Chemist point of view- back to the basic and several questions

[Anabell]

Hey there!
I joined to LHC several years ago so I read a lot about hair care in the past few years. I also a chemist. I have a background both at chemistry and biology so I have general clue about hair structure and how hair products supposed to work.
Now, I've been thinking about several things I take for granted and also I want to ask the chemist in this forum:
Pre-poo treatment- whet exactly the purpose? I explain: basically we put some oil on dry hair before the wash. But if the hair is dry there no moisturize locked in within the process. The oil only acts like a barrier between the water in the air and the water inside the hair shaft. So I guess it just to prevent the shampoo wash the length? Isn't it will be better to spray some water on the hair before applying the oil to also lock in some moisture? So I tried it. The immediate result was weird. In the outside it feels really silky and smooth but the hair was locked in some kind of waves or locks and if I wanted just let my hand through the hair it was difficult. Now my hair is drying after wash so I will see the final results in a couple of hours.
So did anyone tried it? What was your result? What do you think about this method?
In generally speaking, what the advantages of just put oil in a dry hair? Does it gives something else other than a water barrier?

Another question that came to my mind: Humectants- how they work? Salts for example bad for hair because they absorb water both from the outside environment and from the hair itself. Humectants are considered good for hair because they draw water into the hair (for example aloe vera, honey). But how does it works? How it can draw water just in one direction from environment to the hair and don't take water from the hair itself?

[Nique1202]

I don't know about the pre-wash oiling, but I can say for humectants, it depends on how dry or humid the environment is. If you live in a very humid area, then humectants will (or are supposed to) draw moisture from the environment into your hair. If you live in a very dry area, humectants will (or should) draw moisture out of your hair. That's why it's always important to consider your climate when you decide whether to use products with humectants or not.

[pailin]

Nique is right about the humectants. And some of our members have commented on this- trying a new conditioner with aloe, for example, while on vacation, and loving it. Then going home to a dry climate and finding it terrible.
Regarding prewash oil, there is evidencethat coconut oil penetrates the hair shaft, so for it, prewash oiling is believed to help by reducing the amount of water taken up by the hairshaft during washing, and thereby reducing stress due to water, since water makes the hair swell. See this article: http://www.ncbi.nlm.nih.gov/pubmed
For most other oils, presumably preshampoo oiling does, as you say, merely reduce hair contact with shampoo.

ETA- regarding humectants, I'm not certain whose comments I'm remembering. Possibly Quasiquixotic.

[Anabell]

Thank you both for the informative responses. Totally forgot about the penetrating thing of coconut oil. So basically you can get two totally different treatment out of one product- a moisture treatment if you seal water in or a protein treatment (coconut oil has some protein in it) when use on dry hair. And of course we have this untrusting relationship of hair with water. At one hand hair can't do without some water and at the other hand too much water cause a hair shaft swallow and do some damage.
And humectants basically acts as a water gate and accelerate water transfer from high concentration to low concentration. This is confuse me because I know they are good (SMT treatment- some members here get very pleasant results with it) but I can't get how. Because what's the point using them when you have humid air anyway? You need the moisture in winter when you have dry air and so you hair and skin dry out. Anyway, just sharing my thoughts.

[lapushka]

Thank you both for the informative responses. Totally forgot about the penetrating thing of coconut oil. So basically you can get two totally different treatment out of one product- a moisture treatment if you seal water in or a protein treatment (coconut oil has some protein in it) when use on dry hair. And of course we have this untrusting relationship of hair with water. At one hand hair can't do without some water and at the other hand too much water cause a hair shaft swallow and do some damage.

Nope, coconut oil does *not* have protein. It keeps the protein in the hair, though.

[MsPharaohMoan]

Thank you Lapushka. Common misconception.

Pre poo treatments prevent hydral fatigue - hair swells with water and cuticles open. Doing this too often will cause cuticles to not be so efficient at closing (or something along those lines).

[hanne jensen]

Thank you Lapushka. Common misconception.

Pre poo treatments prevent hydral fatigue - hair swells with water and cuticles open. Doing this too often will cause cuticles to not be so efficient at closing (or something along those lines).

I didn't know this, thanks for that information. Can I use coconut oil as a pre poo treatment? I have around 200 grams of the stuff that needs to get used up.

[lapushka]

Can I use coconut oil as a pre poo treatment? I have around 200 grams of the stuff that needs to get used up.

I don't see why not. :) I wouldn't use too too much of it, though, just enough to coat your hair, otherwise you'll be washing it out twice (or even more depending on how much you used) and that kind of defeats the purpose.

[Entangled]

I don't see why not. :) I wouldn't use too too much of it, though, just enough to coat your hair, otherwise you'll be washing it out twice (or even more depending on how much you used) and that kind of defeats the purpose.
I use coconut oil as a pre-poo. I don't know how this works for other people, but I use a lot--I put it in until it's very stringy and looks wet, but it always comes out with just conditioner. I've never used shampoo to get it out. Conditioner works great to get out oil, but not sebum for me.

[Silverbrumby]

Thank you Lapushka. Common misconception.

Pre poo treatments prevent hydral fatigue - hair swells with water and cuticles open. Doing this too often will cause cuticles to not be so efficient at closing (or something along those lines).


Very interesting. My hair definitely swells with washing so pre oiling will I'm guessing reduce the swell shrink cycle of my hair there preserving the out cuticle which In parts shine and improves hair shaft strength.

Thinking out loud.

[AJNinami]

See this article: http://www.ncbi.nlm.nih.gov/pubmed

Does this link work for others?

Regarding coconut oil, doesn't it work similarly to a protein treatment?

[Arctic]

With humectants I have a theory that they work for many, even in drier air, because we humans have a micro climate around us. We perspirate and breath moisture around us all the time, so I assume this is what the humectants will help transfer back to us, to our hair to be exact. Also, conditioners are often used in shower, or steamy bathroom, which might help to "load" humectants and then they'll releace moisture to the hair (and probably also to the air). These are just my own theories and might be completely off.

Humectants aren't recommended in very humid climates, they can weight hair down and make curly/wavy hair frizzy. They are also not usually, at least when reading hair forums, recommended for very dry climates, so I assume they work best in avarage humidity. I personally have never had problems with them drying my hair out, I live where it can get pretty dry for a big part of the year, and my hair loves them.

[meteor]

Hey there!
I joined to LHC several years ago so I read a lot about hair care in the past few years. I also a chemist. I have a background both at chemistry and biology so I have general clue about hair structure and how hair products supposed to work.
Now, I've been thinking about several things I take for granted and also I want to ask the chemist in this forum:
Pre-poo treatment- whet exactly the purpose? I explain: basically we put some oil on dry hair before the wash. But if the hair is dry there no moisturize locked in within the process. The oil only acts like a barrier between the water in the air and the water inside the hair shaft. So I guess it just to prevent the shampoo wash the length? Isn't it will be better to spray some water on the hair before applying the oil to also lock in some moisture? So I tried it. The immediate result was weird. In the outside it feels really silky and smooth but the hair was locked in some kind of waves or locks and if I wanted just let my hand through the hair it was difficult. Now my hair is drying after wash so I will see the final results in a couple of hours.
So did anyone tried it? What was your result? What do you think about this method?
In generally speaking, what the advantages of just put oil in a dry hair? Does it gives something else other than a water barrier?

I think applying oil on wet hair can help lock in the water and slow down evaporation of water, since oil is occlusive. This is the mechanism that works in LOC/LCO or other methods of "sealing" moisture with oil.
Effect of oil films on moisture vapor absorption on human hair. - http://www.ncbi.nlm.nih.gov/pubmed/17520153

Calculated hysteresis plots show that the samples treated with different oils have slightly higher moisture retention at low relative humidities compared to that of the untreated sample, which suggests a beneficial effect. The calculated moisture diffusion coefficients for oil-treated samples were much lower compared to the untreated hair fibers, suggesting that surface oil films and penetrated oil molecules form a diffusion barrier. A moisture diffusion model is discussed in terms of the possible role of fiber swelling on restrictive narrowing of the cell membrane complexes (CMCs), which form the diffusion pathways in the fiber. The effect of film thickness on moisture absorption and the reverting of the sorption isotherm to that of the untreated hair after removal of the oil film shows that oil film is the main resistance to moisture diffusion. The lowering of the diffusion coefficient of water vapor by oil films will slow the loss of moisture, an effect similar to "moisturization" of hair.

Preliminary analysis of the distribution of water in human hair by small-angle neutron scattering. - http://www.ncbi.nlm.nih.gov/pubmed/24602821

This observation suggests that a significant fraction of water in the hair, which contributes to the CDS, is likely located in a different morphological region of hair that is more like pores in a fibrous structure, which leads to significant additional swelling of the fiber. Comparison of the scattering of hair treated with oil shows that soybean oil, which diffuses less into hair, allows more water into hair than coconut oil.


However, applying oil on dry hair would allow maximum amount of oil to penetrate the hair. I prefer to avoid doing pre-poo oiling on wet hair, since water would limit absorption of oil, as oil and water don't mix.

So it all depends on your goal for oiling whether to apply it on wet or dry. I think both can be pretty beneficial. :)

Overall, I'd break down the benefits of oils pre-wash and post-wash like this:
1) Pre-wash:
- reducing porosity temporarily,
- limiting exposure to harsh surfactants/minerals in the water,
- reducing hygral fatigue (from excessive swelling and de-swelling of hair fiber in water),
- reducing damage from wet abrasion associated with washing and wet manipulation.

2) Post-wash:
- occlusion - "sealing in" moisture from evaporating fast and penetrating fast (thus preventing frizz in humid conditions and excessive dryness in dry conditions),
- increasing elasticity,
- increasing slip, combability, and manageability (making detangling and styling easier),
- reducing hair porosity,
- providing a protective film (helps with reducing damage from mechanical, chemical damage, daily wear and tear...).


Since you are a chemist and would like some sources, I'd highly recommend the book "Chemical and Physical Behavior of Human Hair" by Clarence R. Robbins and a couple of relevant studies specifically on coconut oil and its prevention of damage (measured by protein loss) from washing and grooming, e.g.:
Effect of coconut oil on prevention of hair damage: http://journal.scconline.org/pdf/cc1999/cc050n06/p00327-p00339.pdf (coconut oil left in hair for 48 hours pre-wash, shows effects on virgin, bleached and boiled hair... on straight, wavy, curly hair)
Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage: http://journal.scconline.org/pdf/cc2003/cc054n02/p00175-p00192.pdf (coconut oil left in hair for 14 hours, to simulate overnight application)

Here is another good study: Investigation of penetration abilities of various oils into human hair fibers. - http://www.ncbi.nlm.nih.gov/pubmed/16258695, which demonstrated that "with coconut, olive, and sunflower oils the capillary adhesion was found to decrease with time, but not with mineral oil", possibly because "the reduction in capillary adhesion between hair fibers is most likely due to thinning of oil films by absorption of oil into the hair", so it's possible that some oils, other than the well-studied coconut oil, can penetrate hair, as well.




See this article: http://www.ncbi.nlm.nih.gov/pubmed
Does this link work for others?

Regarding coconut oil, doesn't it work similarly to a protein treatment?

The link didn't work for me either.
Oil and protein treatments are different, since uncontaminated coconut oil (or any oil, for that matter) contains 100% fat and 0% protein.
Protein treatments are supposed to deposit hydrolyzed (i.e. broken up into smaller pieces) proteins on top of hair, creating a protective film, and if they are small enough, they can penetrate hair. Oils can sit on top of hair creating an occlusive barrier and sometimes penetrate under the cuticle, as well (if the molecular size is small enough, e.g. coconut oil, or if the cuticles are chipped enough and the hair is porous, etc...). This sounds similar enough, but oils are occlusives while hydrolyzed proteins can even work like humectants (http://science-yhairblog.blogspot.ca/2014/07/film-forming-humectants-what-they-are.html, http://swiftcraftymonkey.blogspot.ca/2010/06/conditioners-using-hydrolyzed-proteins.html)
I think the more porous, damaged the hair is, the more beneficial oils and proteins can be for it, since they help manage high porosity by forming protective films and temporarily patch-repairing chipped cuticle.


Very interesting. My hair definitely swells with washing so pre oiling will I'm guessing reduce the swell shrink cycle of my hair there preserving the out cuticle which In parts shine and improves hair shaft strength.

Thinking out loud.

Yes, that's right! :agree: There are a few studies out there that support it.
Coconut oil has been shown to penetrate hair and bind to hair's protein, preventing some damage (protein loss) during washing (studies # 1, 2, and 3).
According to study # 3:
This study also indicates that the swelling of hair is limited by the presence oil. Since the process of swelling and deswelling of hair is one of the causes of hair damage by hygral fatigue, coconut oil, which is a better penetrant than mineral oil, may provide better protection from damage by hygral fatigue.
Another study (# 4) shows that hair can absorb around 15% of its weight in coconut oil in an hour. An overnight soaking oil increases absorption to around 20% or 25%. This is good news, because it lowers the risk of hygral fatigue (damage from swelling and de-swelling of hair shaft from water, like an old elastic tape) from overwashing hair.

See the studies:
(1) Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage: http://www.ncbi.nlm.nih.gov/pubmed/12715094
(2) Investigation of penetration abilities of various oils into human hair fibers: http://www.ncbi.nlm.nih.gov/pubmed/16258695
(3) Secondary ion mass spectrometric investigation of penetration of coconut and mineral oils into human hair fibers: relevance to hair damage: http://www.ncbi.nlm.nih.gov/pubmed/11413497
(4) Quantitative measurement of the penetration of coconut oil into human hair using radio-labeled coconut oil: http://www.ncbi.nlm.nih.gov/pubmed/22487449

[AJNinami]

Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage: http://journal.scconline.org/pdf/cc2003/cc054n02/p00175-p00192.pdf (coconut oil left in hair for 14 hours, to simulate overnight application)

Interesting. I'm still reading through the studies and I'm not sure I fully understand them, but according to this one (I think) using coconut oil before going out into the sun can dramatically reduce sun damage? I've been looking for ways to do that. Thank you :)

What if you were to oil both pre wash and post wash? What would be the effect of using a humectant after that?

[meteor]

Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage: http://journal.scconline.org/pdf/cc2003/cc054n02/p00175-p00192.pdf (coconut oil left in hair for 14 hours, to simulate overnight application)
Interesting. I'm still reading through the studies and I'm not sure I fully understand them, but according to this one (I think) using coconut oil before going out into the sun can dramatically reduce sun damage? I've been looking for ways to do that. Thank you :)

What if you were to oil both pre wash and post wash? What would be the effect of using a humectant after that?

Yes, protection from UV rays is a big reason why I love using coconut oil in summertime (another reason being protection from saltwater and chlorinated pool water...).

There is a great graph on page 181 of the study I linked (http://journal.scconline.org/pdf/cc2003/cc054n02/p00175-p00192.pdf) that shows protein loss from UV damage with and without oils - and coconut oil outperforms sunflower oil *dramatically* there, both pre-wash and post-wash. That whole study was testing both pre-wash and post-wash applications of oil, and it does appear that using coconut oil both pre-wash and post-wash provided the best results.

I don't know how exactly this would affect humectants applied after the oils, since I haven't seen any studies combining the two, but I would imagine that it shouldn't block it much, since oils create only a light *permeable* occlusive barrier (not to mention how hard it is to *really* coat hair thoroughly).
You can still layer products like creams and gels in LOC/G, for example. Honestly, my favorite moisturizing treatments (e.g. oil + honey masks, SMT + oil, gelatin mask + oil + honey, HALO rinse, etc) and many leave-in moisturizers happily combine humectants and oils high up on the ingredients lists, and I don't see a problem there. :)

[meteor]

Oh, AJNinami, I forgot to add more on the sequence (from page 189 of http://journal.scconline.org/pdf/cc2003/cc054n02/p00175-p00192.pdf):


The data in Figures 6-9 show that the sequence of application (whether pre- or postwash) is important. Post-wash application is less effective in reducing the WRI as compared to pre-wash application. The difference seems to be in the location of the oil residues and their ability to counteract surfactant damage. In post-wash application the oil film is on the surface, with no penetration into the fiber. In pre-wash application, it is possible that the molecules of the oil penetrate into the cuticle and probably even into the cortex. This may also be the case with undamaged hair, although the effect is small. The reduction in the WRI must be due to the introduction of the hydrophobic triglyceride into the keratin structure.
WRI = % Water Retention Index (another measurement they used, apart from protein loss to measure damage)

And as I mentioned earlier, ideally, you get best results from combining both pre- and post-wash applications, according to the tests done in this study. HTH! :flower:

[AJNinami]

HTH! :flower:

Thank you so much! this was very helpful to me :)

[AJNinami]

Double Post :blossom:

[meteor]

^ Any time, AJNinami! :D
I'm a big fan of oils and all sorts of oiling methods (especially on ends, where more damage normally accumulates). :D

[pailin]

Does this link work for others?

Regarding coconut oil, doesn't it work similarly to a protein treatment?

Sorry about that, I must not have copied the entire link.
But meteor linked it in her post. I'm glad to see she came along, because she always lots of information on the science of haircare.

[meteor]

^ You are too kind, pailin! :oops: Thanks so much! :flowers:

By the way, there is probably more research out there on oils and hair that I'm just not aware of, but I love to learn, so if somebody has more links to share, please post away! :)
I also wish that coconut oil could be finally tested pre-bleach (there are lots of folks who use it as a buffer for bleach/dye and it seems to work beautifully, so anecdotal evidence is pretty abundant, but it would be nice to have some research into this), and I wish all sorts of natural oils were researched in terms of their effect on hair, since many people prefer other oils to coconut oil and it would be so great to know what exactly drives that (hmm, maybe texture or individual strand thickness or something...?) :)

[Anabell]

Regarding prewash oil, there is evidencethat coconut oil penetrates the hair shaft, so for it, prewash oiling is believed to help by reducing the amount of water taken up by the hairshaft during washing, and thereby reducing stress due to water, since water makes the hair swell. See this article: http://www.ncbi.nlm.nih.gov/pubmed
For most other oils, presumably preshampoo oiling does, as you say, merely reduce hair contact with shampoo.


Pallin, I can't see the link either. It leads to the home page of pubmeds.

Some how I was stuck in my head that coconut oil contain proteins. I assume I confused it with coconut milk? :confused:

Meteor thank you for all the useful and interesting information *go to read*.
First insights- so by the first reference- it seems like oils composed from more saturated fats will penetrate easily to the hair shaft while the unsaturated ones will produces a film outside. So generally speaking if this theory is right the heavier the oil the more it penetrate into the hair shaft. Maybe thats why they considered heavy in the first place? :hmm:
I see from the first study that oiled hair does retain some water anyway (which is good) but this is probably during the washing process. What concern me is to completely dry out the hair in the pre-treatment. I mean, hair needs some amount of water...

[meteor]

Meteor thank you for all the useful and interesting information *go to read*.
First insights- so by the first reference- it seems like oils composed from more saturated fats will penetrate easily to the hair shaft while the unsaturated ones will produces a film outside. So generally speaking if this theory is right the heavier the oil the more it penetrate into the hair shaft. Maybe thats why they considered heavy in the first place? :hmm:

Thank you, Anabell! :D Yes, I think you are onto something... Their hypothesis was that the differences could be due to the differences in the oils' respective fatty acid compositions and molecular sizes that cause some oils to just sit on top of hair.

Both sunflower and mineral oils do not help at all in reducing the protein loss from hair. This difference in results could arise from the composition of each of these oils. Coconut oil, being a triglyceride of lauric acid (principal fatty acid), has a high affinity for hair proteins and, because of its low molecular weight and straight linear chain, is able to penetrate inside the hair shaft. Mineral oil, being a hydrocarbon, has no affinity for proteins and therefore is not able to penetrate and yield better results. In the case of sunflower oil, although it is a triglyceride of linoleic acid, because of its bulky structure due to the presence of double bonds, it does not penetrate the fiber, consequently resulting in no favorable impact on protein loss. Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage: http://www.ncbi.nlm.nih.gov/pubmed/12715094

As for the idea of "heaviness" and "lightness" of oil, I think it can be kind of tricky... I think some people talk about viscosity when they call an oil "heavy", e.g. a "thick" oil like castor oil. It may not necessarily translate directly to hair's ability to absorb it... I don't know...


I see from the first study that oiled hair does retain some water anyway (which is good) but this is probably during the washing process. What concern me is to completely dry out the hair in the pre-treatment. I mean, hair needs some amount of water...

I don't think an oil can completely dry out the hair. After all, you can easily get hair wet when it's oiled, even heavily oiled, because that barrier is permeable. I think the "dryness" is more about the feeling of build-up from using way too much oil. If the hair is very dry when you want to use oil pre-wash, it certainly makes sense to spray it with some water, but if not, it's not necessary IMHO.

Oh, and by the way, since you mentioned wanting to retain water, in that study, the % Water Retention Index (%WRI) refers to the swelling propensity of hair in water as a measurement of damage (more damaged hair is assumed to absorb more water), so retention of water is actually seen as a negative thing, to be reduced where possible, just like protein loss. Since repeated swelling and contraction damages the cuticle, reduction in the WRI can be considered as beneficial in reducing hair damage. [...] The reduction in the WRI must be due to the introduction of the hydrophobic triglyceride into the keratin structure." (http://journal.scconline.org/pdf/cc2003/cc054n02/p00175-p00192.pdf, pp. 188 - 189)
WRI = (Weight wet - Weight dry) 100 / Weight dry (the details on how it's measured during experiments are in pp. 181 - 182)

Hair already contains water and moisturized hair is not about being wet (since water easily evaporates), it's more about hair's ability to maintain adequate hydration in different environments - usually by keeping cuticle intact, not too porous, and with judicious use of humectants (to attract and help hold onto water) and occlusives (to slow down evaporation of water).

Also, keratin temporarily changes when hair is wet, and the structure is more fragile, and CMC (cell membrane complex) inside hair bulges when hair is left to stay wet for a long period of time while air-drying (which isn't seen with blow-drying on cool/warm setting):
Hair Shaft Damage from Heat and Drying Time of Hair Dryer - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3229938/

The CMC was damaged only in the naturally dried group. This result was quite unexpected, because increased temperatures generally led to more hair damage. It took over 2 h to dry the hair tress completely under ambient conditions. The hair shaft swells when in contact with water, as does the delta-layer of the CMC. The delta-layer is the sole route through which water diffuses into hair, and so we speculate that the CMC could be damaged when it is in contact with water for prolonged periods. Longer contact with water might be more harmful to the CMC compared to temperature of hair drying.

Hair in good condition can absorb more than 30% of its own weight of water, for damaged hair, this percentage can reach 45% (or even more). (I think this might be related to what people sometimes notice when the hair feels mushy, gummy when it's wet, if it's over-bleached or over-relaxed or otherwise very compromised, for example.)
You can read on this and other interesting stuff about the relationship between water and hair here: http://www.hair-science.com/_int/_en/topic/topic_sousrub.aspx?tc=root-hair-science%5Eso-sturdy-so-fragile%5Eproperties-of-hair&cur=properties-of-hair

[hanne jensen]

Thanks, lapushka and Entangled. Will grease my hair down next wash. I've heavily greased my hair before with coconut oil and it washed right out.

[Anabell]

Meteor, by heavy oils I mean heavy on hair. The ones you easily overdone. It is very easy to know how much oil is saturated- the higher boiling (or melting) point the more saturated fatty acids will compose the oil. And you are right, viscosity its a whole different parameter that might effect the penetration as well.

Hmm... very interesting. Especially the study about the hair drying. It might be true but they didn't took into account tables that might created in very long hair as a result of using hair dryer. I guess it is possible to just use it in low temp mode (the in-between option that is war, but not hot). It is surprise me that water is bad for hair. At least in big amounts for long periods of time. Hair is so nice and soft when it moisturised.

Another question that came to my mind- what is build up, chemically speaking? Is there any studies about this? I know oils can oxidise so it might be related. Because the main issue with coconut oil that it sometimes create build up. An I have the feeling that this is a feature of thick saturated oils.

[meteor]

^ Oh yes. :) That hair-drying study showed dryness as well as damage from blow-drying (and the higher the heat, the more damaged the hair became), but on cuticle level. Hair staying water-logged for a while due to air-drying resulted in cell-membrane-complex bulging. The researchers were surprised by that, and I think we'd need more studies to figure out what happened on the CMC level. Basically, for now, it seems like the safest drying process is both heat-free and fast, so something like air-drying outside or in a a warm room close to a fan maybe?

As for build-up, I haven't seen studies on that, sorry.
I think of build-up as just a coating that makes hair harder to detangle, less manageable, maybe less soft and shiny or more crunchy/brittle or more lank and greasy - just a coating to be removed with effective clarifying. Build-up can sometimes be hard to measure and figure out in advance without trial and error, since our porosities are different, we all have different types and amounts of hair that can be in need of different ingredients... Generally speaking, I think the more damaged, porous the hair is, the more stuff it can absorb before showing any signs of build-up. But virgin, fine hair is probably easier to overwhelm. Almost anything has potential to build up, so it's important to remember what works and in what amounts for your own hair, since it's very YMMV. :flower:
As for coconut oil, it can build up, like any other oil, and it has a further complication of solidifying at temperatures below 24 C. For example, I find it easily makes my hair crunchy if I use it in cold weather or use too much and don't spread it out thoroughly. Fractionated coconut oil might be easier to work with.

[Silverbrumby]

This is so helpful. Thank you meteor.

I wash hair and bun it rather wet and go to bed. Then in the morning it's still damp and I let it air dry then. Maybe that's why I have bumpy hair strands? I'll stop that practice now going forward and see if it helps.

Love this thread. Thanks everyone for contributing.




Oh, and by the way, since you mentioned wanting to retain water, in that study, the % Water Retention Index (%WRI) refers to the swelling propensity of hair in water as a measurement of damage (more damaged hair is assumed to absorb more water), so retention of water is actually seen as a negative thing, to be reduced where possible, just like protein loss. Since repeated swelling and contraction damages the cuticle, reduction in the WRI can be considered as beneficial in reducing hair damage. [...] The reduction in the WRI must be due to the introduction of the hydrophobic triglyceride into the keratin structure." (http://journal.scconline.org/pdf/cc2003/cc054n02/p00175-p00192.pdf, pp. 188 - 189)
WRI = (Weight wet - Weight dry) 100 / Weight dry (the details on how it's measured during experiments are in pp. 181 - 182)

Hair already contains water and moisturized hair is not about being wet (since water easily evaporates), it's more about hair's ability to maintain adequate hydration in different environments - usually by keeping cuticle intact, not too porous, and with judicious use of humectants (to attract and help hold onto water) and occlusives (to slow down evaporation of water).

Also, keratin temporarily changes when hair is wet, and the structure is more fragile, and CMC (cell membrane complex) inside hair bulges when hair is left to stay wet for a long period of time while air-drying (which isn't seen with blow-drying on cool/warm setting):
Hair Shaft Damage from Heat and Drying Time of Hair Dryer - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3229938/


Hair in good condition can absorb more than 30% of its own weight of water, for damaged hair, this percentage can reach 45% (or even more). (I think this might be related to what people sometimes notice when the hair feels mushy, gummy when it's wet, if it's over-bleached or over-relaxed or otherwise very compromised, for example.)
You can read on this and other interesting stuff about the relationship between water and hair here: http://www.hair-science.com/_int/_en/topic/topic_sousrub.aspx?tc=root-hair-science%5Eso-sturdy-so-fragile%5Eproperties-of-hair&cur=properties-of-hair

[Pol]

What a fascinating thread, thank you everyone! I certainly feel the benefit from both pre and post poo oiling, so it's good to know there is evidence to support this! As a regular washer I am reading the water damage info with interest, I might try speeding up my drying time with some (heat free) hairdrying and see if I notice any change. Experimentation is fun! Also, Meteor, you have a gift for explaining complicated things simply - thank you!

[meteor]

^ Thank you so very much, Pol and Silverbrumby! :flowers:
Silverbrumby, I damp-bun as well :) , just out of necessity (it takes too many hours to air-dry loose and life has to go on ;) ), but I don't worry about it much, since I don't wash hair that frequently. If I washed hair very frequently and wore it in wet buns every day or something like that, I'd be very particular about wearing only very low-manipulation, loose styles for wet-bunning (LWB, for example) ... just because hair is fragile when wet (a bit more on lower tensile strength of wet, relative to dry, hair: http://journal.scconline.org/pdf/cc1978/cc029n08/p00449-p00467.pdf) and it can shrink up quite a bit as it's letting go of water, so I think it's safer not to do any wet-bun styles that stretch hair too much. Also, when I have opportunity, I take down the damp bun, even if just for a short time here and there - it helps speed up the process a bit, until I have time to completely air-dry it loose. :)
Also, wet-bunning with 2 or more buns (instead of 1 bun) can help it dry a bit faster, too, since hair is more spread out. And half-ups can speed up the drying process quite a bit.

[Silverbrumby]

^ Thank you so very much, Pol and Silverbrumby! :flowers:
Silverbrumby, I damp-bun as well :) , just out of necessity (it takes too many hours to air-dry loose and life has to go on ;) ), but I don't worry about it much, since I don't wash hair that frequently. If I washed hair very frequently and wore it in wet buns every day or something like that, I'd be very particular about wearing only very low-manipulation, loose styles for wet-bunning (LWB, for example) ... just because hair is fragile when wet (a bit more on lower tensile strength of wet, relative to dry, hair: http://journal.scconline.org/pdf/cc1978/cc029n08/p00449-p00467.pdf) and it can shrink up quite a bit as it's letting go of water, so I think it's safer not to do any wet-bun styles that stretch hair too much. Also, when I have opportunity, I take down the damp bun, even if just for a short time here and there - it helps speed up the process a bit, until I have time to completely air-dry it loose. :)
Also, wet-bunning with 2 or more buns (instead of 1 bun) can help it dry a bit faster, too, since hair is more spread out. And half-ups can speed up the drying process quite a bit.

Thanks Meteor. I wash my hair twice a week (scalp gets hot and funky otherwise). Hmm. My hair doesn't take that long to hair dry at BSL and sharp thickness drop off at armpit. I will not hard tight bun it and will wait till it's less wet before bunning. I think the oiling pre-wash definitely made it feel better today. I use argan oil as coconut oil leads to my hair feeling awful. My husband said my hair is looking better and better since being on LHC. Woot!

[meteor]

^ Yay, that sounds great, Silverbrumby! :thumbsup: Congrats on such fast improvement! :D

[Anabell]

^ Oh yes. :) That hair-drying study showed dryness as well as damage from blow-drying (and the higher the heat, the more damaged the hair became), but on cuticle level. Hair staying water-logged for a while due to air-drying resulted in cell-membrane-complex bulging. The researchers were surprised by that, and I think we'd need more studies to figure out what happened on the CMC level. Basically, for now, it seems like the safest drying process is both heat-free and fast, so something like air-drying outside or in a a warm room close to a fan maybe?


I guess the best way is to leave the hair in the towel/t-shirt the minimum time it needs to not dripping water on the floor. Then put some oil on the ends and gently separate the hair to smaller sections. I found this method the most effective for quick air dry. All that assuming the separation doesn't add any more damage. But I think it is much easier over done with hair dryer (in real life you won't measure exact distance and temperature of hair dryer and you wouldn't seat still like the hair samples) and the cool setting take ages to do something. Another option is to use hair dryer through the towel/t-shirt assuming that will protect the hair from over heating. But that is too much to bother in my opinion. Hair supposed to be fun. So I just would separate it (which i will need to do anyway for detangle) and go.