How Coarse Hair is Different

One of the greatest differences for wide or coarse hair vs. fine hair is an element of flexibility. In cosmetics science, it is sometimes called plasticity.

Oils, conditioning agents like cationic quaternary surfactants, fatty alcohols like cetyl alcohol and “butters” like shea butter, oils and silicones all add plasticity to hair. So might proteins, amino acids and humectants by promoting good hydration.©Science-y Hair Blog 2013

When we think “plastic” in everyday life, we usually think of hard or semi-hard plastic boxes and containers. But in biology, physics and engineering, “plasticity” means an object has flexibility, it can be molded and is pliable. In this post, I suggested that one of the frustrating issues for fine hair is that it can have an excess of plasticity – it is very easily deformed.©Science-y Hair Blog 2013

Hair which is coarse (wider hair shaft), resists changing shape. It is not as super-flexible as fine hair. So fine / medium hair and coarse hair are fibers with different behavior and different needs. Fundamentally, they are made from the same ingredients, but the expression of the ingredients is different.

If hair is lower in plasticity/flexibility, it is difficult to change it’s shape – hard to curl straight hair, hard to straighten curly hair. It will behave differently in a variety of situations and to a variety of treatments. It may take extra effort to get coarse hair with a wave or curl pattern to lie smoothly, which is a prerequisite for shine.

Medium to wide hair resists bending,
rather more like coiling up a garden hose.

Coarse hair has more internal support than fine hair. It holds its own shape quite well, it is less likely to be weighed down. You can see in the graphic (below) how much more brown (hair cortex) there is with a wider hair than a narrower (fine) hair. This is why wider hairs are less pliable. These unrealistically round hair sketches were easier to do with the software I was using when this post was written. Hair is usually oval to elliptical in cross section. I like to imagine fine hair like trying to wind or coil up a cotton rope and wide/coarse hair like coiling up a garden hose, which resists the bending and tends to want to coil in it’s usual pattern. 

See notes to the right. I know - hair is elliptical. But this is easier
for me to "draw!"

In the fine hair post, this visual aid represented the problem of how much more conditioner or oil clings to fine hair vs. wider hairs, relative to the mass or volume of the interior of the hair. It works the other way around for wider hairs – plenty of conditioner is needed to make this hair type feel soft and smooth and bendable because the conditioner contacts so much less of the whole of the hair.

Plasticizers in hair work like lotion or cream on dry skin – soften, seal in moisture, or attract moisture. They also add an element of pliability and flexibility (plasticity) that the hair may not have on its own. Like oiling leather or polishing a dry leather shoe, something inflexible becomes flexible, softer and glossier with the addition of a plasticizer (oil or shoe polish).

©Science-y Hair Blog 2013

If you have ever used a leave-in conditioner, smoothed coconut oil or avocado into your hair, left in a lot of conditioner – and had your hair become softer, springier, better defined as a result – you can chalk that up to the increase in plasticity/flexibility.

And if you want your hair to have more pliability, you need emollients (oil or conditioner) – not only to act as an occlusive (prevent moisture loss because hair + water = flexibility), but also to help your hair stay soft and to align itself with its neighbors which increases shine and wave/curl definition.

If your hair has kinking in it, the added plasticity of oils and conditioners also helps prevent breakage. Each little bend and twist of the fiber (kink) can be a point of weakness in the fiber. The more abrupt a directional change, the weaker that spot is. 

©Science-y Hair Blog 2013

Here’s a final thought. If you have fine hair, which is dry or porous or damaged, it may act like wider hairs and need more plasticity too, but fine-haired people can usually get away with much less.

Some parting thoughts: Usually you can tell if you have coarse hairs. They feel solid between your fingers. You can see them easily when held up against a contrasting background. When you bend coarse hairs, they like to spring back. Some coarse hair is quite pliable and bendable, some feels more rigid and wiry. Especially when hair is light-colored or not thick (densely packed) on your head or it is soft - it may not seem coarse when it actually is. It is a myth that all coarse hair is rigid or feels wiry. Coarse hair can be slippery and silky or springy and soft, or wiry.

More Wavy Physics

Why does some wavy hair curl, and others does not? Some wavy hair will curl with certain styling products, with humidity – just plain unpredictably on some days and not on others. In this post the story was about how fine hair often does not have the structural support to maintain a wave of curl if there is weight on it from the sides or weight from length (or water or styling products). Many people with wavy hair, especially wavy hair that does not wave and curl consistently have fine hair and that explains much wavy-haired frustration.©Science-y Hair Blog 2013

But this doesn’t explain how people who have average-width or wide (coarse) hair can have loose waves too. Or how wavy hair can be fairly curly. Imagine driving a car or a bicycle. You turn the steering wheel or handlebars just a little. You will begin to turn in a large circle – you may run out of space to complete your turn. If you turn the wheel more sharply, you will make a sharper turn and go around in a tighter circle. That’s pretty much the explanation - but I've got a visual aid below.

©Science-y Hair Blog 2013

In this post, we dug into the biology of how hair curves. You have these variables:

1) A large variation in the way various proteins are arranged on different sides of the hair means a smaller curl circumference (bouncy curls), but it can also mean a curl that is more robust and doesn't pull out easily vs. a curl that drops out without a lot of styling products. And a smaller variation in the way these various proteins are arranged means a larger curl circumference (undulating waves). The intensity of the curl as determined by these variables will determine how well your hair holds a curl. Generally, tighter curls resist gravity and weight better than looser ones because the curve of the fiber is stronger.

2) The width or diameter of the fiber determines how structurally well-supported it is and how well it can withstand forces from the outside (other hairs, gravity) – fine hair has more difficulty maintaining the spring in its curls than does wider hair.

3) A hair has to wave about 3 times in order to form a curl. So if your wavy hair has the crests of each wave 3 or 4 inches apart, you need plenty of length to get your hair to make any sort of spiraling curl, or even for the waves to make themselves quite clear.

In this attempt at an illustration (I make no apologies, I am not a graphic designer), you see in dark blue a loose-ish curl circumference. Let’s say the crests of the waves are 2 inches (about 5 cm) apart, which is quite wavy hair. The circle then is probably about 1 inch (2.54 cm) in diameter – but gravity stretches that circle into a spiral. The arrows indicate where each wave appears so that you can see where a wave’s crests and troughs fits into the context of a curl.

Below this in green is a much larger circle/curl. Let’s say the crests of the waves are about 3.5 inches apart (9 cm) and the circle outlining the curl is around 2 inches in diameter. These are loose, glamorous, “beach” waves. Because of the large area circumscribed by the curl, when exposed to gravity, it will be pulled into a loose wave or very gentle spiral. The twist on the hair may not be readily discernable under some conditions. If you give hair like this enough length and relieve it of its weight by having layers, or using a diffuser (on low temperature) to press hair towards your head while you dry, and use styling products such as hair gel to help the hairs hold together while they dry, you will see some twists and turns.

©Science-y Hair Blog 2013

Curls and waves are really the same thing, but with a different “turn radius." I know that should be "radii" but it just felt way too pedantic to put into a sentence. Not that using the word "pedantic" isn't also a bit priggish. At least by USA standards.

Waves are curls, it’s a matter of physics. 

What's Cookin': Super Smooth Flax Curl Cream

If you have dry or tightly curled or coarse (hair that has a wide diameter) or kinking hair, you might like this recipe! It does wonders for gray hair too. Defines, softens, de-frizzes, holds gently, adds shine and enhances your hair's natural texture.

Warning, Version #1 has one (okay, maybe 2) Uncommon Ingredients. Version #2 does not.
It transforms husband's kinking, mind-of-its-own hair into shiny, soft, well-defined waves and curls that just get better as the day wears on. It makes my more silky hair a little heavy, I cannot use too much of it.
Here's a link to a stronger-hold recipe, if your hair demands more hold:  Flaxseed Curl Cream.©Science-y Hair Blog 2013

Ingredients for Super Smooth Flax Curl Cream:
- Flaxseeds
- Water (preferably distilled)
- Coconut oil for dry or porous hair, apricot kernel or grapeseed oil or a mixture of your favorite lighter oils for easily weighed-down hair.

Variation #1: BTMS-25 or BTMS-50 flakes (BTMS contains Cetyl alcohol and Behentrimonium methosulfate, an ingredient used in formulating hair and skin products. If you use this ingredient, make sure it does not contain ingredients other than the 2 mentioned - check with the manufacturer or supplier).
OR 
Variation #2: A creamy, thick hair conditioner of your choice, thin or runny conditioners may not work as well.

Both variations:- *Optional, not necessary: Add a tiny pinch - about 1/32 of a teaspoon citric acid or "Fruit Fresh" to make a lower pH product, Ideal for porous, dyed or highlighted hair.
- Hydrolyzed protein (optional, some hair types may feel too stiff or become dry and brittle with protein added) such as Colorful Neutral Protein Filler

©Science-y Hair Blog 2013
Step 1: Make the Flax Base (Variation 1 and 2)
Boil together 3 tablespoons (1/4 cup) flaxseeds and 1 1/2 cups distilled water, stirring occasionally, for about 5-6 minutes. The flax should be sinking and the gel should be starting to look like thin threads as it drips from your stirring spoon or fork, but it should not fall in thick strings. (Optional: soak the flaxseeds in the water for about 3-6 hours before boiling for a stronger-textured gel).
Strain the seeds out of the gel with a colander or wire strainer.
You should have about 3/4 to 1 cup of gel (if not, use more water from the beginning next time and for now, put the gel back in a pan, add enough water to equal 1 cup and re-heat and whisk).

Step 2 and 3, Variation #1: Meanwhile, in a double boiler (such as a Pyrex measuring cup in a double boiler or in a pan on a rack) heat 1/2 teaspoon coconut oil (or other oils) and 1/4 to 1/2 teaspoon BTMS (Cetyl alcohol and Behentrimonium methosulfate - a cationic, emulsifying conditioner) just until it melts, lower the temperature on the stove and hold at 140° F (60°C) for 15 minutes (for example - while you boil the flax seeds).

After that 15 minutes is over, add the flax gel and optional citric acid if using to the double-boiler in which you have melted the oil and conditioner. Blend well with a stick (immersion) blender.

Steps 2 and 3, Variation #2: Directly to the strained flax gel add 1/2 teaspoon coconut or other oils so that it melts. Then let the gel cool until it's comfortable to touch. When the gel is cool, add 2-3 tablespoons conditioner, optional citric acid if using and whisk well, or use an immersion (stick) blender or an ordinary blender to mix gel, oil and conditioner.

Optional protein step: When cool enough to touch, add 1/2 teaspoon hydrolyzed protein such as Colorful Neutral Protein Filler, or hydrolyzed protein of your choice.

Step 4: Pour into a clean, sterilized bottle with a cap (it's still slimy, this is the best way to dispense it) and refrigerate - this should keep for 2 weeks. You can freeze part of the gel for a longer "shelf" life. Clean jars work well too - scoop the gel out with a clean spoon instead of your fingers to avoid contamination.
©Science-y Hair Blog 2013
Too thin and slippery? Need more hold? This recipe is rather thin and slimy. To thicken the gel and add a little more hold, do this before you add anything else to the gel.
Mix any of these thickeners with 1 tablespoon cool water to dissolve or disperse:
1/2 teaspoon pectin - the kind for making jam and jelly without sugar but watch that the pH doesn't go too low
or
1/2 teaspoon xanthan gum
or
3/4 to 1 teaspoon arrowroot starch (flour) or cornstarch

Return the gel to a pan over medium heat (or in a double boiler) and add the thickener-water mixture. Heat the gel while whisking or stirring until the thickener is dispersed and not lumpy - for the starches you want to see the gel get mostly clear and begin to thicken. Use an immersion blender for quicker blending.

To use: Apply to damp or wet hair as you would any hair gel. Top with a stronger-hold gel if you prefer. The flaxseed gel (and protein) provide moisturizing, shine and light hold. The conditioner adds softness and light hold as well as frizz control. The coconut oil provides softness, pliability and shine and helps trap moisture near the hair.

Application tips: For the absolutely smoothest result, comb this gel (with a wide-tooth comb, or your fingers) into your hair or smooth it over small sections, making sure all strands are well-saturated. Then scrunch if you like (slowly and gently let hair fall into your palm and press upwards towards your head so that the hair can form it's waves and curls in the palm of your hand, then give a gentle squeeze for 3-5 seconds once it's all up near your scalp. Just as slowly, release the hair). Blot out any excess moisture and air-dry or lightly diffuse-dry.
To elongate curls: Apply the product to dry hair to style or to refresh.

Trial size: Assuming you already have some flaxseed gel.
1/4 cup of strained, homemade flaxseed gel (thickened or not)
1/8 teaspoon coconut oil or grapeseed oil
1 1/2 teaspoons conditioner

Mix together in a clean container (if the coconut oil has solidified, warm it first). Refrigerate the "leftovers" if you want to use them later.

Enjoy!

How Fine Hair is Different

Everybody’s hair is different. It’s really the combination of chemical and physical properties of, and environmental influences on your hair that make it unique, no matter what your heritage or what you do to your hair. Most of us have a mix of hairs on our heads – different diameters, different textures, some variation in color from follicle to follicle. But if you can get over aesthetics - hair color and the visual stuff, there’s some fun physics/engineering in there. I have mostly fine hair and those of us who do know it is not the same to work with as hair which is not fine, so I dug in to try to point out the obvious.

©Science-y Hair Blog 2013

String cheese separates into sections - a
visual aid for hair diameter.

Fine hair has a smaller diameter than average (somewhere between less than 50-70 microns in diameter, depending on the source you consult – I feel it’s closer to the lower end). This doesn’t tell us much unless you’re accustomed to measuring things in microns (micrometers). So I’m falling back on a cheese analogy. Think of fine hair as a few “strings” from a piece of string cheese. Medium or “average” hair could be half the piece of string cheese and coarse hair or larger-diameter would be the entire piece of string cheese. If you want to imagine fine hair being less stiff than average or coarser hair, go right ahead because that could be an advantage (fine hair can feel silky-soft and weightless) or a disadvantage (it can be too soft to easily hold a style, easily “dented” by bobby pins and ponytail holders).

Diameter influences how easily you can de-form (deform, hyphenated so you’d read the meaning) fiber. You could easily bend or reshape a few strings of string cheese. Half the piece (representing “average diameter” hair) would tend to hold it’s shape and deform less readily and the entire piece would be thick and dense enough to resist deformation even more. This character of individual hairs has a lot to do with how those hairs behave as a mass. Fine hair, easily deformed by outside forces, is more susceptible to the effects of gravity, the weight of other hairs and of water, oils and conditioners.

©Science-y Hair Blog 2013

Because fine hair is easily deformed (collapses under weight) it tends to hang with less body or volume than coarser hair. Even wavy or curly hair, which tends to have more body than straight hair because of the waves, will look less full if the hair is fine because the hair has more difficulty maintaining its wave pattern if there is weight on it from the sides or the weight of length.©Science-y Hair Blog 2013

The exception is hair with a very strong wave pattern (tight curls) in which the strength of the waving in the fibers helps them resist collapse.

More Physics and a little Geometry

All hair is covered by several layers of cuticle. If you mentally wrap these layers of cuticle around a few strings of string cheese versus an entire piece of string cheese, you can see that there is a lot less cheese inside the “fine hair” version than there is in the “coarser hair” version. That means there is more surface area (cuticle) relative to mass (cheese or hair cortex) in fine hair.

©Science-y Hair Blog 2013

Because fine hair has more surface area compared to mass or inner volume than medium or wider hair, things like oils and conditioners that either coat the hair shafts or bond to them (cationic conditioners and polymers) have more surface to coat per mass of hair. This is why oils and conditioners can weigh fine hair down more readily – first, fine hair is more easily deformed and second, it has more “surface” per mass of hair for things to coat or stick to.

In the graphic above, you see a fine hair (left) and a medium to wide hair (right). The blue dots surrounding the hair represent “units” of a conditioner or oil – or cuticle. This is a numberless unit, but it worked for the scale-less image – so just humor me. The fine hair is surrounded by 14 units of conditioner and the wider hair has 21 units of conditioner (or cuticle). The dots running across the hair indicate diameter. Here’s the geometry – the area inside the hairs (calculated by using pi!) is 12.57 for the fine hair and a whopping 38.47 for the wider hair. Now for a ratio, because this is where it makes sense; the fine hair has a ratio of conditioner or cuticle to “area inside of hair” of 1.1 to 1 (slightly more blue than brown) and the wider hair has a ratio of 0.55 to 1 (more brown than blue). Because hair cortex is where the "stiffness" comes from, fine hair is not as stiff or well-supported. And because cuticle is where products tend to be, you can see from the graphic how fine hair can suffer from an overly-large dose of anything that makes this already-soft hair even softer. It's more difficult to overwhelm the wider hair with products because it's internal structure, the cortex shown in brown, is larger and provides more support - hairs which are thicker are less deformable.

Solutions for Volume and Style©Science-y Hair Blog 2013

One way to work around the “weight” problem in fine hair is to have layers in your hair. This is the engineering part. If you want to reduce the load on parts of your hair so it is not collapsing under its own weight, then you must remove the weight. Layers do this for fine hair. In wavy or curly hair, the trick is to have those layers “long” so they can still execute their twisting shape. Where the weight from hairs above collapses the wave pattern, the hair can be cut shorter to reduce it’s weight on the areas beneath. Then both layers benefit from the reduction in weight. Think about it – the top layers of your hair, being cut a little short in layering, lose the weight of length because a hair growing from the top of your head down to, perhaps, your shoulders, is much longer than a shoulder-length hair growing from your hairline. So this hair is lighter. And the hair beneath benefits from not being mashed by the hair from above. That is why wavy hair and curly hair look good layered and look bulky when worn all-one-length. A haircut is truly a feat of engineering as well as a bit of artistry.©Science-y Hair Blog 2013

Chemical and Physical Behavior of Human Hair 

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

Yin N., Kissinger RH., Tolgyesi WS., Cottington EM., 1977. 

Journal of the society of Cosmetic Chemistry 28, 139-150