Sebum was supposed to keep our fur nicely water-repellent to keep us from being soaked, cold and get sick. Its real purpose can still be observed in furry animals, maybe especially sheep. I think everyone knows just how “greasy” a sheep’s fur feels. That is pure lanolin.
With our lack of fur, sebum serves very little purpose today. I guess “producing sebum” didn’t give us enough of a disadvantage to be bred out of the population.
Today it still serves a purpose in keeping the pH value in the scalp at a healthy level, providing living conditions for our benign bacteria population and keeping the skin lubricated so it wont crack and be damaged.
Sebum is produced in our bodies’ sebaceous glands, which can be found everywhere on the body except the bottom of the feet and the palm of the hands. It is a mixture of triglycerides, cholesterol, wax and proteins. Sebum itself has no smell, but when bacteria breaks it down it can result in a bad odour.
Over my years on the longhair circuit I have often encountered the idea that your scalp produces two kinds of sebum. I have yet to find any official books or recourses confirming this, but it seems to match my observations from myself and other longhairs.
They are often described as a “liquid” sebum and a “waxy” sebum:
The “liquid” sebum is what makes your hair greasy or oily and weighs it down. Some people also describe a change in colour as hair seems darker where the liquid sebum coats the hair. Some even describe being able to see the “border” on their hair of how far down the liquid sebum has come. There seems to be some discussion as to whether this one penetrates the hair strands or not. It does however coat the hair with its greasy oil and may protect it like a leave in conditioner. This type of sebum is chemically very close to jojoba oil (Jojoba oil is coincidentally a wax that turns liquid and behaves like an oil in room temperature, not an actual oil) which also doesn’t penetrate the hair strand but coats the surface.
The “waxy” sebum is what people often refer to as “scalp gunk”. It forms as a white, dandruff-like coating of the scalp. Most people seem to discover this when they unconsciously scratch their scalp and find a white, waxy layer under their nails. This should not be confused with dandruff which is caused by excess shedding of dead skin cells from the scalp. Neither should it be confused with product build up. This form of sebum doesn’t penetrate the hair strand. It also doesn’t move down the hair strands unless manipulated, but only collects at scalp level. When manipulated it will “flake off” in dandruff-like flakes or “roll off” like when removing a peeling mask.
I have tried to get an answer to whether the scalp also carries two different kinds of sebum producing glands, but haven’t gotten a clear answer so far. There are two different sebum-producing glands on the human body, but I’m not sure if it extends to the scalp as well.
A gland that release sebum is called a sebaceous gland. These are also classified as being “exocrine”, meaning that their active cells release their product to a surface, in this case the skin. The opposite, “endocrine” means that the gland releases its product to the blood stream.One kind is connected to the insides of a hair follicle, meaning it releases the sebum to the insides of the tube where hair emerges from. You may be able to empty some of the content of this one to make washes more cleansing.
The other kind connects directly to the surface of the skin (Epidermis) and releases the sebum to the surface of the skin. It is not connected to a hair or follicle.
Maybe the two glands carry their own ratio of liquid to waxy sebum?
No matter what, every individual has their own ratio of liquid to waxy sebum. Some people suffer mostly from greasy hair and some have a lot of scalp gunk. Some people produce very little of both and have dry scalp.
The production(s) of sebum can be provoked by harsh chemicals, heat and too much manipulation. A lot of longhairs have experienced that switching to gentler methods for cleaning will result in less sebum production. Working with the scalp instead of trying to dry it out to “clean” it will make the scalp ease down on the sebum production because it doesn’t have to work so hard to maintain its natural state.
Personally, when I tried to switch from shampooing 3 times a week to full-time CO, I hit a plateau where I couldn’t get under using shampoo once a week. I allowed my scalp to go completely greasy and “stretch” it as far as I could stand it. I had to give up after 9 days and wash a head of hair that was more grease than hair. But it seemed to have “broken” the plateau and I was able to go full CO wash after that (Since then I have used shampoo maybe once a year on average)
So what are the hair friendly ways to remove sebum?
Shampoo of course will remove it, but most longhairs will avoid shampoo if other methods are possible.
There are differences in how much work the two kinds of sebum take to remove.
The liquid sebum is the easiest to remove. CO or herbs seems to do it for most people. It can also be reduced with cold or warm WO washing, not hot since hot water will provoke more sebum production. Brushing a bit before washing will increase the effect from any form of washing because the sebum is brushed out and distributed over a larger surface and less concentrated.
Scritching is a popular method for removing the waxy sebum. Otherwise the waxy sebum can require detergents or lots or rinsing in combination with scrubbing. Sugar scrubs and herbs used for exfoliation are good too. I like to incorporate a good scalp massage in my cassia treatments. The grainy herbs are good for exfoliating.
To quote from Hair Geek Dictionary:
Scritching: Most common term used for mechanically cleaning the scalp. Using fingertips, brush, comb or massage devices to “scratch” sebum and dead skin cells out of the scalp.
This is not to be confused with massage. Massage is said to relieve the discomfort from a gunky scalp, but it doesn’t remove a lot of it.
Brushing also works to loosen up the gunk and free it from the scalp. Of course this doesn’t mean you should brush your hair 100 strokes per day like the old wives tale says.
However, no matter your method, there is a limit to how long you should manipulate your scalp to get rid of sebum. Too much manipulation provokes the scalp into releasing more sebum. If your scalp gets a tingly feeling, you are probably at the limit to how much more you should stimulate it. Massaging and manipulating your scalp to increase blood flow and hair growth is different. With that, you want the tingly, “activated” feeling.
For both kinds of sebum, oil will always help loosen or dissolve it. Oil dissolves oil. This is the same principle as the Oil Cleansing Method for skin works by.
Personally I use scritching as part of a treatment plan.
My tools for scritching:
- The day before I want to CO wash, I take my hair down and comb it with a widetooth comb.
- I scritch the scalp using a fine tooth comb in a narrow zig-zag pattern.
- I brush the scalp with my ancient, super hard bristled brush. (The only brush I ever feel can get “through” to my scalp)
- I use the scalp massager thing (What is this thing called?)
- Then I fill the bathtub about halfway and do a mermaid soak. Lying back in the tub is a good position to use your finger to massage and scritch the scalp.
- I finish with a rinse.
- Then I do a Nodosaurus overnight.
- Next morning I rinse out the length and CO wash the scalp.