Mechanical Hair Damage

Hair has a lot of enemies. That's why it keeps growing. Sunlight, chemical treatments, packing tape that your brother sticks in your hair because he thinks it's a great joke - all hard on your hair.
Certain grazing animals have teeth which grow throughout their lives because the grasses they eat contain a lot of silica, which grinds down teeth and the initial parts would soon be worn out.
©Science-y Hair Blog 2013
People have hair which keeps growing to keep our heads covered, even if our hair should be broken or pulled out. You only need see a bald person who was outside with no hat or sunscreen to understand the severity of the sunburn you can get on your scalp. Sunburn leads to water loss from skin, unhealthy skin, potential for infection. Not to mention an overheated scalp can make an overheated person and hair may help us modulate the temperature of our heads. Where we keep our brains. Our constantly-growing hair is always growing and replacing itself because nature expects it to wear out.
©Science-y Hair Blog 2013
The damage nature anticipated the most is mechanical damage. Spend some time in tall grasses, brambles and briars, dense woods down by rivers and you'll catch your hair (and skin) on many things. Branches and shrubs and grasses will catch and tangle your hair. Seeds and twigs and thorns will be caught in your hair and clothing which will anchor firmly without speedy removal.
If that's not your lifestyle, then think of washing your hair - there's some rubbing of hair fibers against each other, your scalp and fingers. Strong shampoos can dissolve oils and free hair's proteins. Combing and brushing create far more friction, and wet combing creates more friction than dry combing. Sleeping applies a massive amount of friction to hair. Sliding a hair under the weight of another hair alone can cause erosion of cuticles. Wearing hair up in a ponytail daily, even with fabric-coverd ponytail holders can result in the same sort of damage because of the friction of the hairs rubbing as you move. Rubbing on collars of shirts and hats is another source of hair damage.©Science-y Hair Blog 2013

We can weaken our hair with too-frequent shampooing and chemical treatments or make it more porous, but it is our handling of it and the forces applied to our hair (knots, twisting, pulling, rubbing, pressure) that can break it, dull it and of course these things also lead to dehydrated, porous, less-healthy hair.©Science-y Hair Blog 2013

You cannot avoid all mechanical damage, but you can try to prevent it - which is important if you want healthy hair without having to add a lot of products to it, if you want your hair to grow long, or if it has already been damaged and you want to prevent further damage.©Science-y Hair Blog 2013

I'll be posting soon with how to line a hat with satin to reduce the friction on your hair and scalp. I didn't believe the difference this could make until I started lining hatbands with satin ribbon. I just snagged some fabric from my local fabric store! If you are accomplished at sewing, please overlook that upcoming post. I only sew when I need to.

Source: Chemical and Physical Behavior of Human Hair 

Robbins, 1994. 3^rd Ed. Springer-Verlag, New York

Formaldehyde - Spotlight on Preservatives

I’m writing this because I have sensitive skin and allergies and so many hair and skin products are “off-limits” to me because they contain preservatives which make my skin itch, burn, turn bright red, break out in a rash. Actually, I'm writing it because 3 more products I love have started to make my skin itch and that annoys me because now I have to come up with new homemade recipes or search for something non-itchy and not-expensive.©Science-y Hair Blog 2013

One of the best-known skin offenders are preservatives related to formaldehyde. You know, a part of the recipe for embalming fluid. Yep, it’s that nasty.

I’m not going to mention the formaldehyde in hair smoothing or straightening products (except that I just did)! These are sources of formaldehyde which are not only skin-contact problems, but also unhealthy to breathe for the person having their hair straightened and for the stylist doing the work.

©Science-y Hair Blog 2013

You won’t find pure formaldehyde in your hair (or skin) products (except maybe for nail polish), you’ll find formaldehyde-releasing preservatives instead. Why? Because they’re some of the most effective preservatives out there for preventing the product from playing host to bacteria and fungi which would break it down, reduce shelf life and could introduce dangerous microbes to the body.

©Science-y Hair Blog 2013

Your greatest exposure to formaldehyde in life is actually from building materials, carpets, foam insulation and other man made materials (for example, plywood or fiberboard is partly manmade whereas solid wood planks are not – and have become far more expensive than the former). And the risk is that the formaldehyde is released as a gas which you breathe and at high concentrations this can cause cancer (people who consistently breathe such high concentrations include morticians and some biologists).

In cosmetics and hair products, formaldehyde-releasing preservatives can be skin irritants or allergens. If you use a product and immediately – or even over time, begin to experience itching, redness, burning, a rash or outbreak of acne, you may want to consider these preservatives as possible causes:

©Science-y Hair Blog 2013

Imidazolidinyl urea

Diazolidinyl urea

dimethyl-dimethyl (DMDM) hydantoin

Quaternium-15

2-bromo-2-nitropropane-1,3-diol

Sodium hydroxymethylglycinate

A small number of people have a sensitivity to formaldehyde-releasing preservatives (3% to 9%). Imidazolidinyl urea and Diazolidinyl urea may be less irritating than DMDM hydantoin, quaternium-15, and 2-bromo-2-nitropropane-1,3-diol, but all release formaldehyde. These preservatives are officially  listed as “probable carcinogens,” although the greatest risk comes from inhaling the gasses. Less research has been done on transdermal (though-the-skin) absorption, although the formaldehyde released appears to have the potential to be absorbed through the skin. The National Academy of Sciences is disputing the U.S. Environmental Protection Agency’s position on formaldehydes as possible carcinogens in cosmetics. In science, you need very clear proof of cause and effect which can be produced and reproduced in clinical tests – especially when you are declaring a useful product to be dangerous (because the bacteria controlled by formaldehydes can also be extremely dangerous). Meanwhile these preservatives are still widely used, particularly as alternatives to paraben preservatives which were very weakly associated with breast cancer (see this post for more), even though parabens are not as likely to cause skin reactions (in one study, only 0.6% of people tested had a skin reaction to paraben preservatives – compared to 3-9% for formaldehyde-releasing preservatives) and unlikely to be related to breast cancer unless well-designed research can demonstrate a link.

©Science-y Hair Blog 2013

Avoid formaldehyde-relseasing preservatives if you suspect they cause you any skin reactions. And be aware that you can use a product for months (even years) before you experience a problem, or it can appear right away – like a skin medication I used which caused my face to turn bright red and burn for 6 hours after application, and I used it for weeks before I realized it was a problem with the preservative and not the intentional effect of the medication! Live and learn.

Another tip: Open your windows whenever you can, even if just for a short while – let the wind in and out. Especially in a new house or when you have new carpet or new furnishings. You don’t want to breathe all the formaldehyde which is gassing off these products.

Autumn to Winter Hair and Humidity

This post is timely to those of us in the Northern Hemisphere - to our friends and family in the Southern Hemisphere - hope you are enjoying spring into summer!

Humidity is water vapor suspended in the air.

How humidity is measured:

Dewpoint – the temperature at which the air is saturated with as much water as it can hold, and so dew (or fog) forms. Dewpoint tells us the most about how dry the air is. Unless a new air mass moves in, the dewpoint can stay the same all day. This is what you want to watch to know just how moist or dry the air is.

Dewpoints below 50° F (10° C) are “dry.”

In the 50s  (10-15° C) is “comfortable”

60-65° (15- 18° C) is “muggy”

65-70° (18-21° C) is “humid”

70° (21° C) and greater is “oppressive” – rainforest-y - you feel you need to grow gills

This is important for hair because dewpoint tells you how much moisture is in the air. Except for hair which has a very strong curl pattern, low moisture in the air tends to lead to flatter, less defined wavy or curly hair.

When researchers measure the effects of air moisture on hair, they use relative humidity. Partly because that’s what can be manipulated in the laboratory. Relative humidity changes throughout the day as the temperature changes because it’s a measure of how much moisture there is in the air relative to how much moisture the air could possibly hold. The warmer the air, the more moisture it can hold because air “expands” as it heats and that means you can cram in more water molecules.

Let's say you have a box in a laboratory at 74°F (this experiment was real). Add hair which has previously had all the water removed. Set the relative humidity at 29% and the hair will then take on moisture from the air so that contains 6% moisture. This is very dry – your mouth and nose and lips would feel parched. So here's how it stacks up:
At 29% relative humidity, hair holds 6% water

At 40% relative humidity, the hair holds closer to 8% water

At 50%, the hair holds about 10% water – 40-50% is the “comfort range”

At 65%, hair holds around 13% water – at 65% relative humidity, the air starts to feel “wet”

At 70%, hair holds close to 14% moisture©Science-y Hair Blog 2013

Note the temperature never changed during the experiment. In real life the temperature fluctuates throughout the day and the dewpoint tends to stay the same. But in winter in the high latitudes, away from the humid coastal areas, it’s pretty safe to say that you won’t encounter relative humidity above 50%! If you have a thermometer or humidistat in your home to measure humidity indoors or outdoors, it is measuring relative humidity. I used this experiment to demonstrate how much less water your hair can hold when the air is dry. ©Science-y Hair Blog 2013

When your hair has a lot of moisture from the air around it, it stretches more and bounces back less readily. Like worn-out elastic. Stretching damages hair. If you pull on a piece of taffy or chewing gum, you can see how the outer surface breaks. This is also what happens to your hair (more or less).

Even though hair can stretch more when it has absorbed more moisture, it takes more force to make it stretch in high humidity than in low humidity. In dry air a smaller stretch (or pull, or tug with a comb or snag on a button) will damage hair than in humid air.©Science-y Hair Blog 2013

Temperature also makes a difference. At higher temperatures, it takes more force to cause hair to break and at lower temperatures, less force is required to break or otherwise damage your hair.

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So when it is cold and the air is dry, your hair breaks more readily than when it is warm and humid.

©Science-y Hair Blog 2013

How to prevent hair breakage in cold, dry weather?

You need to plasticize your hair! “Plastic” means pliable and flexible. Oils, fatty alcohols, silicones, cationic surfactants (in other words, hair conditioners) can give your hair the desired flexible quality and help prevent tangles. Humectants may or may not be helpful for hair. If you like humectants, you may lean towards those that are polymers or "film formers" (aloe vera, flaxseed gel, vegetable “gums” like guar, xanthan, carrageenan, panthenol) rather than humectants like glycerin. Conditioners may prevent some loss of moisture to the air from your hair and definitely help prevent breakage due to tangles and rubbing on clothes, scarves and hats.©Science-y Hair Blog 2013

An ounce of prevention is worth a pound of deep conditioners:

Truly the best protection for your hair in low humidity and cold weather is to protect it with a warm hat, a scarf or hooded scarf. These hold warmth and moisture around your hair so it is not exposed to extremes.©Science-y Hair Blog 2013

Other interesting humidity tidbits: When hair is surrounded by ample humidity, as it is taking on water, it swells and also lengthens slightly. As your hair is absorbing moisture, a whole bunch of things can happen depending on your curl pattern, the amount of water vapor in the air, the temperature, and how porous or damaged your hair is. If it’s not too overpoweringly humid, your waves and curls may be more defined and more bouncy as they are hydrated by the water in the air. As the humidity creeps up, your hair may absorb far more water and begin to lose its curl pattern, getting big or puffy or frizzy (undefined) or become limp. When your hair swells with water, the resulting disruption of the cuticle (the scales are “lifted up”) causes hair to look less shiny. In this state, it is more prone to tangles. Very porous/damaged hair can potentially hold more water than not-porous or little-damaged hair. Damaged or porous hair is more prone to frizz in high humidity than healthy hair. But in general, wavy and curly hair gets bigger, frizzier, and less defined in very high humidity.

©Science-y Hair Blog 2013

For those of us with wavy hair or loose curls, low humidity can dramatically change our hair’s curl pattern. The hair just doesn’t have the moisture it needs to express a defined wave pattern. Lock in moisture after cleansing with rinse-out and leave-in conditioners or oils, use a humidifier in your home.

Source: Chemical and Physical Behavior of Human Hair 

Robbins, 1994. 3^rd Ed. Springer-Verlag, New York