Hair Care Products l Shampoos l Conditioners l

Hair Care Products l Shampoos l Conditioners l “ 2 in 1” shampoos l Hair sprays 1

Hair Care Products (con(. l Hair gels l Perming solutions l Hair dyes l etc. l General remarks about product development 2

Hair Structure Hair follicle • a tiny cup-shaped pit burried deep in the • fat of the scalp • follicle is the point from which the hair grows • well supplied with minute blood vessels • temperature is normal body temperature 3

Hair Structure (con. ) • temperature is not affected by cold or hot water • the rate of growth depends on the amount of natural light : growing a little faster in winter when the days are short 4

Hair follicle Hair bulb Hair shaft Hair bulb - lines in side the hair follicle - is a structure of actively growing cells - produce a long fine cylinder of hair - new cells are continuously produced in the lower part of the bulb 5

)a) Longitudinal section of a hair within its follicle. )b) Enlarged longitudinal section of a hair. 6

) c) Enlarged longitudinal view of the expanded hair bulb of the follicle which encloses the matrix, actively dividing epithelial cells that produce the hair. 7

)d) Cross section of a hair and hair follicle. 8

)e) Photomicrograph of scalp tissue showing numerous hair follicles (24 X. ( 9

The Hair Shaft • can be seen above the scalp • consist mainly of dead cell Keratin + binding material + small amount of water • terminal hairs are lubricated by natural oil (sebum) produced by sebaceous glands • high level of hormones (androgens) high level of sebum 10

Nature of cuticle • scales growing over the youngest part (closet to the scalp) are smooth and unbroken further along the hair have been damaged by cosmetic treatments and by mistreatment : (overenergetic brushing) 11

Nature of cuticle (con. ) • little by little, they may break away : “weathering” • healthy cuticle is more than just a protective layer • intact cuticle cells are smooth, glossy, and reflect light from their surface (black hair reflects less light than blond hair) 12

The cuticle scale on a normal hair )electronmicrograph( 13

A perfect hair seen under the electron microscope Another normal hair - but this came from one of our nearest relatives an orangutan ! 14

Hair shape • keratin chains link by : disulphide bond and hydrogen bonds • disulphide bonds can be changed by chemical methods : perming and relaxing permanent 15

Hair shape (con. ) • hydrogen bonds can be easily broken apart whenever the hair is wetted and form again as it dries • when they break the shape of hair changes • wet hair is wound on the roller, the dried hair keep the roller shape temporary 16

Hair growth cycle • individual hair form inside a hair bulb deep in hair • follicle is tiny but powerful factory • each hair grows during many years • shampooed, conditioned, cut, blown dry, exposal to the sun and wind, colored, bleached, permed none of these affected the hair growth 17

Hair growth cycle (con. ) • the hair spontaneously falls out • the follicle rests for a little while and starts to produce a new hair 18

Stage of the hair cycle • anagen : the growing phase (~1000 days) • catagen : the intermediate phase (~10 days) • telogen : the shedding phase (~100 days) 19

Anagen (the growing phase) • last between 3 -7 years without interruption • roughly 1 cm/month > 1 meter • faster rate in winter than summer • melanin is made in hair bulb throughout this phase 20

Anagen (con(. • less pigment is made in older people, hair cycle becomes shorter • follicles gradually give up producing long, strong hair : • hairs become thinner and shorter of the hair thinning degree of baldness 21

Catagen (the intermediate phase) • short resting phase : 2 -4 weeks • no pigment is made • follicles stop producing hair • the base of follicle moves upwards towards the surface of the skin 22

Telogen (the shedding phase) • last for 3 -4 months • new hair begin to grow from the hair follicle • as it grow s upwards the old hair will be shed naturally or easily be pulled out 23

Telogen (con. ) • at anytime around one in ten of the follicles at individual’s head is in the shedding phase • shedding is part of normal process of the replacement of old hair with new hair • new hair emerges from the same opening as the old one 24

The hair follicle cycle 25

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Hair Color Pigmentation Melanin : - produced by melanocytes at growing phase (anagen) - spread out throughout the cortex, the more near outer edge lie along the amino acid chains - does not protect the harmful effect from sunlight - is found in 2 forms 27

Pigmentation (con. ) • Eumelanin : dark pigmented which predominates in black and brunette hair/oval shape • Phaeomelain : lighter pigment, found in red and blond hair/smaller, partly oval and partly rod- shape 28

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Physical properties of hair • • • Strength Elasticity Static electricity Moisture content Porosity Texture 30

Hair strength • a single hair can support a load of about 100 gm • keratin protein of the cortex responsible for the • hair strength • keratin is a protein chains contain high concentration of an amino acid called “cystine” • matrix contains high level of cystine 31

Hair strength (con. ) • each cystine unit contains 2 cysteine amino acids in different chain • the chains are linked by two sulphur atoms, forming a very strong chemical bond “disulphide linkage” • many disulphide bonds form down the length of the keratin chains 32

Chemical bonds within the hair maintain its shape 33

Elasticity • one of the most important properties • can resist forces that could change its shape, volume and length • lest spring back to its original form without damage • wet hair can increase the length up to 30% and return to original length when it is dried 34

Elasticity (con. ) • elasticity of hair depends on the long keratin fibers in the cortex • chemical treatment can alter the cortex and change the hair elasticity 35

Elasticity (con. ) • poor elasticity : - stretch only to a limited extent - will break easily - cannot be permed satisfactorily • natural sunlight and artificial UV light damage chemicals of hair and its elasticity 36

Static electricity • rubbing drug hair / brushing / combing builds up static electric charge • the charges tend to push each other apart • charged hair never lie smooth against each other “ fly away ” hair • stands out from the head 37

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Moisture content : Heat and humidity • more moisture • less static electricity • collapse Heat and dryness • less moisture • more static electricity • more volume 39

Moisture content (con. ) - wet hair swell cortex / lift cuticle scales - hair surface temporaly loses its smoothness - wet hair more friction matting and tangles (over vigorous shampoo) 40

Porosity Normal hair • cuticle covering cortex is intact : almost water proof (very little water can go in and out) • shampoos do not damage the cuticle • treating the hair (permed or tinted) 41

Porosity (con. ) • temperature / applying an alkaline lotion separate the scale • allowing chemicals to go inside • after processing scales close up 42

Texture • the larger the hair diameter the coarser it will feel • different people’s hair naturally feel different soft / hard / silky / wiry • effected by degree of weathering of hair 43

Texture (con. ) Texture is affected by what has been put on it : - spray : makes different feeling - conditioner : feel soft and smooth -conditioner with silicone : protect the hair cuticle - damage to cuticle : alter the hair texture 44

Chemistry of Hair • Keratinization process in the follicle keratin + water soluble substances : pentose, phenols, uric acid, glycogen, glutamic acid, valine, leucine 45

Chemistry of Hair (con(. • Keratin is composed of amino acid • 18 out of 25 normal amino acids are found in keratin 46

Chemistry of Hair (con(. • Organization of hair protein sets up by bonding in 3 ways: I Formation of H-bonds between parallel peptide chains 47

Chemistry of Hair (con(. II Formaton of salt linkage between acidie and basic side chain 48

Chemistry of Hair (con(. III Formates of disulphide linkages • amino acid contains two amino and two carlygl groups link together by a disulphide bond 49

Structure for a- keratin 50