Sunday, February 22, 2015

Glycerin and Humidity

Cindy asks a winter inspired question from frigid Wisconsin where humectants are making the winter of 2014-2015 even more frustrating. You need to know that here in the Midwestern U.S.A. (like Wisconsin), winter tends to be very cold and very dry. So even when we see the outdoor humidity is, say, 50%, if the temperature is 10°F (-12°C), the air is still extremely dry and the dewpoint - that temperature indicating how much water the air could hold if it was fully saturated - could be below 0°F. That is desert-dry air.

I zero in on glycerin because it can be a curly or wavy-haired person's dry-air nemesis. But I didn't leave many out, so read on. "Humectant" is a very broad category including salts, glycerin, plant gels like aloe vera or flax gel, algae extracts, hyaluronic acid, hydrolyzed proteins, sodium PCA, lactic acid, urea, witch hazel (without alcohol) and other ingredients that attract water. Not all humectants are "created" equal - different humectants behave differently in hair. I think when people complain about humectants, they are having the most trouble with simple humectants like: glycerin, propylene glycol, sorbitol.

Humectants attract water to themselves. Humectants like glycerin are great at grabbing water vapor out of the air. When you have a hair gel with glycerin in it, when there is ample water in the air (humidity) - the air is going to be hydrating the glycerin in the product, which is going to help your hair stay hydrated. Well-hydrated hair has more bounce and definition. A second benefit of glycerin in products (when there is ample water vapor in the air) is that glycerin keeps hold-providing ingredients that would otherwise create a brittle, candy-like finish from feeling brittle and candy-like. Glycerin (and sorbitol and propylene glycol) take water vapor from the air to hydrate the dry gel in your hair and keep it more flexible.

When there isn't enough water vapor in the air (low humidity and/or low dewpoints), the gel loses that benefit from the glycerin and the gel becomes more brittle, creates friction and that means hair that feels dry and crusty and looks dull.

Whether humectants actually dehydrate the hair - pull water from the hair is not well-studied. And it is an "it all depends" sort of question. It is based on a reasonable hypothesis; that if glycerin attracts water from the air, when the air is drier than your hair, water will move from your hair to the glycerin. For that matter, when the air is less humid than the inside of your hair - the water will tend to move from your hair to the air around it - glycerin or not. So does glycerin create a stronger "pull" (water gradient) than dry air alone? It probably does exert a stronger pull on the water in your hair than dry air alone. But not all humectants do that. Think of glycerin like brown sugar. In humid air, a bag or tin of brown sugar absorbs moisture and forms clumps. But it dries out quickly too and the clumps become hard as a result.

Don't discount the effect of that dehydrated gel sitting on your hair because 1) glycerin can't pull enough water out of your hair to keep a gel from getting brittle and 2) brittle gel creates friction - that means rough, tacky hair that frizzes when it contacts other hairs and objects and snags at cuticle edges. A crusty, dehydrated product in your hair is bad news for how your hair looks and feels.

Mitigating circumstances
If you used oil or leave-in conditioner under a glycerin-containing product, that layer of emollients would slow down water loss from hair. If there are other humectants that are not a ready to give up their water as glycerin in the same product, the effect might be reduced. Oils and conditioners act as "occlusives" - the layer of oil or leave-in conditioner is not water-soluble and that helps slow the movement of water in and out of hair.

Why glycerin, why must you be so fickle?
To get to the heart of why glycerin can be a problem ingredient for some people in some weather, one big issue is the size of the molecule. The smaller the molecule, the less water it can bind and hang on to when exposed to very dry air. Glycerin, sorbitol and propylene glycol are "sugar alcohols" - not alcohol like the kind used in hairspray. They are small molecules. There are not a lot of places on the molecule to bind water. Think of glycerin as a "simple sugar" as you would think of candy. Sure, glycerin and sorbitol and propylene glycol aggressively pull water to themselves, but they also lose it fairly easily. Emollients (oils and conditioners) can slow that down, but not stop it. So when the air is very dry - glycerin is a much less effective ingredient. Glycerin is a fair-weather friend. When the humidity is just right, glycerin can help your hair look and feel great. When the weather gets too dry, glycerin can't pull enough water to itself and it loses it's effectiveness. When the air is very humid and glycerin pulls lots and lots of water in - poof - your hair loses definition. 
Glycerin is a small molecule and not
very complex.

Formulation can be a problem
Often, a problem with a glycerin-containing product is that it uses only glycerin for a humectant and "flexibilizer" and does't use any emollients or film-forming humectants at all. Well-balanced products avoid this pitfall. Different humectants have different actions and a combination of different size and molecular weight humectants might be okay for a person who finds that just glycerin and no emollients or film-formers is a mess.

Is it just me?
There are people who live in climates that are dry year-round and use glycerin with no problems at all. And there are people who can only use glycerin when the humidity is "just right." There is no simple rule to determine how your hair will respond because it's not just a porosity issue. It's an issue of climate and weather, what other products you use in your hair, how sensitive your hair is to increased friction, how often you go outdoors. Trial and error. As usual. 

Is there a winter-proof (dry-weather-proof) humectant?
A great big molecule like the complex carbohydrates in flax seed gel or hydrolyzed proteins behave differently in hair than glycerin. These ingredients don't rely heavily on water vapor to work well. They don't have aggressive water-grabbing force. They're more subtle. There are many places to bind water in these molecules. Not only that, but they also form clear, flexible films over your hair. Water-hugging films that tend to slow water loss from the hair. If these large, moisture-retaining humectants which I call "film-forming humectants" are combined with oils or conditioning ingredients in a styling product, the humectants and oils and/or conditioning ingredients combine to actively attract and hold water and slow water loss, providing longer-lasting hydration and lubrication. The link in the previous sentence takes you to a list of film-forming humectants.
One of the many complex carbohydrates
in flax and other plant gels. It is a larger
molecule and more complex, capable of
forming water-hugging films.

Hair that cannot tolerate simple humectants like glycerin or propylene glycol may still do well with film-forming humectants in styling products. What we want from styling products is extremely personal. If you are looking for hold or definition, these are some styling products which may work:

AG Weightless Volumizer
AG Mousse Gel
AG Re:Coil
Aussie Real Volume Mousse
Aussie Instant Freeze Gel
Camille Rose Aloe Whipped Butter Gel
Curl Junkie Curl Queen
Curl Junkie Pattern Pusha
Biosilk Rock Hard Gelle
Darcy's Botanicals Curling Cream Gel
DevaCurl Set Up and Above
Goddess Curls Gel
Herbal Essences Totally Twisted Curl Scrunching Gel
Herbal Essences Set Me Up Gel
Herbal Essences Naked Volumizing Souffle
Jessicurl Confident Coils Styling Solution
LA Looks Nutra Curl Moisturizing Gel
Salon Care Aloe Vera Styling Gel
Pantene Pro-V Stylers Max Hold or Strong Hold Gel

For products that are based on film-forming humectants, including many natural and plant-based gels, go to  this page on this blog and scroll down to the list of products including film-forming humectants. Some contain glycerin - check the ingredient lists. Most are light to medium hold and can be topped with a gel with stronger hold, like Biosilk Rock Hard Gelee (from the above list) if necessary.

Why are plant-based, film-forming humectants less "fickle?" Stuff about plants.
Flax seed is an example. The gel comes from water contacting the seed. Seeds do this so that when they are in the soil and the soil is moist, the seed can attract water, form that gel which assures the seed will stay moist enough to sprout. If a seed gets wet, begins to sprout and then dries out, it dies. So this is a brilliant adaptive strategy to assure seeds sprout to create new plants and more seeds.

With aloe vera, that is a desert plant. It has thick, leathery leaves with spines on them to discourage animals from eating the juicy leaves and to prevent water loss. The gel in the inner leaf does not dry out quickly, a good strategy for a desert plant.


  1. Thank you so much for taking on this topic. You made the confusing subject of humectants, emollants and the weather a lot more clear. I have ordered the Jessicurl Confident Coils, so my fingers are crossed that it works okay.

  2. Hi great article. Was wondering why Deva products either make my hair great or not so great. I'm pretty convinced it's the high content of glycerin in them. I live in Philly and there's only short periods where the humidity is just right and it's not often.

    As far as ingredients except for the glycerin the Deva Delight line is good. I like that it has protein in them. But the glycerin is the killer.

    Do you know of any products similar to Deva Delight that are glycerin free or glycerin being very low on the list? Thanks!

    1. You may be right about the glycerin. There are also some other ingredients that can leave a strange feel in hair or create frizz, but usually the formula as a whole determines whether this or that ingredient is a problem.
      You might check the page in the tabs at the top of the blog "Products List By Category" - and see the first list of conditioners for hair that needs lubrication/slip. Then also look at the list of products with protein (conditioners) and see if there are any glycerin-free products that look promising.

  3. Great blog! I am trying to test out a glycerin free regimen and see if it helps my hair. Was wondering if I had to eradicate all humectants but I'll leave them in for now. Thanks!

    1. Glad you enjoy the blog! Glycerin is one of the humectants that gains and loses moisture readily. Other humectants that behave like that are propylene glycol, sorbitol, agave nectar and honey.
      But if you want to eliminate all "humidity-fickle" humectants for a while - those would be the ones to focus on. But not all of them may be a problem. And a lot of how those ingredients behave depends on the formula of a product as a whole.
      Other humectants like panthenol, Sodium PCA, animo acids and proteins, aloe, flax, pectin, Irish moss, algae extract, are less like glycerin and slow down water loss from inside the hair. Those tend to be useful humectants in all weather for maintaining hydration. Best wishes - W

  4. Thank you for this informative article! It seems that all humectants and being sensitive to botanicals are making my curls frizz this summer, its been brutal :( Do you have any suggestions in styling products?

  5. If I use 1/2 teaspoon of plain sugar in a diy flax seed gel to hair style in high dew point hot, humid weather. The sugar would make my hair frizz?

    1. Hello Rocio,
      Sugar tends to absorb water from the air very quickly. It may or may not make hair frizz, but it will change when you move from more humid to less humid areas (indoors, outdoors).

  6. How about plain sugar? Would it create frizz in hot humid weather?

  7. Gray hair on my mother in law bottom half is Yellow. Shoulder length hair. Dementia is her only 86 year old problem. I suspect withholding meds? What could cause this on Lower half? Flummoxed I am! Help!

    1. Hello - this post may be helpful.

  8. Oh, Wendy, I sure hope you can help me out on this somewhat unusual request. What I'm about to divulge to you breaks my heart, and I sure hope you can help me break this down...

    So, I have this good friend of mine, who is white (we'll call her F), and her brother, who is also white (we'll call him B), has a girlfriend who is black (we'll call her G). G and B have a daughter (we'll call her J), who is about 11 years old.

    J primarily lives with her grandmother/F's mom (whom we'll call A).

    There is a reason I am including race, and I'll get to it in a second.

    So, here's the nitty gritty: F, A, and J are all in support of J going natural and embracing her curls, and, furthermore, adhering to the curly girl method.

    The problem is that G is dead-set against NOT continuing to put basically a pound of straight-up/old school grease on J's hair. Here's the plea F just sent to me, verbatim: "I’m at my moms and we just had dinner and my nieces mom (G) is here. The convo turned to J’s hair for a sec and things almost got heated. My mom said something and my nieces mom (G) said “well, she’s African American, she NEEDS grease in her hair!!!” Do you have any articles or any info I could try to share with her on this? Her and my mom go back and forth on this all the time and I wish I could help."

    Here's the deal: G thinks F and A don't know what they're talking about because G is black, she thinks she is the authority on black hair...simply because she is black. G, however, does not even properly care for her own hair, nor has she worn her own hair natural.

    G is a prime example of someone who is under the spell of cultural conditioning: Seemingly from the beginning of time, (I'm not going to say all, but certainly many) black women have been essentially told how to "care" for their hair...but most were not given scientifically-based info on how what they are doing affects their hair. We were culturally conditioned to believe our hair looks better straight...we were culturally conditioned to believe that we HAD to apply thick oil to our scalp and all along the strands of our hair, etc...Trust me, I'm not throwing shade. I've lived through this, too.

    Now, of course, if you're trying to maintain straight hair--when your hair is not naturally straight--that oil provides an excellent barrier, preventing moisture from getting in...which helps keeps your hair straight.

    But what many women fail to understand is that the barrier created by oil is no bueno for curls. And, I get it, this is hard for some women to digest--especially when we were not taught this as kids.

    And to make matters worse for G, she feels resentful that two white women are telling her the opposite of what she believes to be true.

    Anyhoo, F reached out to me via the message (above), and I immediately thought of you.

    Can you please provide an easily understandable scientific explaination why black hair does NOT need grease (particularly if the aim is to maintain healthy curls) and why getting water into strands is so crucial?

    Thank you so very much for your time!

    ps, I'm looking to do a YouTube vid on this and would like to reference your reply, if I have your blessing. <3

    1. Hi Courtney! This is late because I have not been able to get my comments to load. In old photos and movies - people LOVED the pomade. All that hair since the beginning of movies until the 1940s or 50s was styled with oil-based pomade to get the shape right. Before modern hair gels - oil-based pomade-type products were pretty much all there was for styling. Pomade and grease wasn’t necessarily meant for hair-health as much as for aesthetic purposes. That is a relevant point from the whole "curly girl" idea - making sure hair is healthy in order to look nice, rather than to make it look “right” without regard for it’s long-term health.

      I do have some references for you, but they’re textbook ones - from “The Chemical And Physical Behavior of Human Hair” the elastic and tensile deformation of hair (hair that bends, stretches a little), hair is always tested for tensile strength and cuticle damage upon stretching at a controlled humidity in a lab setting. That is because at higher relative humidity, hair contains more water and that affects its stretch. At 65% relative humidity - hairs have higher elasticity (and even higher when they are stretched in water - which is 100% relative humidity). Whereas if you are testing those hairs’ stretch at lower relative humidity (45-50%), they stretch less before damage or breakage occurs. *** The very first graph on this page shows how much more water hair holds at different relative humidities. On the left/upright side is the relative humidity, and on the bottom is the percent water content in hair.

      I do elasticity testing of hair which is dry and hair soaked in water for several minutes to fully hydrate. Wet hair that is healthy tends to stretch about 20% more than when it was dry. To me - that’s what hydration is good for. Strength in hair both when wet and dry. The ability to stretch a little, but not break. And that’s why we need water-based products as well as oils and emollients. Hydration adds one kind of flexibility, oils and oily products add a different sort of flexibility.

      Using oils or emollients or grease alone is like oiling leather to keep it soft. But one might also end up with dehydration if 1) One uses too much oil for their hair and 2) the oils are not washed out so the hair can re-hydrate in the allotted shower or bath-time - lack of hydration creates inflexibility.

      This post from Natural Haven is helpful - about shampooing to remove oils and grease, and then during conditioning - the second little graphic shows that water can get into the hair (along with other things).
      I like her post on silicones and mineral oil, too. It doesn’t support your point completely, but the take-away from so many of her blog posts is something like, “All things in moderation.”

      Everybody involved needs to feel heard and respected. I do hair analyses for people who are trying to reconcile (at ages 20, 30, 40, 50, 60+) the hair care they learned from mothers and grandmothers, which fit a different era as well as different kinds of hair and hair products. It gets complicated and emotional! Moms and grandmothers (and aunts) want to be an expert and pass on what they know and see themselves reflected in that child. There are hydration-promoting products with great ingredients which can do the job of hair grease, but with humectants as well as emollients, like CURLS Blueberry Bliss Control Paste (or Passion Fruit Control Paste), As I Am Naturally Smoothing Gel. Products like this go well as a top (last) layer with a leave-in conditioner (water-based for hydration), and/or a gel or curl cream, and a little oil for hair that is dry or needs flexibility - then the curl paste or smoothing gel on top. It’s a possible compromise to substitute some water-based products for the plant oil or mineral oil based products.
      Best wishes- Wendy

  9. Oh, Wendy. I am SO appreciative of your taking the time to reply in the manner in which you did: Thank you, particularly for the detail. Every bit will be helpful. I'll pass this on to my friend right now...



  10. Hi Wendy, I think that my ends dislikes glycerin (and maybe similar humectants) because I tested it with Braid Sheen Spray which has highly concentrated propylene glycol and glycerin.
    But do fruit/herbal/plant extracts contain glycerin when included as ingredients in products?

    1. Hi Sera,
      Some plant extracts are made in a water and glycerin base, some are not. Most plant extracts are used at around 1%, so if the base was 50% glycerin, the total amount of glycerin added to the product by that plant extract might be 0.5% - which is not much, but enough to have a humectant effect. Product labels are not required to include components like glycerin or preservatives in their plant additives, so this is not information you will find on a product label.

  11. It's been a while since the list was published. Biosilk Rock Hard Gelle has been my go to for years but the formula has changed. I've tried several different products trying to match the hold level it provided but haven't come close. Beyond the Zone Bada Bing Extreme Hold is kind of close and works well in the winter, but not great in the humid months. I feel like it has a film of some sort that might prevent the hold level needed. It's kind of strange to be honest. Since your post, have you come across any other products that might compare to the BRHG?

    1. Hello AWest - I know of two that might be comprable for humidity-resistance. Not sure they'd have the intense level of hold that Biosilk Rock Hard Gelee had. Schwarzkopf Amino-Q Hold Gel for ultra hold, and It's a 10 Miracle Hold Gel. The latter is not silicone-free, but Amodimethicone is not as heavy as some silicones, and it acts like a conditioner, bonding only to damaged areas. In other words - it tends to wash out well and any left behind is bonded to chipped cuticle edges (just like conditioners do).