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What is the cuticle?
The hair shaft is made up of three main layers. The tiny inner core is the medulla.
The second layer, which makes up the vast majority, is the cortex. This layer holds the natural pigment, which is made of melanins, similar to skin pigment. When you use permanent hair color, the artificial pigments penetrate down to the cortex to add pigment molecules that stick.
The third layer is a thin outer shell called the cuticle. It is like tiny scales, pointed in a downward direction towards the end of the hair. It protects the hair, and permanent dye must contain a highly alkaline chemical to swell the cuticles open, in order to penetrate the pigment to the cortex. Open cuticles also can lead to tangling when cuticles from adjacent hairs rub against each other. Acids can close the cuticles and make them smooth again. Apple cider vinegar is often used. Conditioners are also formulated for this.
Semi and demi permanent hair dyes, as well as color-depositing conditioners are formulated to stick to the outer layer, without penetrating. This is why the color is not permanent.
Stripping the cuticle.
I came across this interesting info on how the factories strip the hair of the cuticle when processing the hair, so they don't have to deal with tangling.
This scientific paper describes how mixing potassium hydroxide (KoH) solution in 1-butanol will strip the cuticle off the hair, without much damage to the underlying cortex.
http://journal.scconline.org/abstracts/cc1995/cc046n06/p00281-p00290.html
Interestingly, the active ingredient in Nair cream is calcium hydroxide, with potassium thioglycolate. Similar to the KoH/1-b formula, this will also strip the hair, though I believe its main purpose is to destroy the cortex itself.
There is a trade-off with cuticle stripping. In the hair-trade world, Raw or Virgin hair is minimally processed, and does not go through the cuticle bath. Conversely, most factory system hair is likely stripped of the cuticle to prevent tangling. BaldBearded may have more info on the inner workings of factory workflow.
The tradeoff to the hair is some damage, as well as a complete change in its dying properties (the cuticle is naturally the hair component that permanent hair color is formulated to seep through very slowly. This is a big reason why system hair colors way faster). The cuticle layer is a natural layer of protection for the hair.
You can easily check your strands for cuticles. Pinch the hair in your fingers and first slide down the hair, then slide up. If you feel a lot of resistance in one direction, then the cuticle is intact and the root is towards the direction of resistance.
The hair shaft is made up of three main layers. The tiny inner core is the medulla.
The second layer, which makes up the vast majority, is the cortex. This layer holds the natural pigment, which is made of melanins, similar to skin pigment. When you use permanent hair color, the artificial pigments penetrate down to the cortex to add pigment molecules that stick.
The third layer is a thin outer shell called the cuticle. It is like tiny scales, pointed in a downward direction towards the end of the hair. It protects the hair, and permanent dye must contain a highly alkaline chemical to swell the cuticles open, in order to penetrate the pigment to the cortex. Open cuticles also can lead to tangling when cuticles from adjacent hairs rub against each other. Acids can close the cuticles and make them smooth again. Apple cider vinegar is often used. Conditioners are also formulated for this.
Semi and demi permanent hair dyes, as well as color-depositing conditioners are formulated to stick to the outer layer, without penetrating. This is why the color is not permanent.
Stripping the cuticle.
I came across this interesting info on how the factories strip the hair of the cuticle when processing the hair, so they don't have to deal with tangling.
This scientific paper describes how mixing potassium hydroxide (KoH) solution in 1-butanol will strip the cuticle off the hair, without much damage to the underlying cortex.
http://journal.scconline.org/abstracts/cc1995/cc046n06/p00281-p00290.html
Interestingly, the active ingredient in Nair cream is calcium hydroxide, with potassium thioglycolate. Similar to the KoH/1-b formula, this will also strip the hair, though I believe its main purpose is to destroy the cortex itself.
There is a trade-off with cuticle stripping. In the hair-trade world, Raw or Virgin hair is minimally processed, and does not go through the cuticle bath. Conversely, most factory system hair is likely stripped of the cuticle to prevent tangling. BaldBearded may have more info on the inner workings of factory workflow.
The tradeoff to the hair is some damage, as well as a complete change in its dying properties (the cuticle is naturally the hair component that permanent hair color is formulated to seep through very slowly. This is a big reason why system hair colors way faster). The cuticle layer is a natural layer of protection for the hair.
You can easily check your strands for cuticles. Pinch the hair in your fingers and first slide down the hair, then slide up. If you feel a lot of resistance in one direction, then the cuticle is intact and the root is towards the direction of resistance.