Hair Science Thread

[meteor]

Hair science lovers unite!
Let's start a thread for sharing and discussing hair research and all the relevant hair/scalp questions.


There is lots of great science-based hair information out there, but it's easily dispersed and sometimes hard to find. This thread is for bringing it all together, discussing old and new studies, findings, their limitations, and questions raised!


If you come across any interesting hair/scalp-related studies, please share them here!
And if you have any hair-science-related questions, please ask away!
Also, feel free to share any hair experiments or maybe hair photographs through microscope that you've taken, any concerns you may have about current studies or questioning "common knowledge" or hair "myths"... – pretty much anything that can help us understand hair better!


No need to be a chemist or a trichologist, of course! (And I'm not one either, sorry )This thread is for sharing and discussing information freely, so general curiosity is more than enough to join and share!


Special Big thanks to Arctic for her wonderful ideas for this thread!!

[meteor]

INDEX - PART 1

Hair Basics and Relevant Studies:

1. Hair Damage:

1.1 Photo-damage (UV damage): (post # 5 - studies) UVB: morphological damage, protein loss; UVA: biochemical damage, color changes

1.2 Chemical damage:

• Bleaching: (post # 127 - studies Part I)

• Dyeing: (post # 127 - studies Part I)

• Perming and Relaxing: (post # 128 - studies Part II)

• Keratin Straightening (Brazilian, Japanese straightening): (post # 128 - studies Part II)

1.3 Mechanical damage: (post # 166 - studies Part I, post # 167 - studies Part II)

1.4 Thermal / heat damage: Blow-drying and direct heat (post # 92 - studies)


2. Hair Structure: (Studies on overall structure, keratin, 18-MEA, ceramides, etc: post # 130), (Studies on CMC and cuticle: post # 153)


3. Sebum and Hair Oils:

3.1 Sebum Composition: (post # 36 - natural and artificial sebum)
http://www.dermnetnz.org/acne/sebum.html

Sebum and acne: (post # 77)

3.2 Details on intercellular lipids: (post # 130)

Hair Pigmentation:

- The cell biology of human hair follicle pigmentation: http://www.ncbi.nlm.nih.gov/pubmed/21070612

- Aging of the Hair Follicle Pigmentation System: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2938584/

- Graying: gerontobiology of the hair follicle pigmentary unit: http://www.ncbi.nlm.nih.gov/pubmed/11162910

- Hair cycle and hair pigmentation: dynamic interactions and changes associated with aging: http://www.ncbi.nlm.nih.gov/pubmed/15036274

- Hair Follicle Pigmentation: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1201498/


4. Hair Growth:

Downloadable Excel Table for Managing Your Hair Growth Data: http://forums.longhaircommunity.com/...ad.php?t=36275


- Melanogenesis during the anagen-catagen-telogen transformation of the murine hair cycle: http://ac.els-cdn.com/S0022202X94946...71f70570611601

- Peppermint Oil Promotes Hair Growth without Toxic Signs: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4289931/

- Action Mechanism of Chamaecyparis obtusa Oil on Hair Growth: http://www.ncbi.nlm.nih.gov/pubmed/24578794

- The essential oils of Chamaecyparis obtusa promote hair growth through the induction of vascular endothelial growth factor gene: http://www.ncbi.nlm.nih.gov/pubmed/19576968

- Effectiveness of the combinational treatment of Laminaria japonica and Cistanche tubulosa extracts in hair growth: http://www.ncbi.nlm.nih.gov/pubmed/25806080

- Hair growth-promoting effect of Carthamus tinctorius floret extract: http://www.ncbi.nlm.nih.gov/pubmed/24338940

- The hair growth promoting effect of Asiasari radix extract and its molecular regulation: http://www.ncbi.nlm.nih.gov/pubmed/15862941

- The hair growth promoting effect of Sophora flavescens extract and its molecular regulation: http://www.ncbi.nlm.nih.gov/pubmed/12354419

- Relationships between hair growth rate and morphological parameters of human straight hair: a same law above ethnical origins? http://www.ncbi.nlm.nih.gov/pubmed/21951315 (Discussion: post # 154)

- Changes in Chinese hair growth along a full year: http://www.ncbi.nlm.nih.gov/pubmed/25065943 (Discussion: post # 165)


5. Hair Thickness/Density:
"120,000 to 150,000 - the number of individual hairs in a full head of hair.
250 - the number of hairs per square centimetre of scalp. This figure varies between 200 and 300 according to the area of scalp in question."(L'Oreal Hair Science)

LHC stats on correlations between strand thickness, ponytail circumference and length: (post # 144)

How to calculate your density from strand thickness and ponytail circumference: (post # 183 and 3rd (last) point in "Terminal Length Calculations" Tab on spreadsheet here: http://forums.longhaircommunity.com/...ad.php?t=36275)


6. Hair Strand Thickness (Fineness – Coarseness): 17 - 181 microns Diameter of a Human Hair: http://hypertextbook.com/facts/1999/BrianLey.shtml or 58 - 100 microns (L'Oreal Hair Science)
< 40 microns - very fine
40 - 60 microns - fine
60 - 80 microns - medium
> 80 microns - coarse (80 - 95 - slightly coarse, 95 - 110 - moderately coarse, > 110 - very coarse)
(http://science-yhairblog.blogspot.co...oarse-how.html)

Hair strand thickness and age: (post # 124)

A method for measuring hair strand thickness: http://forums.longhaircommunity.com/...d.php?t=136858


7. Hair Porosity:
Damaged hair can absorb 45% of its weight in water; undamaged hair in good condition can absorb 30% (L'Oreal Hair Science)

- True porosity measurement of hair: a new way to study hair damage mechanisms: http://www.ncbi.nlm.nih.gov/pubmed/18818850

On the importance of oiling high-porosity hair:

- The effects of lipid penetration and removal from subsurface microcavities and cracks at the human cuticle sheath: http://www.ncbi.nlm.nih.gov/pubmed/19450411
"The presence of exogenous lipids in these cavities was found to be critical in maintaining the mechanical integrity of the cuticle cells."

- Managing elasticity and porosity in hair (blog): http://science-yhairblog.blogspot.ca...y-in-hair.html


8. Hair Texture: (post # 132 - studies)


9. Pictures - Hair and Scalp under Microscope: (post # 69, post # 70)


10. Hair Loss (Alopecia):

10.1. Androgenetic Alopecia: Studies on Androgenetic Alopecia: (Part I: post # 118 , Part II: post # 119)
(post # 76 - studies on AGA and Ketoconazole, DHT and oiliness connection discussed)
(post # 103 - summary of study on 1% ketoconazole, 1% piroctone olamine and 1% zinc pyrithione for hair loss, post # 104)

10.2. Alopecia Areata: (post # 45 - studies on Alopecia Areata)

[meteor]

INDEX - PART 2

I. Hair Care Ingredients:

Surfactants:

- Surfactant structure effects on swelling of isolated human stratum corneum:
http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf

Oils:

- Penetrating oils: post # 14, post # 25, oil rinses - post # 34, pre-wash (blog) - http://science-yhairblog.blogspot.co...-pre-wash.html)
(post # 170 - Brazilian oils and butters for gloss, split ends, combability, strength; coconut oil absorption rates),
(post # 172 - Argan oil and Cupuassu butter reduce protein loss after hair dye)

- Anti-bacterial and anti-fungal oils: (post # 57 - studies 1, post # 58 - studies 2)

- Drying capacity of oils: (post # 173)


Silicones:

- Nanotribological effects of silicone type, silicone deposition level, and surfactant type on human hair using atomic force microscopy: http://www.ncbi.nlm.nih.gov/pubmed/16676122

Silicone Solubility List: http://science-yhairblog.blogspot.co...lity-list.html


Hydrolyzed Proteins:

- http://science-yhairblog.blogspot.ca...lthy-hair.html "The protein polymer, hydrolyzed wheat protein polysiloxane copolymer was found to prevent cuticle cracking. Other proteins and conditioners were not tested. Other testing has demonstrated that P/DMAPA Acrylates Copolymer and Polyquaternium-55 have good heat-protecting qualities."

Amino Acids:
- Hair and amino acids: the interactions and the effects: http://www.ncbi.nlm.nih.gov/pubmed/17728935

Basics on hydrolyzed proteins: http://science-yhairblog.blogspot.co...formation.html and http://science-yhairblog.blogspot.co...t-protein.html

Protein size - http://www.thenaturalhavenbloom.com/...ning-part.html)


Humectants:

Film-forming humectants: (blog) http://science-yhairblog.blogspot.co...-they-are.html

Glycerin

Honey


Polymers:

- Conditioning polymers in today's shampoo formulations - efficacy, mechanism and test methods: http://www.ncbi.nlm.nih.gov/pubmed/18503458

- Quantitative methods for evaluating optical and frictional properties of cationic polymers: http://www.ncbi.nlm.nih.gov/pubmed/11382843

- Surfactants, polymers and their nanoparticles for personal care applications: http://www.ncbi.nlm.nih.gov/pubmed/15645085

- Polymer/surfactant interactions and nanostructures: current development for cleansing, release, and deposition of actives: http://www.ncbi.nlm.nih.gov/pubmed/21635852

- Effects of low-level hydrophobic substitution on conditioning properties of cationic cellulosic polymers in shampoo systems: http://www.ncbi.nlm.nih.gov/pubmed/15645097

- Evaluation of novel synthetic conditioning polymers for shampoos: http://www.ncbi.nlm.nih.gov/pubmed/19450423

- New high-charge density hydrophobically modified cationic HEC polymers for improved co-deposition of benefit agents and serious conditioning for problem hair: http://www.ncbi.nlm.nih.gov/pubmed/17728943


Basic Hair Care Practices and Products:

- Hair: its structure and response to cosmetic preparations: http://www.ncbi.nlm.nih.gov/pubmed/8901408

- The biology of hair care: http://www.ncbi.nlm.nih.gov/pubmed/11059373

- Biology of human hair: know your hair to control it: http://www.ncbi.nlm.nih.gov/pubmed/21072698

- Hair cosmetics: http://www.ncbi.nlm.nih.gov/pubmed/2022094

- Hair shaft effects from cosmetics and styling: http://www.ncbi.nlm.nih.gov/pubmed/10439246


Cleansing Methods:

Microscope photography and comparison of hair strands washed with:

- Conditioner (Co-Wash) vs. Shampoo vs. Water Only vs. Unwashed Hair : http://www.thenaturalhavenbloom.com/...your-hair.html

- Bentonite Clay vs. Rassoul Clay vs. Shampoo vs. Unwashed Hair: http://www.thenaturalhavenbloom.com/...hair-with.html

- Baking Soda vs. ACV vs. Shampoo vs. Unwashed Hair: http://www.thenaturalhavenbloom.com/...king-soda.html

- Shikakai vs. Bentonite Clay vs. Baking Soda vs. ACV vs. Shampoo vs. Conditioner (CO-Wash) vs. Water Only vs. Unwashed Hair: http://www.thenaturalhavenbloom.com/...-shikakai.html

- Compilation: Oat Water vs. Bentonite Clay vs. Rassoul Clay vs. Baking Soda vs. ACV vs. Shampoo Bar vs. Castile Soap vs. Shampoo vs. Conditioner (CO-Wash) vs. Unwashed Hair: http://www.thenaturalhavenbloom.com/...cleansers.html

- Matting of scalp hair during shampooing--a new look: http://www.ncbi.nlm.nih.gov/pubmed/2347105

- Matting of hair: what is the role of conditioners? http://www.ncbi.nlm.nih.gov/pubmed/16503900

Sodium Lauryl Sulfate vs. Sodium Coco Sulfate: (post # 115)


Water Hardness, Mineral Build-Up, Chelating: (post # 180, post # 181)


Conventional Products:

Hair Cosmetics: An Overview: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4387693/

Shampoos - Studies:

- Selective removal of sebum components from hair by surfactants: http://journal.scconline.org/pdf/cc1...309-p00320.pdf

- Shampoos: ingredients, efficacy and adverse effects: http://www.ncbi.nlm.nih.gov/pubmed/17451380

- Shampoos: composition and clinical applications: http://www.ncbi.nlm.nih.gov/pubmed/9914886

- The cross-modal effect of fragrance in shampoo: Modifying the perceived feel of both product and hair during and after washing: https://www.researchgate.net/publica..._after_washing


Anti-dandruff Shampoos: (post # 134 - studies)


pH - Studies: Evaluation of pH of Bathing Soaps and Shampoos for Skin and Hair Care: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4171909/; The Shampoo pH can Affect the Hair: Myth or Reality? : http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4158629/
pH and hair (blog): http://science-yhairblog.blogspot.co...x-to-make.html

2-in-1 Products:

- 2-in-1 shampoo technology: state-of-the-art shampoo and conditioner in one: http://www.ncbi.nlm.nih.gov/pubmed/8003328

Conditioners: (post # 168 - studies)

Styling Products:

- The mechanics of fixatives as explained by polymer composite principles: http://www.ncbi.nlm.nih.gov/pubmed/19450424

- Hair spray:

- (blog) http://science-yhairblog.blogspot.co...ir-sprays.html

- Dynamic hairspray analysis. II. Effect of polymer, hair type, and solvent composition: http://www.ncbi.nlm.nih.gov/pubmed/11567208

- Gel:

- Polymer composite principles applied to hair styling gels: http://www.ncbi.nlm.nih.gov/pubmed/19156332

- Assessment of styling performance in hair gels and hair sprays by means of a new two-point stiffness test: http://www.ncbi.nlm.nih.gov/pubmed/20939974


Hair Shine: (post # 133 - studies)

[meteor]

INDEX - PART 3

Hair Experiments:

1. Weight of hair:
- Gossamer: https://youtu.be/YW7yZrmLWdg and http://forums.longhaircommunity.com/.../t-137282.html (Dry braid ~350 g, ~12 oz, ~.77 lbs)
- Lucy's Corsetry: https://www.youtube.com/watch?v=Xduq...&nohtml5=False (Dry braid (48'' of hair) ~ 225 g (0.5 lbs), and Wet braid (not dripping wet) ~ 350 g (0.75 lbs), so the hair absorbed about 55% of its dry weight in water)
- Wusel: http://forums.longhaircommunity.com/.../t-137282.html (~70 g)
- JJJ / LadyLongLocks: ~ 255 g (9 oz) dry hair (60'') (http://forums.longhaircommunity.com/...=1#post2392236)
- Igor: ~ 250 g (thick, knee length hair) (http://igorsbelltower.blogspot.ca/20...headaches.html);
An average inch of hair weighs about 50 µg.


Theories:

1. Is curly hair more/less tangle-prone? Study: Why does curly hair get less tangled than straight hair? by Jean-Baptiste Masson: http://scitation.aip.org/content/aap...1119/1.2733683 (quick article on it: http://www.scientificamerican.com/ar...an-curly-hair/) (post # 29, post # 48, post # 49)


________________


Recently raised questions:

1. Do UV filters in haircare products work well to protect from UV damage? (post # 5)


2. Which oils can penetrate hair? Does olive oil penetrate hair? Are other fatty acids (other than lauric acid) possibly responsible for penetrating abilities of oils? (post # 14, post # 25)
- Coconut (both unrefined and refined, as long as it's not fractionated; ~ 49% lauric acid): "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."(Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage. - http://journal.scconline.org/pdf/cc2...175-p00192.pdf)
Maybe also:
- Babassu oil (~ 50% lauric acid)
- Palm kernel oil (~ 48% lauric acid)

Oils without lauric acid may still penetrate, though the instances are less documented (see below).
Olive oil can penetrate (probably due to its saturated and monounsaturated fat content), according to studies reviewed by Science-y Hair Blog: http://science-yhairblog.blogspot.co...coat-hair.html
According to this study (Investigation of penetration abilities of various oils into human hair fibers: http://journal.scconline.org/pdf/cc2...283-p00295.pdf), "In general, saturated and monounsaturated oils penetrate into the hair because of a compact molecular structure and the polar head group of the triglyceride molecules that constitute these oils. In a dynamic mode these molecules can reptate and squeeze through the CMCs. On the other hand, polyunsaturated oils do not penetrate into hair, most likely because of the more open and spread-out structures of their triglyceride molecules and because of the presence of multiple double bond."

See fatty acid composition of oils: https://docs.google.com/spreadsheets...=2&pli=1#gid=3

3. Can oils penetrating hair cause brittleness?
(post # 7, post # 25) Not likely. This study (Secondary ion mass spectrometric investigation of penetration of coconut and mineral oils into human hair fibers: Relevance to hair damage: http://journal.scconline.org/pdf/cc2...169-p00184.pdf) showed that "reduction in moisturization of the fiber does not make the fiber rigid because of the plasticizating action of the absorbed coconut oil."

However, oils do build up on hair. According to this study (Effect of oil films on moisture vapor absorption on human hair: http://journal.scconline.org/pdf/cc2...135-p00145.pdf), there is a reduction in moisture uptake and diffusion rates when oil film is formed on hair, and the thicker the film, the more pronounced the effect.

4. Do people who bathe less frequently have a healthier symbiotic community of bacteria on their skin? How is the population of bacteria on hair change depending on the type of hair care - shampooing, CO, WO, NW/SO, etc? What causes sebum to smell? (post # 37, post # 40, post # 48)

5. What is the evolution of hair strand thickness with ageing? (post # 47)

6. Is there a scientific study out there that deals with the question if the frequency of hair washes influences how quickly the scalp produces more sebum? (post # 63, post # 66, post # 67)
The regulation of sebum excretion in man: http://link.springer.com/article/10.1007%2FBF00560397
"The refatting curve of 21 test persons shows that the sebum excretion is highest during the first hour and decreases continuously with every following refatting interval. Refatting after regular defatting every hour reveals a constant excretion rate over 7 hrs. Thus the conclusion can be drawn that sebum excretion is regulated by the excreted sebum itself."

7. Is hair steaming damaging, useless or beneficial? (post # 85, post # 86, post # 87)

8. Is it less damaging to hair structure to cut hair when it's dry or wet? (post # 138, post # 140)

____________________


Additional Reading:
Chemical and Physical Behavior of Human Hair by By Clarence R. Robbins (2012) (post # 18)


Some Hair Science Related Blogs:
http://science-yhairblog.blogspot.com/
http://www.thenaturalhavenbloom.com/

[meteor]

Photo-Damage BACK TO INDEX

Quick summary:

Photo-damage is a type of environmental damage and is sometimes referred to as "photo-aging".
UV rays damage hair keratin, deplete lipid layer and make natural and artificial colors fade, while making white hair develop a yellow tint.
"Damage to hair due to UV light occurs due to free radicals or cysteic acid, which forms after UV radiation and breaks disulfide bonds."(Pande CM, Jachowicz J. Hair photodamage-measurement and prevention. J Soc Cosmet Chem. 1993;44:109–122)
"Continuous UV-light exposure results in dryness, roughness, sun-bleaching and breakage due to photo-oxidation."(http://www.ncbi.nlm.nih.gov/pubmed/11382847)
"UVB radiation is responsible for hair protein loss and UVA radiation is responsible for color changes."(http://www.ncbi.nlm.nih.gov/pubmed/19138021)
"Morphological damage is significant in UVB-irradiated hairs, while biochemical changes are greater in UVA-irradiated hairs."(http://www.ncbi.nlm.nih.gov/pubmed/18408872)

According to some studies, different hair types can show different degrees of susceptibility to photo-damage: for example, "it has been found that gray hair undergoes more severe UV damage and needs more UV protection than dark brown hair" (http://www.ncbi.nlm.nih.gov/pubmed/11382847) and "after UV irradiation, European and African hair samples exhibited more damage because they have less integral hair lipids. However, Asian hair samples have less damage." (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3582929/)

UV rays make chemical dyes fade faster:
"The loss of dye hair color typically occurs because of color wash-out during the daily shampooing process or can be initiated by environmental circumstances such as exposure to UV radiation which can break down the color molecule. It was found that the washing process is the most signifi cant factor in the removal of hair color, while UV exposure has a significant impact only after 90 hours of intense irradiation." - Protection of oxidative hair color fading from shampoo washing by hydrophobically modified cationic polymers (http://journal.scconline.org/pdf/cc2...217-p00238.pdf)

UV exposure increases hair's porosity:
"Chemical damage (oxidative bleach) nearly triples the hair surface area in the first minute of bleaching due to the increase in the number of pores, followed by a sudden drop after 10 min of bleaching from smaller pores breaking down into larger ones. In contrast, UV damage shows an immediate loss in surface area in the first 200 hr of exposure and a gradual increase as exposure time continues." (http://journal.scconline.org/pdf/cc2...303-p00315.pdf)

This morphological study (http://journal.scconline.org/pdf/cc2...151-p00156.pdf) shows that "UVA irradiation can penetrate deeply into the cortex, and so biochemical changes, including cuticles and cortex together, may appear greater after UVA irradiation. On the other hand, UVB cause severe morphological damage, confined to the hair cuticles because of its restricted depth of penetration." The study "shows relatively more destructive cuticular changes after UVB irradiation than after UVA, while disruptions of the intercellular lipid layer show similar results between UVA and UVB irradiation. However, in labile protein analysis, damaged labile hair proteins are much more observed after UVA irradiation than after UVB irradiation."


Photo-damage Studies:

- Photodegradation of human hair: a SEM study: http://journal.scconline.org/pdf/cc2...103-p00125.pdf

- About photo-damage of human hair: http://www.ncbi.nlm.nih.gov/pubmed/16465301

- UV damage of the hair: http://www.ncbi.nlm.nih.gov/pubmed/19138021

- Hair color changes and protein damage caused by ultraviolet radiation: http://www.ncbi.nlm.nih.gov/pubmed/15157906

- Photoaggravation of Hair Aging: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2938585/, http://www.ijtrichology.com/article....=99;aulast=Lee

- Photo yellowing of human hair: http://www.ncbi.nlm.nih.gov/pubmed/17627835

- Comparison of hair shaft damage after UVA and UVB irradiation: http://www.ncbi.nlm.nih.gov/pubmed/18408872, http://journal.scconline.org/pdf/cc2...151-p00156.pdf

- The ethnic differences of the damage of hair and integral hair lipid after ultra violet radiation: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3582929/

- Ultraviolet damage on natural gray hair and its photoprotection: http://www.ncbi.nlm.nih.gov/pubmed/11382847

- Protection of oxidative hair color fading from shampoo washing by hydrophobically modified cationic polymers: http://journal.scconline.org/pdf/cc2...217-p00238.pdf

- True porosity measurement of hair: a new way to study hair damage mechanisms: http://journal.scconline.org/pdf/cc2...303-p00315.pdf and seminar notes: http://journal.scconline.org/pdf/cc2...579-p00580.pdf

- Impairment of hair mechanical properties by sun exposure and bleaching treatments: http://www.ncbi.nlm.nih.gov/pubmed/15645109

- Photoageing of hair fiber and photoprotection: http://www.ncbi.nlm.nih.gov/pubmed/8003327

- Measurement and prevention of hair photoaging: http://www.ncbi.nlm.nih.gov/pubmed/15645087

- UV radiation: aggressive agent to the hair--AFM, a new methodology of evaluation: http://www.ncbi.nlm.nih.gov/pubmed/12858226


Damage Prevention: compact protective styles and hats, buffs, scarves, etc made of UPF-rated materials.

What to do about white hair turning yellow (from the sun and other factors): http://science-yhairblog.blogspot.ca...ht-blonde.html


____________

Open Question: Do UV filters in haircare products work well?
There are some studies that suggest that they are somewhat protective, but they were done on separate tresses, and I'm not too sure that they can cover the whole surface area enough to protect from UV damage without making hair look soaked in product and unpresentable. Also, how do they compare to things like simple oils and conditioners or hats?
Some studies (many aren't independent!) on UV filters and anti-oxidants for preventing hair damage from UV rays:

- UV Damage of the Hair: https://www.google.com/url?sa=t&rct=...O8odejGEfsb1pw

- Detection of UV Induced Free Radicals in Hair and their Prevention by Hair Care Products: http://www.gematria-test-lab.com/pdf...ion%5B1%5D.pdf

- A Diester to Protect Hair from Color Fade and Sun Damage: http://www.alluredbooks.com/sample_pages/ca_ch35.pdf

- Influence of antioxidants on the sun protection properties of hair care products: http://www.ncbi.nlm.nih.gov/pubmed/15645086
"According to the HPDSC measurements the antioxidants showed a slight increase of the peak temperature and therewith a hint towards a protection effect when used in a pre-sun or after-sun product. In contrast thereto some of the antioxidants reduced the tensile strength of sun care products for hair when added. A slight reduction in the lightening of natural hair color could be observed when antioxidants were present in the sun care formulations. The effect of antioxidants in sun care formulations used on dyed hair was strongly dependent on the shade of hair. The addition of some antioxidants yielded significant improvements of the protection properties of the used sun care product in some measurement methods."

Igor ran an experiment on shed hair using a product with skin SPF and a product with hair UV filters. After 2 months (re-spraying product once a day), she found that the skin SPF patch was darker than the control patch, and the hair SPF patch was lighter than the control patch.
Is it possible that the darkening was caused by product meant for skin simply building up on hair; and the lightening could be caused by hair UV protection product being simply not effective enough?
http://igorsbelltower.blogspot.com/2...xperiment.html
http://igorsbelltower.blogspot.com/2...-2-months.html

[school of fish]

What an excellent idea for a thread!!! Will be following this one keenly...

[Darkhorse1]

Also for people to note about oils. As of now, the only 2 oils that have been scientifically proven to penetrate hair are coconut oil and olive oil. This is due to the size of the molecular structure. Be careful with coconut oil! Coconut oil is the smallest of the oils on a molecular level. Therefore, it can penetrate the hair shaft the best. HOWEVER, this can damage hair and make it very brittle (protein over load) and snap off. I almost did this to a test part of my hair (finally listening to my hair and it's loathe of proteins).
Coconut oil is known for strengthening hair, Olive oil, since it's molecular level is slightly larger, is known for moisturizing. Other oils, depending on their molecular structure, likely just sit on hair unless you allow overnight to absorb.

[mermaid lullaby]

Thank you Artic!
This is a great idea!

[gthlvrmx]

I am happy about this thread! I love hair science! I will be following this thread!

[meteor]

That's great, guys!

Darkhorse1, thank you! I didn't know that about olive oil. Do you know if there are any links on penetrating abilities of olive oil (or any other oil, for that matter)? Does anybody know?
I know for sure about coconut oil, and I think some other oils may fall into the category of penetrating oils (palm kernel, babassu), because they contain a lot of lauric acid, as well, but I don't know if any other types of fatty acids can be responsible for penetrating abilities.... Maybe all the medium-chain tryglycerides (lauric, caprylic, capric, caproic acids) can penetrate hair?

I thought coconut oil just reduces the hair's loss of its own protein, and this means that the hair doesn't become as damaged quickly. Protein loss in that study was used as a measurement of damage: i.e. the more protein loss, the more damage was incurred; the less protein loss, the better the integrity of hair was preserved. Uncontaminated oil is 100% fat and 0% protein, so it can't really deposit protein. However, I know many people report getting "protein overload"-like symptoms from using coconut oil... hmm, I wonder, if it has something to do with simple build-up or the oil not agreeing well with that hair or maybe the fact that coconut oil solidifies at ambient temperatures (below 24°C) and feels a bit grabby/tacky compared to runny oils that don't solidify like that?