Thursday, March 6, 2014

Managing Elasticity and Porosity in Hair

Managing Elasticity and Porosity: "How To" and a little of the science behind it.

Elasticity is a hair character or property that overlaps with porosity. Human hair is elastic - it stretches a little. It stretches a bit more when wet than when dry when it is well cared for. If we over-stretch our hair, it will be damaged. But hair that stretches rather than breaks is a good thing because it's still there to protect our heads.©Science-y Hair Blog 2014

When hair is dehydrated, it loses it's elasticity, its "stretch." Think of leather or rubber or wood left in the sun and wind for a long time. It becomes dehydrated, loses it's flexibility and becomes brittle.

When hair is porous, it loses water more rapidly than is good for it. Hair can be porous because it has been out under the sun a lot, as a result of frequent washing or wetting or lots of brushing, from hair dye or highlights or swimming pools or chemical relaxers or permanent waves or high heat styling, from daily wear and tear or abrasive styling products.

If hair loses water too quickly, it becomes dehydrated. Dehydrated hair is less elastic. Elasticity, porosity and your regional weather are closely related. Even the healthiest of hair gets dehydrated when the air is very dry.

We need to define hydrated hair. Hydration for this purpose means containing adequate water. Hair is more hydrated when the air around it is humid because hair takes up water from the air around it. Hair is less hydrated when the air is very dry.

Porosity works into elasticity and hydration thus: The more "weathered" your hair is as a result of length (more time exposed to the elements), sunlight exposure, mechanical damage (brushing, styling) heat exposure, chemical exposure (peroxide, ammonia, pool chlorine, salt, acids and alkalis), the more porous is probably is. Especially on the ends.©Science-y Hair Blog 2014

Porous hair readily gains and loses water to the air around it because it is no longer protected by a tight seal of cuticles.

Because porous hair hydrates and dehydrates easily, it is difficult to maintain good elasticity. It is simply too weathered.©Science-y Hair Blog 2014

Elasticity in all hair helps prevent breakage when hair is manipulated - detangled, styled, slept on. Good elasticity in wavy and curly and coily hair helps support a strong wave pattern that returns when manipulated. Elasticity is part of the equation that helps reduce breakage.

One thing I have seen in the process of doing hair analysis is that hair often has normal elasticity when dry, but low elasticity when wet. Most of us know that wet hair is more fragile because it stretches more and because has extra friction between the wet strands. But I was surprised by this result. So I tested some people's hair I know to be very healthy and well cared for and got a "normal" result. I'm finding that low wet elasticity and normal dry elasticity correlate with hair that needs extra help staying hydrated - keeping the right amount of water in the hair.

So how do we keep our hair hydrated? Here are some simple ways to keep your hair hydrated to improve elasticity and manage porosity. It's not difficult to understand when you know some of the science behind it and when you pay close attention to your hair's response to these things. Nothing matters more for hair care than paying attention to how your hair responds!

1) Prevent swelling and dehydration and friction that occurs in wet hair and during washing.

Your hair has its cuticle layer which appears like 4 to11 layers of thin fingernails. The cuticles overlap like shingles or tiles on a roof - keeping water out when they are well intact. Cuticles are linked to each other, making this entire outer "cuticle shell" brittle. It really is like shingles on a roof - it can cover and even turn corners on hair - but it cannot increase in girth and still maintain integrity. 

Cuticle shown in yellow, endocuticle in blue,
cortex in red.

Turquoise arrows at left show the direction
of force as the endocuticle swells in water.

The layer beneath your cuticle, the endocuticle can swell a lot in water. If your hair is all lower porosity - the water doesn't get to this layer very easily. But when and where your hair is normal porosity to porous, water can get to this layer and it swells with water. The stress of hair-washing comes from the swelling layer beneath a non-swelling layer. As the expandable endocuticle swells beneath the cuticles, it increases in girth and exerts force outward, on the cuticle shell. As a result, cuticles are strained and stand away from the hair. In this state, they are more easily broken off. And so you have protein loss resulting from broken cuticles! Cuticles in this vulnerable position break from rubbing on other hairs, from wet combing or detangling while wet.
This is a porous area in a hair in water. The cuticles
are pushed out from force beneath as the endocuticle
swells with water. In this position, the cuticles are
more vulnerable to chipping and breakage which
causes loss of protein from the hair and further
increases porosity.

I'll add that shampoos which are too strong because they contain strong detergents or because they contain too high a concentration of detergent, and often acids like vinegar and bases like baking soda or soap bars tend to make hair swell more rapidly than plain water. All the more reason to pre-treat your hair!
This is a porous hair swelling rapidly in baking soda
solution. Not all hair reacts this violently.

How to prevent this:

- Pre-shampoo penetrating oil treatments
- Pre-shampoo conditioner application

Of these two options, the pre-shampoo penetrating oil treatment is the best-studied to address the swelling and protein loss and the "waterlogging" of too much swelling in water. Coconut oil has the best record for addressing these problems effectively, especially in bleached and damaged hair. But other oils may be similarly or adequately effective if coconut oil is too heavy for your hair or irritates your skin.

Leave a pre-shampoo oil treatment on for at least a few hours. 8 hours is the amount of time used in the study I'm citing below. Read more at the end of this post to find out how a pre-shampoo oil treatment works to protect your hair from damage during washing.

Conditioner before washing doesn't deeply protect the hair from swelling, but it does protect the hair from some of the water hitting it and occupy the detergent in a shampoo.  Cetrimonium bromide is an exception, it has been demonstrated to penetrate beyond the cuticles.

2) Prevent water loss from hair the rest of the time.
There are 2 ways you can do this, and you can do both at the same time, it involves products left in and on the hair.©Science-y Hair Blog 2014

A)  Water-soluble (non-oily) films that are flexible, invisible and yet water-protecting
B)  Water-insoluble (oily) films that slow water loss because they are not penetrable by water - oils and leave-in conditioners

Water soluble films can be formed by proteins, plant gums like flaxseed or okra, celluloses, pectin or carbohydrates, panthenol, hydroxypropyltrimonium honey. If you were to spread these on your skin, they would dry to a clear film. They would not be impenetrable to water - for example if you sweat, your sweat would pass through and also wet the film. These films act as a barrier to excessive water loss. Hydrolyzed proteins are water-loving and slow the evaporation of water from your (dry) hair. Not everybody's hair does well with proteins, but there are non-protein options in that list. This post has more about whose hair may do better with protein.©Science-y Hair Blog 2014

Water-insoluble films are provided by leave-in conditioners and oils you use on your hair. Oils on damp hair and leave-in conditioners on damp hair form a waterproof barrier to keep water from escaping too quickly. If your hair can tolerate oil without getting limp or greasy - oils can seal in the moisture on your hair and slow that moisture's escape into the air around it.

Oil on dry hair? That doesn't hydrate. That softens. It lubricates. Oil is water-free - so it can't hydrate or moisturize (not literally, anyway) and that's okay because hair there's a lot more to hair care than water.

3) Protect the hair to prevent water loss
Don't use high heat. Or at least not without a heat protectant.
Protect your hair from the full sun if you're out for a long time.
Protect your hair from dry, windy weather - wear a scarf or a hat you can pull your hair into. Tie your hair back if it is long so it does not blow around and use a little leave-in conditioner on it as you tie it back.©Science-y Hair Blog 2014

4) Deep treat
Protein treatments for people whose hair appreciates (or tolerates) protein
Deep conditioning for people whose hair needs extra softening and more flexibility

When you use protein or intense conditioner or both wither left on for 5-30 minutes with heat, more of the active ingredients interact with your hair and remain on your hair for a better result. Here is a link to Part I of a 2-part post about deep conditioning.

How does a coconut oil pre-wash do this? Coconut oil has been shown (using ridiculously expensive equipment) to penetrate beyond the cuticles thanks to its triglyceride content and small fatty acids. Coconut oil is attracted to the inner part of your hair. Coconut oil has a couple different effects - the first effect is not unique to coconut oil.
1) Blocks water from getting into the hair - like most oils do.
2) During washing, some coconut oil gets into the hair fiber as it is being washed. Because oil repels water, when it is introduced to the interior of the hair (which ordinarily attracts water), it makes the inside of the hair water-repellant so it swells less.
Less swelling means the cuticles won't be lifted up where they are easily broken off which means that all those proteins that belong to the cuticle won't be lost, your hair won't be waterlogged and I should add that your hair will feel soft and lovely after you wash it.

The effect is more obvious on damaged, porous and especially bleached hair (highlights, lightener, permanent color) and less obvious on lower porosity hair.

The effect of coconut oil is less if its applied to hair after washing than if applied as a pre-shampoo treatment.

What if I hate coconut oil? Palm kernel oil, sunflower oil and Ucuuba butter penetrate the hair and would be good substitutes for coconut oil. To a lesser extent, olive oil, avocado oil, castor oil, argan oil and other seed oils give you some of the protection from washing, but they may not have the same waterproofing effect on the interior of the hair as coconut oil. 
I use an oil mixture in my lower porosity hair and as far as I'm concerned, it's better in my hair than straight coconut oil which is too heavy for me and makes my hair a little rigid. Here is a link to a post about making pre-shampoo oil treatments work for your hair.
©Science-y Hair Blog 2014
In this post, olive oil did not protect the hair as long in chlorinated water as coconut oil and I suspect that is because the polar coconut oil is attracted to the hair proteins (it can get into the hair) in addition to forming an oil film over the hair surface.

You'll notice that conditioner protected the hair from the chlorinated water very well too - so if oil is just not your thing - a pre-shampoo application of conditioner, known colloquially as "condition-wash-condition" might do the trick.

AARTI S. RELE and R. B. MOHILE, 2003
Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage. Journal of Cosmetic Science, 54, 175-192 


  1. I'm all for pre shampoo protection, however my fine hair is very prone to buildup. How does pre-poo treatment affect the removal of buildup?

  2. I think it depends upon the sort of build up. If you have build up of creamy products or oils or silicone ingredients, the oil pre-shampoo might make it more difficult to remove those things. I don't think it should make much difference if you're removing other, non-oily residues. With the exception of products that leave build-up that makes your hair too soft. The oil pre-shampoo with soften your hair too and then it will be overly soft.

  3. Hi!

    It seems like commenting via the phone didn't work (ugh), so I'm gonna try again - if I now wrote double, sorry!

    What do you think about the "squish to condish"-method? ( What made me wonder was the fact that she talks about swelling the hair when it's dehydrated to get moisture in there, then sealing the whole thing with conditioner.

    I get amazing hair with the method. It's soft, it's silky, it's defined like nothing else. I'm worried though, because it tangles overnight and feels dryish then. If I fingercomb to test, it feels silky again. Still tangly, though.

    It might be my anti dandruff shampoo, which is pretty harsh. I'm replacing it by normal curl friendly shampoo with tea trea oil starting today to see if it will make my scalp manageable without angering the frizzgods.....
    But, I'm still worried squishing will kill my hair over time... Any thoughts?

    Thank you!

  4. Hi Zaunfink,
    The method described there works really well, though some of us (ahem!) cannot use that much conditioner. Ever. Squeezing the hair into shape while conditioning and rinsing begins the "hair-setting" process. Hair naturally absorbs water.

    Having our hair swell in water is stressful, which is why this post deals with ways to reduce that. But a full wetting of at least 2 minutes re-hydrates hair that may be dehydrated from dry weather (hot or cold), hair dryers, hot sun, or indoor air conditioning.
    If your hair is feeling tangled when you use this method, despite also feeling soft and silky, a few things come to mind. One is that you are getting build-up from the conditioner or that it's just too much conditioner. I have a couple posts about that like this one:
    Conditioner build-up tends to feel matted and tangly and look a little dull. Over-conditioned hair, on the other hand often feels very soft and silky, but it tends to be limp and lose volume and ultimately, loses curl definition.
    You might try rinsing some of the conditioner out to see if it reduces the tangles - or try switching conditioners in case the one you are using is causing build-up

    Hope that helps!

  5. What are you suggestions for daily rehydration of (porous) kinking hair between the washes? (oils are fine by me)

    1. Hello Sera,
      If hair doesn't shrink a great deal when wet (as tightly coiled hair does) then between-washing rehydration could be something as simple as mixing together some distilled water, conditioner, a little aloe vera juice if your hair likes it, a little oil in a spray bottle and moistening your hair with that. That gives you water for hydration, conditioner (and oils) for softening and lubrication and flexibility and to trap water and some humectants either from the aloe or from the conditioner to hold on to water.

      Other humectants could be protein if your hair tolerates it or panthenol (buy the powder in bulk) or making the mixture with marshmallow root-infused water. Glycerin will work too, but for some people it is too finicky an ingredient.

      If your hair only needs softening, then using oil is enough to soften and lubricate, but oil alone won't hydrate. Often if the hair only needs a little oil to soften and not a water-included rehydrating, it will just be dry or look fluffy in some places, but not consistently all over.

    2. Hi Wendy,
      Thanks for your suggestion and information. I don't use spray bottle, but apply water, conditioner and oil seperately instead (but it's the right dew point to try humectants too). How much does that differ from the spray bottle mix?

    3. Using a spray bottle is differs in speed of application! Some people like it, some don't. I think it's really convenient to have everything pre-mixed and ready to apply with just a quick spritz. I don't have extremely thick hair and that undoubtedly influences my preference.

    4. Ah I see. I have dense hair, so I think keep on doing a LOC-ish method suits better to me.

      I was also wondering: is it convenient to apply a penetrating oil (e.g. coconut oil) directly on dehydrated hair?
      Or is it in this case better to first re-hydrate my hair by applying water + conditioner and finally coat it with coconut oil?
      The purpose of coconut oil here is for example protection against humid / rain.

    5. Hi Sera,
      Oils are for softening, lubricating and adding flexibility as well as for sealing in moisture or buffering your hair from absorbing lots of water vapor from the air. I think if you apply coconut oil directly to dehydrated hair, that oil which can penetrate the hair has a better chance of doing so efficiently and the oil might have the best contact with the hair. The oil directly on the dry hair might give better lubrication and softening than diluted. My experience is that I get a really good result from applying oil to dry hair, followed by moistening and applying other water-based products over it. Better than mixing it with the other products, although sometimes mixing is more practical. So I guess I encourage you to try the oil on dehydrated or dry hair, followed by moistening with water + conditioner to rehydrate and observe your hair carefully - how it feels, how it behaves and see which layering order seems to work best.
      Oils as a final layer don't evaporate, but they tend to give that impression as they soak in (those that can) or disperse. "Heavier" oils that do not soak in like jojoba can be a good top layer.

  6. I have low porosity hair and would use baking soda or apple cider vinegar to cleanse and had swelling hair. After reading your article I now know this could damage your hair. I also use bentonite clay mixed with honey, olive oil, and warm water to cleanse and my hair LOVES this treatment. My regimene with this treatment is deep condition under a steamer first, use clay as cleanser, use water down conditioner as a leave in and seal with Camille rose almond jai twist butter. My question is is it ok to deep condition before I use the clay mix to cleanse? Or does it not matter if you do it before or after to hydrate and retain moisture. My ends are always hard to keep moisturized. Thank you for your time.

    1. Hello Desiree,

      If your hair is responding well to applying product in this order, that's great. What a great clay cleanser too! Usually it's recommended to use a deep conditioner after cleansing the hair so that there is no product residue (styling products, leave-ins) to block the conditioner from bonding directly with the "naked" hair. But that recommendation assumes you're using shampoo and thus removing excess oils whereas you are using oils and clay and honey to cleanse your hair.

      Clay cleansers can remove excess oils and I suspect that clay may remove some conditioner from the hair, or at least it has that potential based on its chemistry - all the negative charge that clay minerals bear on their surfaces *might* be able to grab the positively-charged conditioner molecules or otherwise pull some conditioner away.

      You might try reversing the order - clay cleanser first, then deep condition, rinse, apply leave in and seal. See if it gives you a different result - and one that you like.

      For hydration on your ends and moisture retention is sounds like your ends are a little more porous and may need more frequent application of a product that is moisturizing (aloe, marshmallow root, panthenol, slippery elm, etc.) to add some moisture as well as the oils that are in your sealing product to add flexibility and softness.
      I hope that helps!

  7. Hello, I tried to find an answer to my problem in your posts , but not sure what is the answer for myself.

    My hare look dull, lifeless and dry.
    Formular of shampoo I make:
    10% ALOE

    Conditioner for dry hair:
    7$ BTMS
    3% OLIVE OIL

    Thank you in advance.

    1. Hello Ekaterina, I have comments set to "moderate" to avoid having the comment section full of spam, so comments do not appear immediately after you type them.
      You are making your own shampoo and conditioner? The decyl glucoside I am familiar with is 50% active ingredients, so 25% should be mild. However, 5% wheat protein in a shampoo is a lot of protein for regular use. Every time you shampoo your hair, you are getting a quite strong protein "treatment." It might be better to reduce the protein to less than 3%. For that matter, when hair is acting dry and dull, and you've been using a lot of protein, you might want to avoid protein completely for a while and then add it back for occasional use - or at only 1-2%.
      If you are using an aloe powder instead of a liquid, 10% might be too strong. I can't comment about soy lecithin because I don't use that in shampoo.
      Triglycerides in shampoo can be good, but if your hair responds badly to coconut oil (see the next paragraph) then you don't want triglycerides in your shampoo because they might cause a similar problem. You could trade the triglycerides for an oil, or for Alkyl Benzoate.

      Your conditioner seems fine, the only ingredient that I can see which might cause a problem is coconut oil. For some people, coconut oil makes their hair dry or brittle or stiff. You might omit the coconut oil or exchange it for another oil to see if it makes a difference.
      Good luck - I'm interested to hear how you work this out.

  8. Hi. I have spent a few hours reading and re-reading your articles. I have a problem with stretchy strands. I have very thick, tightly coiled hair that is like you've described in several of your articles (resistant to water). I have used several popular protein treatments over the course of 3 months (protein treatment once every 3 weeks) but nothing is correcting the problem. I am growing very concerned that I may lose all my hair eventually if I can't get to the root cause. Can you shed some light on my problem. No pun intended. Thanks!

    1. Hello Teresa,
      Hair that stretches a lot and doesn't bounce back *when wet* is one indication that hair needs protein. But the stretch has to be gentle - a light, short tug specifically to see if it will bounce back. If you pull with increasing tension to see how far the hair will stretch before it breaks, you'll get a totally different impression.

      I think for hair that needs protein, as long as 1) your hair isn't quite coarse and 2) your protein isn't too concentrated, you need to use protein a bit more often to really get an impression of how it's working. In other words, increase the "dose."
      For low-porosity hair that isn't quite coarse, you might be able to use a protein-containing rinse-out conditioner on wash days if it has "smaller" proteins like keratin or silk or collagen. The "Phyto Keratin" like in Garnier Damage Eraser tends to be smaller proteins too - a blend of wheat, corn and soy that is hydrating and elasticity-promoting.

      You might have to back off on the protein later on, or if it doesn't change anything with an increased dose. But in the problem-solving stage, sometimes we have to "push" a treatment to see how far we can go and how much do we need to add to see a result.
      If you prefer to use more-concentrated treatments where protein is one of the first 5 or 6 ingredients (instead of protein in rinse-out conditioners) - you might use that every week until you see a change. If you go 3 weeks between protein and your hair really, really needed protein you might see some improvement for a few days, and then that benefit would be lost long before the next application.

      Follow up protein treatments with extra conditioner or a deep conditioning to make sure you balance out the support hair gets from protein with the softness and slip hair gets from the conditioner.

      By using more protein than you might aim to use in the longer term, you should be able to assess whether protein is going to bring some of that elasticity back to your hair. If you don't use enough, you won't know.

      You can adjust the intensity of effect of the protein by using heat or leaving it on longer (for a stronger treatment) or not using heat and leaving it on for less time (a milder treatment). Low porosity hair sometimes needs heat to coax out benefit from treatments of any sort.

      Popular treatments like Aphogee 2-step should give you a noticeable result after the first treatment. But if hair is damaged (sun, swimming, chemical processes, dry wind) - it may actually take a second treatment within a week or 2 to really see the breakage stop. That was me when my hair was long and sun/pool damaged. I used Aphogee 2-Step twice, about 4 or 5 days apart. Breakage ended right then and there.

      BUT... If your hair is not damaged and it *is coarse*, then protein may not be the answer to your problems at all and might make your hair want to break and feel dry and tangly or brittle. If you're not seeing any hint of improvement after using protein treatments, you may need to be using regular oil treatments with penetrating oils (coconut, sunflower, red palm, babassu, avocado) and making sure you have humectants in your leave-in products to help your hair stay hydrated.

      I hope that helps!

  9. If hydration means water inside the hair, then are we preventing hydration if there is oil inside the hair instead of water? I was confused on this part thanks!

    1. It sounds counter-intuitive, doesn't it? If you apply a penetrating oil to porous hair, the overall effect is slowing down the speed that water will move into the hair.
      With low-porosity hair, water moves in very slowly because the hair naturally repels water. In porous hair, too much water tends to move in too quickly, causing swelling inside the hair. But the cuticle layer can't swell - so there is stress inside the hair. Using a penetrating oil prevents that "too much water too fast" effect so porous hair isn't so stressed during washing.
      Water will still get inside the hair. I advocate light oil applications, not heavy oil applications for that reason, it's a layer of protection, not an impermeable raincoat.

  10. I noticed the picture of the cross-section of the hair is perfectly round. I know that African American hair-kinky hair in general tends to be more ovular than round. Mine especially- very oval-like. This plays a lot into elasticity and porocity, no?

    1. Hello Susana,
      Hair of people of Asian descent is round. Everybody else's is some variation of oval or elliptical. However, when I use my favorite graphic program to draw my visual aids, it doesn't draw ellipses very well. Neither do I.

      I should be using a different graphics program for that so I can represent hair correctly - I'm glad you brought that to my attention.

      Cross section or round vs. oval doesn't seem to have a whole lot to do with elasticity and porosity. Not as much as hydration and lubrication and hair-width do. For that matter, hair care probably has more to do with elasticity and porosity than any of those variables. There are other things that are difficult to describe. Some people's porous hair behaves more like low porosity hair. Some people's low-porosity hair soaks up hair products. Those things can have a lot to do with local water chemistry - like chlorine and minerals/hardness - and climate.
      Kinking hair can break more easily during handling, but if it is stretched with gentle and steadily increasing tension, it tends to be very close in elasticity to non-kinking hair. W

  11. Hi, I have spent countless hours pouring over hair forums and can use some sound advise on how to restore my once dense 2b hair. After moving to Southern CA I've lost about 1/3 of my hair due to breakage. I recently had a water filtration and conditioning system put into my home after reading that hard water could be to blame. On the other hand the air is also very dry. My hair is fine dries quickly and even after deep conditioning under a steam bonnet it is brittle and completely inelastic. It flots on water and will not sink leading me to believe it is low porosity but dries quickly,if product free, which makes me think high porosity. I do color my roots but just in select areas and somehow following that I do seem to get my elasticity back , It's as if damaging it forces moisture in. I need some way to get moisture in and keep it in so my hair isnt so bone dry and brittle. HELP

    1. Hello Jenni,

      Have you tried using protein at all? If your hair is on the finer side, protein could help with strength and elasticity (to reduce breakage). If it's somewhat porous due to coloring and hard water's dehydrating, stiffening effect protein can be helpful with hydration. A rinse-out conditioner with some protein used every wash day or every other wash day, or a protein reconstructor used every 1 or 2 weeks might help your hair feel better hydrated.
      With protein, use it as often as you get a good effect. If you stop getting a good effect - space out the use.

      Have you tried pre-wash oil treatments with penetrating oils? Those sometimes help when deep conditioning doesn't for flexibility. There's a post here (copy and paste link):

      Your observation about coloring your hair and how that makes it easier to use conditioners is spot-on. The damage that comes with coloring makes hair which is normally hydrophobic (water and conditioner-repellant) become hydrophilic (water and conditioner-attracting). Slightly damaged hair tends to be more agreeable with oils, conditioners and water. And this isn't even surprising when you consider that a lot of cosmetics research is done with dyed or bleached hair, or assumes that a significant percentage of the (female) population dyes, bleaches, or heat-styles their hair. Products are made with porous hair in mind.

      Check out my "Low Porosity" hair post - it has other tips for hydrating low porosity hair. It's linked in the "popular posts" at right. Good luck and best wishes! W