1. Chapter 11
Properties off the Hair & Scalp

2. Chapter 11
The hair is part of the body and , like every other part, must be cared for and nourished. Just as you replenish body fluids after extended exercising or illness, you must also replenish the needed nutrients for healthy hair. With all the styling tools and chemicals used on the hair today, it is constantly at risk of damage. It is essential that, as a hairdresser, you fully understand the importance of caring for the hair and scalp.

3. Structure of the Hair Shaft
The three main layers of the hair shaft:
cuticle
cortex
medulla

4. Hair Shaft Cuticle outermost layer of hair
consists of a single, overlapping layer of transparent, scale-like cells
like a roof shingles
hair’s primary defense against damage
each individual cuticle is attached to the cortex
imbrications
allows liquids to penetrate

5. Hair Shaft Cortex Middle layer of hair
Fibrous protein core formed by elongated cells containing melanin pigment
90% of hair weight
Hair elasticity
Changes resulting from chemical services occur in the cortex

6. Hair Shaft Medulla Innermost layer Referred to as the pith of the hair
Composed of round cells
Very fine & naturally blonde hair may not even have a medulla
Thick coarse hair & beard hair always contain a medulla

7. Chemical Composition of Hair
Hair is composed of protein that grows from cells originating within the hair follicle
Keratinization
Process during which newly formed cells in the hair mature
They fill up w/ keratin, move upward, lose their molecules, & die
The hair shaft is a nonliving fiber composed of keratinized protein

8. Chemical Composition of Hair
91% protein
Cohns elements
Carbon – 51%
Oxygen – 21%
Hydrogen – 6%
Nitrogen – 17%
Sulfur – 5%
Amino acids
Units of structure in protein

9. Chemical Composition of Hair
Side bonds of cortex
Middle layer of hair is made up of millions of polypeptide chains
Cross-linked like a ladder by three different types of bonds
Hydrogen bonds
Physical side bond that is easily broken by water or heat
They are weak individually, but because there are so many, they account for about 1/3 of the hair’s strength

10. Chemical Composition of Hair
Salt bonds
Physical side bond that is broken by changes in pH.
Easily broken by strong alkaline or acidic solutions
Account for about 1/3 of the hair’s overall strength
Disulfide bonds
Chemical side bond that differs greatly from the physical side bonds

11. Chemical Composition of Hair
Disulfide bonds
Chemical side bond that differs greatly from the physical side bond
Join sulfur atoms of 2 neighboring cysteine amino acids to create cystine
Far fewer than the physical bond, but are stronger
Account for about 1/3 of the hair’s overall strength

12. Hair Pigment
All natural hair color is the result of pigment located within the cortex
Melanin
Tiny grains of pigment in the cortex that give natural color to hair
Eumelanin
Provides brown & black color
Pheomelanin
Provides natural colors from red & ginger to yellow-blonde tones

13. Hair Pigment Natural hair color Gray hair
Is the result of the ratio of eumelanin to pheomelanin, along with the total number & size of pigment granules
Gray hair
Caused by the absence of melanin. It grows in exactly the same way as pigmented hair but without the melanin pigment

14. Haircolor vs. Hair Color
Hair Color ( two words ) refers to the color of hair created by nature.
Haircolor ( one word ) is the term used in the beauty industry to refer to artificial haircoloring products.

15. Wave Pattern & Tendencies
Described as straight
Described as wavy
Described as curly
Described as extremely curly

16. Wave Pattern & Tendencies
Straight hair usually round
Wavy hair usually oval
Curly/extremely curly almost flat

17. Wave Pattern & Tendencies
Asians
Extremely straight hair
Caucasians
Straight to wavy
African-Americans
Extremely curly

18. Summary
Living cells form in the follicle and mature through keratinization
Three layers of the hair is cuticle, cortex and medulla
Hair has different wave patterns
Next lesson – hair analysis