Saturday, February 25, 2012

Humectants: A lotion maker's best friend or moisture thief?

I've always thought of February 27, 2009, as the official birthday of the blog as this is when I decided to blog every single day about some kind of bath or body thing, be it an ingredient, a recipe, or a fun fact to know and learn. One of the earlier posts was entitled Humecants are a girl's best friend, and I wrote a little bit about each humectant along with my basic recipe. A few weeks later, I wrote up a post about the chemistry of humectants - Better crafting through chemistry: Humectants. Well, it's time to revisit the topic of humectants with a lot more science and study citing (and fewer assumptions about the gender of my readers!).

The first question I want to pose to you is this...where did you get the idea that adding glycerin to lotion or hair care product could result in glycerin sucking the moisture from your skin or hair? Please provide me with information like "this forum", "this web page", "this book", and so on. If you can't remember, then saying "I can't remember..." isn't a bad thing!

Join me tomorrow as we review some skin biology so we can understand how moisturization actually works! (If you're a keener, click here as this is where we'll be starting!) Then we'll take a look at our hair and moisturization!

I realize this might not look like I'm listening to you with the whole what do you want to know post, but I thought we could use a little review about humectants, how they work, how moisturizing works, how our skin works, how our hair works, and a few other things, while taking a deeper look at humectants, which are huge in the cosmeceutical and hair care products right now! The more you know about these issues, the more power you have to analyze whether an ingredient brings what you want to your facial, body care, or hair care product! 

Related posts:
Chemistry of our skin: An overview
Chemistry of our skin: Natural moisturizing factor
Chemistry of our skin: Transepidermal water loss
Skin chemistry & types section of the blog

Chemistry of our hair: An overview
Chemistry of our hair: What does "good condition" mean?
Chemistry of our hair: What does damaged mean?
Hair care section of the blog


Valerie said...

Here is one book that states humectants may draw moisture from skin in dry environments (Links to relevant page on Googlebooks):

Cosmetic dermatology: principles and practice

Thank you so much for your blog, I learn so much!

p said...

Wooooo for understanding moisturization through skin biology! Excited for these posts!

Nancy Liedel said...

In a product you never rinse off, in the desert, not the dessert :) you can have a humectant draw the moisture from your skin and leave you feeling a little dry. In a rinse off product, it's not going to happen.

Also you can prevent water loss with an occlusive like Cocoa butter. Not as moisturizing as some people think, but it does keep things in and out nicely.

Lotion with a humectant and a nice occlusive while your skin is still damp helps in dry climates. Here in MI, we're so darn waterlogged in the summer you sweat in the shower. I want to be dry as the Gobi. Ack!!

Susan Barclay-Nichols said...

Hi Valerie! Thanks for the information! It was precisely what I was seeking!

Hi Nancy! But where did you get that information? Everybody knows that glycerin is bad for your skin when the humidity is low...but is it? What's the science behind that?

Miss E. said...

I don't have any technical references, but I have had more than one skin care educator talk about the concept of humectants drawing water to themselves, and ideally they'd do that from the environment. If the environment is arid, then the moisture source is going to be the skin. So, living in arid climate, I'm always a little wary of them in leave on products.

Anonymous said...

The reference cited in the book is to a single paper about a single substance under a single set of conditions. That is the only reference (the paper) I've ever found, and I don't believe it is correct to generalize it past the single set of circumstances it covers. I have real questions about the validity of the findings.

Chemistry in the real world isn't all or nothing. Humectants attract water from everything all the time including the air, our skin and hair. There are complex chemical equilibia occurring among these. Lowering the amount of water in air does impact the equilibrium between humectant and skin or humectant and hair, but it does not make the humectant suddenly able to overpower hair and take its moisture. Same for skin. However, in extremely dry conditions the net hydration of skin or hair MAY be reduced somewhat by humectants. This is an issue if a humectant is used and not followed by an occlusive substance, or if the occlusive is rubbed or washed away.

It may also be an issue for hair, in particular, when heat is used in drying, as one can over-dry the hair. My personal, no research to back it up, belief is that this is where the whole myth of evil silicones came from: overdried hair treated with humectants and sealed with silicone oil.

I hope someone finds another reference. I've found other books but the ones that cite a paper all cite that one paper.

Tara Wooder said...

I think that your topic about Humectant's whether it is a lotion maker's best friend or moisture thief. I know that many people are really interested about this very intriguing topic. I think that its very impossible for a lotion to be place with glycerin but I know that many people would love to know more about it.

Susan Barclay-Nichols said...

I've written a post on this topic - does glycerin draw water from your skin in drier environments? - so check that out!