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Composition of acid mantle and how is it made
According to google, when sebum is mixed with sweat, it makes the acid mantle.
As i don’t trust google
i want to learn the answer to these questions from you chemists.Questions:
1. What is the composition acid mantle and how is it made?2. If it is mixture of sebum and sweat, then if we wash our skin daily or twice a day with surfactant, does it means we have no acid mantle because we remove all the sebum and sweat?
3. Even if we wash our skin with water alone that removes sweat but not sebum, does it mean we don’t have acid mantle because sebum alone doesn’t make acid mantle?
4. Those parts of our skin that doesn’t produce sebum, do they ahave acid mantle? If yes then how?
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17 Replies
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@Abdullah
The questions you ask deserve the whole article or books.
You will find all the answers here: -
@vitalys thanks for all these links. You are a generous soul and tribute to the science of personal care.
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chemicalmatt said:@vitalys thanks for all these links. You are a generous soul and tribute to the science of personal care.You hit the nail on the head. Vitaly is an asset to this community, and the world.
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@vitalys thanks a lot.
I wasn’t available for some days.
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@chemicalmatt @Graillotion Thank you for the kind words, dear colleagues. It is just a small part of the skin knowledge, which is always useful in cosmetic formulating work.
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@Abdullah you are very welcome
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A chemist here once told me that skin and hair doesn’t have pH. The have isoelectric point.
Skin isoelectric point is ~4.8
Hair isoelectric point is ~3.6These papers all say skin pH is this and that.
Maybe i haven’t understood it correctly so i am asking it once again.
does skin have pH?
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@Abdullah
Certainly, it has pH, because isoelectric point (IEP or pl) is pH. -
@vitalys - Perhaps it is semantics but pH is a measure of the amount of [H+] ions in a water solution. For something to have a pH it has to be liquid by definition. Skin is not a water solution, thus it does not have a pH any more than a chair, a table, or a refrigerator has a pH. Am I missing something?
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@Perry Epidermis and especially dermis contain water, i.e., water solution of electrolytes, etc. It means that pH is measurable. I must say even more - pH is a key factor to make multiple enzymes work, which is important for instance for such physiological processes as proper keratinization or lipid formation in keratinocytes. Skin even contains the special proteins for the water transportation - aquaporins.
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@vitalys what about Stratum Corneum? Does it have water? Because this is the outermost layer and what will be in contact with cosmetic products.
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@Abdullah Yes SC is hydrated, which means it contains water to some limited extend. SC is highly dynamic structure. The hydration of SC defines the local homeostasis of SC, the proper structures of the lipid bilayers and the degree of this hydration depends on the blood microcirculation in the upped dermis and the outer humidity and environment.
The SC water content and water retaining capacity of corneocytes and NMF depends on different skin conditions or skin pathologies too. See the picture attached.
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@vitalys thanks
Is this photo from a book? -
@Abdullah Sorry I didn’t mention the source.
Masanori Takenouchi, M.S., Hiroyuki Suzuki, and Hachiro Tagami, M.D. “Hydration Characteristics of Pathologic Stratum
Corneum-Evaluation of Bound Water” Department of Dermatology, Tohoku University (HT), Sendai, Japan -
Here’s the link - https://www.jidonline.org/article/0022-202X(86)90008-4/pdf
I’d not get carried - no standard deviation in this or Fig 1. -
PhilGeis said:Here’s the link - https://www.jidonline.org/article/0022-202X(86)90008-4/pdf
I’d not get carried - no standard deviation in this or Fig 1.It says This page does not exist.
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