Volume 1 - Hair Types and Anatomy
Introduction to Hair Anatomy and Types 💇
Written by Demi Rivera
No one head of hair is the same! All of us have a unique hair type, density and porosity. What are the differences? What matters to each hair type in terms of care and styling? I'll give you a run down! What kind of scalp do you have? Is your hair REALLY damaged or is it just dry? Knowing your hair and scalp type can make it easier on you when buying product and styling, to achieve healthy looking hair.
DISCLAIMER: I am a licensed professional cosmetologist in Colorado, I am NOT a medical professional, and I am not able do diagnose, advise or treat any illness or health-related issue beyond the overall health and appearance of hair. All of the following information is gathered from my schooling, professional knowledge and researched sources online. For more pressing or serious issues, please visit a dermatologist or primary care physician.
Scalp TYPE refers to the skin on your head. What does it look like 12-24 hours after washing? If it's itchy, tight feeling or has dry/flaky skin, your scalp is DRY. If you have oil buildup fairly quickly after washing, you have an OILY scalp. A NORMAL scalp is one without oily buildup, and without dry flakes or itchiness. The difference between a dry scalp and dandruff comes down to a medical difference. Dry scalps may have small flakes of dry skin fall from the scalp, although they are usually white and dusty. (Look out for a future blog post about scalp care)
True medical dandruff is typically a fungal issue. It can be identified by a sore, itchy scalp that has red or even purple hues, and often oily, big flakes that can be yellow to off white, sometimes it has an accompanying odor. If you do not have these symptoms associated with your dry scalp, that's all it is, a dry scalp!
This cannot be diagnosed by a hairstylist and requires a dermatologist to identify, diagnose and prescribe treatment. Sometimes it can be chronic, if you take certain medications that may have a side effect such as that. Here's an image of the differences.
-Here in Colorado, most people have a combo of the dry AND oily scalps/skin. Because of our lack of humidity, our bodies often over-compensate for the lack of moisture by becoming very oily as a defense mechanism. This is something you can train your scalp out of, but embracing the natural oils is also a great thing to do at least once or twice a week, (See my Instagram reel for my easy at-home scalp oil treatment) allowing the micro-biome of our scalps to thrive. Drinking enough water and avoiding hot showers on the scalp can slow down oil production and dry flakes as a result of being dried out and possibly scalded.-
Hair TYPE refers to the texture and curl pattern of an individual hair on your head. What does it feel like? Is it fine, silky, rough or wiry? Do you have a curl pattern or do you have stick-straight hair? If you have a curl pattern, there's a codename for what type you have! Each individual hair strand can have different diameters, which creates the "Fine or Coarse" category.
Fine hair is sometimes baby-thin, soft and usually has trouble holding body or volume. It dries somewhat quickly, and chemically processes more quickly. With this also comes the potential for more or easily obtained damage. It can be easily dried out by heat styling and often times needs to be trimmed more frequently than coarse hair, as it can obtain split ends more quickly as well. Personally I recommend trimming finer hair types as soon as 5 weeks between appointments, 4 weeks if you use a lot of chemicals or thermal styling. Fine hair often cannot absorb a lot of styling products, oils and moisture products must be used sparingly and only when necessary. Fine hair should NEVER be heat styled using temperatures above 300 Degrees on any iron.
Medium to Coarse hair types have a hair shaft that is thicker in diameter than fine hair. It typically has more layers of cuticle (double if its grey hair). Sometimes the cuticle is spread open, which is what is the main cause of frizz. This can happen even if you have straight coarse hair. Coarse hair requires a lot more moisture and care, but is also more resistant to chemical processing and heat damage. If you have coarse, thick hair, it will likely not air dry for hours and hours.
Coarse hair is also usually more porous, which means it has the ability to absorb water and product at a quicker rate, but also may not hold onto moisture and color for as long. I recommend trimming coarse hair 6-8 weeks apart. It requires heavier moisture (such as an intense moisture mask once a week, and regular use of professional hair oil or serum)
Porous hair often lacks the protein and bonds to keep the cuticle closed with the color stored under it. Any heat level is recommended for coarse hair, particularly if you have frizz. Remember to use a heat protectant before any heat styling is applied! If you have porous hair, your hairstylist should let you know, particularly if you are doing a color service. Porous hair can process and absorb color very quickly. Blonding and lightening services will swell the hair cuticle and cause a little porosity, but this can be tamed and sometimes reversed with the proper treatment. Certain professional toners and hair color such as Redken Shades EQ, are intended to fill the gaps in porous hair, and lay the cuticle somewhat more flat. Bond building products are great for this as well!
What is your Curl Pattern?
This can help you to select the right products and care for your curls. If you have straight hair with NO curl pattern, this is known as 1A hair. This goes all the way up to 4C curls which are finely-coiled curls. Truly stick straight hare is very rare, and is typically a fairly strong gene. Air dry your hair after washing, comb the tangles out and leave it be, without touching it or continually brushing it. As it dries, use this tool to compare any bevel or shape your hair takes.
Hair DENSITY refers to how MUCH hair you have on your head. This is what we mean when we talk about 'Thick or Thin' hair. One way to test this knowledge between friends and your own hair, is to compare ponytail sizes!
A low density ponytail will indicate thinner hair types, the circumference of this ponytail would likely be less than 2 inches. (Like mine lol)
A medium density ponytail will be 2-3 inches, and a High density ponytail will be 4 or more inches in circumference.
For example, You can have fine hair and have a LOT of it. This is actually the most common client hair type I come across. While you can also have coarse hair that is fairly thin. Typically thinner hair density means there's more visibility to the scalp.
In cosmetology school, my first-phase teacher told us an anecdote that helped me remember the difference between this and hair type.
Imagine that fine hair is compared to an aspen tree. Now imagine that coarse hair is a pine tree. Density refers to how MANY trees there are in the forest. Hair type refers to what KIND of tree they are individually.
Density is determined by a number of factors, namely genetics. Other factors include medications, hormones (A BIG ONE), stress, allergies. and heavy metals in your diet, and scalp care. Hair that is becoming increasingly thin is often due to changes in these factors, especially stress. Hair fall-out can be attributed to many hormonal imbalances and changes, whether that be hormone therapy or hormonal disorders.
Since protein and Keratin are the building blocks to hair, getting enough protein in your diet can greatly improve your hair growth results. I am personally a vegetarian, so I get most of my protein from vegetable proteins.
Hair Structure and Growth Cycle
Hair Structure
In each individual hair strand, the visible part that we see is the cuticle. These are shingle-like in nature, and they are dead cells that form a protective layer around the hair strand. It is also what causes frizz if the cuticle is spread open, rather than laid flat and shiny.
How to tell if your hair is DAMAGED or just DRY
Hair is damaged by a number of things, namely chemical and heat. Truly damaged hair will be obvious in a change of texture and elasticity, especially when the hair is wet. Your hair may be over-processed from chemical processing if you notice it is extremely tangly, or if it snaps when gently stretched. Some damage is caused by things like over-washing, over-brushing (The myth of brushing your hair very often for its health is false) hard water exposure, tension from items such as hair elastics (Use scrunchies or Invisibobble ties instead) and heat.
Dry hair is almost inevitable depending on the climate you live in, your water content wherever you wash your hair, products and heat. Dry hair may feel straw-like, crunchy or tangly. Most everyones hair type will be dry at one point or another. Hair color services that include lightening (bleaching) will dry EVERY hair type out, no matter what, even if bond builder is added. Our hair contains proteins and oils that are necessary for a healthy structure. When lightener or any color with ammonia is added, the opening of the cuticle alone can cause some texture and moisture changes.
Be aware when using products meant for damaged hair, it IS possible to over-proteinize hair. Our hair is only meant to hold a certain degree, more of these products does not always mean MORE healthy hair. Typically, a regimen of damage repair products should only be used one to two weeks, and moisture products should be used the remainder of the time. Healthy oils and fats such as omega 7 are necessary for shiny, strong, healthy hair. See my Instagram reel on oil treatments for more info on oiling hair.
While split ends can be indicative of damage occasionally, the main reason our ends split is
The cortex is inside of the cuticle, which is the thickest part of a hair. It houses the pigment of our hair, as well as the strength and texture. The pigment inside of the cortex is melanin, the same that is found in our skin. The cortex is where all of the hair color magic happens, aside from temporary color which only rests on the cuticle.
Some finer hair types do not have a medulla, the innermost layer of the hair strand, and its primary purpose in humans is unknown. It consists of sparse cells and air bubbles.
Hair goes through a four-stage growth cycle (three depending on who you ask). Each phase of the process happens at different rates for people, depending on genetics and health.
ALL hair sheds. There is a common misconception that only certain hairs shed, or that shedding hair is a sign of bad health, which isn't necessarily true since it is a naturally-occurring process The timing behind when and how often hair sheds is also dependent on those factors. Illness and injury play a part in the factors.
The Anagen phase is the initial growing phase. For most people, this takes between 3-5 years, although some people can have a single hair grow for as long as 7+ years. (People like myself with thyroid and hormone disorders, may see this shortened to less than 3 years.) This phase is when the hair follicle is actively producing and pushing out hair, and continues to do so until they reach the end of their lifespan and fall out, or are cut. At any given time, about 90% of the hairs on our head are in this phase.
The Catagen phase is the transitioning phase of hair, where the follicle shrinks and slows hair growth over a period of about ten days.
The Telogen phase is also known as the resting phase, which typically lasts about three months. Around 10-15% of the hairs on our heads are in this phase at a time. Hair does not grow during this phase, but it also does not fall out initially. Some scientists combine this phase with the last phase, Exogen, as a two part shedding phase.
The Exogen phase is the extended part of the Telogen phase. In this phase, hair is shed from the scalp, usually helped by brushing and shampooing. This is often why we see hair fallout in the shower, which is completely normal for all hair. Some will shed faster or in higher quantities than others. During this phase, it is considered normal to lose 50-100 hairs per day. This phase lasts 2-4 months.
Listed below are some other specific factors and possible indicators for abrupt shedding in the shedding phase.
-Telogen Effluvium is the scientific term for stress-related rapid hair shedding. Each phase can accelerate greatly, causing the shedding to double or triple in amount of hair. Other stress-related hair loss problems are Alopecia Areata, and Trichtotillomania. -
- There is a theory that has come about recently with COVID-19, that indicates that, about 9 weeks post initial infection and fever, (with all high fevers and severe illness this happens) the hair will enter the Exogen phase rapidly, and hair fallout can be more severe. In my case, this did happen, as i'm currently 10 weeks post fever, and recently started rapidly shedding hair way more than normal. This has not been proven, but is a theory. -
-A testosterone by-product known as DHT can attach to hair follicles over time. The intensity of this is usually a genetic factor. It can happen to people of any sex, although it is much more common in those assigned male at birth. In people assigned female at birth, this can manifest after puberty, or in my case, PCOS (Polycystic Ovarian Syndrome). Those with PCOS deal with a much higher rate of natural hormone imbalances and testosterone spikes, that have symptoms and signs all over the body, including excess facial hair, and what some doctors call 'female patterned baldness'. This usually starts at the temples or front hairline. DHT can typically be treated by a number of things, and some over the counter shampoos claim to have properties to fight DHT. These issues are worth researching and speaking to a doctor about.-
Taking supplements in addition to topical or prescription strength medications, can help support the building blocks for healthy hair growth.
Biotin, Collagen, and Turmeric are some of the necessary ingredients to support hair building and strength form the source. You can often find most of these options in gummies and multivitamins for ease of ingestion.
"Miniaturization of the hair follicles leads to a shorter growth phase and eventually to softer, lighter hairs that disappear. In women, DHT production can lead to hair loss conditions called androgenetic alopecia, telogen effluvium, anagen effluvium, and traction alopecia." -WebMD
There are so many shampoos and hair treatments on the market that claim to help with hair density and quality. Doing your research to find the one best for you may take time, but is worth it. Products with this end result are usually worth the money they cost. If anything is surprisingly cheap, it may not hold up to its claims.
-Some brands and products I have had personal success with include-
Vegamour - Growth Serum, Shampoo/Conditioner and Dry Shampoo.
Hers - Thickening shampoo and hair growth gummies.
Nutrafol - Hair growth supplements
Aveda Invati System
Amika 3D Volume system
Olly Hair or Beauty gummies
This concludes my first (and long) blog post. I hope it is informative and not too overwhelming! As always, if you have any questions, need clarification on anything I posted, or want a professional opinion on something hair (not medically) related, let me know!
Love, 💕
Demi
@talking_hairs
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