that alters where the modes change.) This makes water soak through easier.
The glycerin in soap is an even better humectant that can hold onto a lot of water. More glycerin should mean more water in the lather and more to get into the hair. Then again, that same humectant property also helps remove that water faster as the lather dries out. Some soaps use wax (e.g. lanolin) that serve a similar purpose. Some even add oil that mostly prevents water from seeping back out of hair.
Of course, any of these ingredients might also serve other purposes than hydration, such as protection and lubrication. Glycerin and lanolin are emollients (moisturizer), as is any oil or fat. Any of these might prevent your beard from drying out--assuming you managed to get it hydrated in the first place. Of course, no decent shaving soap is going to have so much that it won't wet your beard. But some creams might.
Soap is also an emulsifier, which stabilizes lather, but other stabilizers are sometimes added to help make a more stable lather because a good, stable lather can hold more water.
There's a lot more going on, but it's more important for creams and gels. (And this is already way over my head.) Soaps are mostly simpler. Specifically, creams and gels might have ingredients that interact better with proteins, or use detergents that perform better than soaps with hard water, etc. (You should also realize that every fatty acid has its own affinity for water and other elements. But detergents offer a lot more variety.) In fact, many gels & canned goos don't even bother with hydration, and rely strictly on lubricating. I'm sure some soaps have some of those ingredients.
BTW, I'm not a chemist, but I play one on B&B
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