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Development Team
Principal Investigator
Dr. Vijaya Khader
Former Dean, Acharya N G Ranga Agricultural University Prof. Farhan J Ahmad
Jamia Hamdard, New Delhi
Paper Coordinator Dr. Javed Ali
Jamia Hamdard, New Delhi
Content Writer Dr. Sanjula Baboota
Jamia Hamdard, New Delhi
Content Reviewer Prof. (Mrs.) Kamla Pathak
Professor, Pharmaceutics
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CONTENTS
1. Introduction to Hair
1.1 Composition of Human hair 1.2 Structure of Hair
2. Hair care products 2.1 Shampoo
2.2 Requirements of shampoo 2.3 Shampoo ingredients
2.4 Cleansing action of shampoo 2.5 Classification of shampoo 2.6 Evaluation of shampoo 2.7 Packaging of shampoos
2.8 Indian Bureau of standards for shampoo 3. Hair creams
4. Hair conditioners 5. Summary
6. Suggested readings
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1. Introduction to Hair
Hair are simple thread like structures (about 50-100 µm in diameter) and are found over our entire body and serves as a protective layer. They help in regulating the body temperature, collects sweat, protects from the harmful effects of UV radiations and act as a barrier to the entry of foreign objects and other damaging particles. More specifically the hair on human head provides protection to the scalp from the sun rays and also helps in holding the body heat.
1.1 Composition of Human hair
More than 90 percent of the hair is made up of long chains of amino acids. These amino acids are joined to each other with peptide bonds and forms polypeptide which further intertwined around each other in a helix shape. The composition of a normal hair is 45.2 % carbon, 27.9% oxygen, 6.6% hydrogen, 15.1% nitrogen and 5.2% sulphur. Among all proteins, keratin roughly constitutes 65–95% of the total volume, remaining matter of hair is filled with water and lipids. The keratin found in hair is hard and tough in nature which does not get dissolved in water. It is made up of eighteen amino acids. The most abundant of these amino acids is cystine which provides hair strength.
The colour of the hair is decided by the amount of melanin present in the hair which is found in cortex. Melanin is produced in hair by a group of specialized cells called melanocytes which are present near hair bulb. These cells form bundles of a pigment protein complex called melanosomes. The percentage, type and distribution of the melanosomes in the hair are responsible for the colour of the hair. There are two types of melanin Eumelanin and Phaeomelanin. The type of melanin present in a person's hair is inherited. Eumelanin is more commonly found and gives various shades of brown/black colour to the hair. Phaeomelanin is red in color and gives various shades of red to the hair.
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There are three determinants that decide the hair colour a. The thickness of hair
b. The total number and size of pigment granules c. The ratio of eumelanin to phaeomelamin Grey Hair
The number of pigment granules present in hair begin to decline naturally as a person ages. A normal healthy person begins to grey between the age of twenty-eight and forty years. The possible reason for this greying is that the melanocytes begin to decrease and starts producing less melanin. However, this is a part of the natural aging process in humans. But some serious illnesses or emotional conditions may also lead to greying of hair.
1.2 Structure of Hair
A single strand of hair basically consist of two parts –one that lies above the scalp and is known as the hair shaft and the other one which lies beneath the scalp and is known as the hair root.
Hair root is embedded in the hair follicle.
a) Hair follicle
This is the living part of human hair. It is also known as hair production unit. It's a stocking-like structure that consist of various cells and connective tissue. The base of hair follicle has a bulb like structure called as dermal papilla. This part is filled with tiny blood vessels that provide nutrients and oxygen necessary for nourishing the hair growth. Hair follicle also consist of germinal matrix. In germinal matrix new hair are produced.
b) Hair bulb
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The hair bulb forms the base of the hair follicle and surrounds the papilla and germinal matrix. It consists of several types of stem cells that divide and grow very fast to build the hair shaft. The cells in the bulb are well nourished with blood vessels and receive hormones that modify hair growth and structure at different phases of life.
c) Hair shaft
The hair shaft is the outermost part of the hair which is visible (figure 1). It consists of non-living cells and is made up of three layers which contains a tough protein, keratin. Medulla is the innermost layer of the hair shaft. This is followed by the middle layer cortex, which constitutes majority of the hair shaft. Both medulla and cortex contain pigmenting elements which produce melanin and impart color to the hair. The outermost layer of the hair shaft is cuticle, which is formed of tightly packed scales in an overlapping structure that resembles roof shingles.
Figure 1: Anatomy of Hair
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2. Hair care products
Hair care products include shampoos and conditioners which aid in the maintenance and grooming process. The major function of shampoos is to clean the hair, scalp and other greasy residues, whereas hair conditioners help to repair hair damage and make the hair smoother, softer, shiner, manageable and easy to comb.
2.1 Shampoo
A shampoo can be defined as a detergent solution which is modified by additives to make it easier to apply and to safeguard against deterioration of the hair condition after the shampoo has been rinsed away. Shampoos are primarily used to clean the hair and scalp. However, shampoos serve many secondary functions which include:
Help in the treatment of dandruff.
Help in reduction of scalp irritation.
Aid in conditioning.
Aid in moisturizing.
In addition to above functions shampoos also improve various scalp conditions such as:
• Restoration of alkali neutralization ability (pH)
• Dryness
• Seborrhea
• Scalp bacteria (Malassezia spp., Propionibacterium spp.)
• Enzyme activity of the scalp 2.2 Requirements of shampoo
There are many requirements which need to be kept in mind while formulating a shampoo. These include:
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1. The shampoo should be able to remove sebum.
2. The shampoo should be able to produce sufficient foam.
3. It should be non-irritating to scalp.
4. The shampoo should be non-damaging to eye.
2.3 Shampoo ingredients
There are various ingredients used in shampoo (as listed in table 1).
2.3.1 Cleansing agents: Surfactants are the most important ingredient in the shampoo formulation as they aid in the removal of dirt and greasy residue from the scalp. Surfactants have very good lathering capabilities and rinse off very easily from the hair. Surfactant molecules aid in cleaning hair by encircling the greasy matter on the hair surface. The non-polar end which is soluble in greasy matter buries itself in the grease, which leaves the polar head to face outward with a negative charge. Since the hair fibers are also negatively charged, the two negative charges repel each other. Therefore, the greasy matter is easily removed from the hair surface and rinsed off. Among various surfactants, anionic surfactants are known to be good in cleaning.
These include various salts of sulphates and sulfonates. In addition shampoos may contain several surfactants, generally up to four, which clean the hair in different manner depending on the hair type of the individual. The non-ionic surfactants are used in the shampoos as a modifier of foam characteristics, especially foam quantity and consistency.
2.3.2 Thickening agents: The viscosity of shampoo needs to be good as this is necessary for easy application into the hair. The right blend of different additives is required so that the shampoo is not too thin and not too thick. Cellulose derivatives can be used as thickening agent.
Polymers of acrylic acid and vinyl pyrrolidone have been employed to enhance the viscosity of shampoos. Glucose esters can cause difficulties due to their viscosity but they enrich the foam characteristics and reduce irritation.
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2.3.3 Aesthetic additives: Shampoos additives do not affect the hair washing process directly but they give the shampoo formulation an aesthetic appearance and desired consistency. These include additives which enhance the appearance, colour, and smell of the mixture. These additives are used to improve the hair condition so that the customer can get a good feel of the shampoo itself. Some additives can also control the acidity of the shampoo by obtaining a goal pH level, typically around a value of 4. Examples of such additives include polyquaterniums, silicone additives, proteins and amino acids, ceramides, panthenol, glutamic acid derivatives.
2.3.4 Conditioning agents: Hair get damaged due to several mechanical stresses such as combing, brushing or due to chemical treatments such as permanent hair waving and colouring.
Conditioning agents are added in shampoo formulations so that natural healthy condition of shampoos is restored. Many shampoos also contain conditioning agents which serve the same roles as full conditioners. Examples of conditioning agents include fatty substances such as vegetable oils, wax, lecithin and lanolin derivatives, protein hydrolysates (collagen, silk, animal proteins), quaternary ammonium compounds, silicones and dimethiconecolpolyols. These agents greatly improve combing and antistatic properties when used in low concentrations (0.1-0.5%).
2.3.5 Preservatives: Preservatives are added to shampoos to protect them from bacterial contamination and any kind of decomposition. Examples of preservatives include:
Organic acids and their derivatives, e.g., parahydroxybenzoic acid ester, salicylic and sorbic acid
Parbens: Methylparaben
Formaldehyde releasers, e.g., 1,3-Dimethylol-5,5-dimethylhydantoin.
2.3.6 Pearlizers and opacifiers: These agents are used to give the shampoo a creamy appearance which is helpful to people with dry or damaged hair. A pearlized effect can be obatined by glycol distearate, but this requires a hot process and inconsistencies are inevitable. It
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is more usual to use prepared pearl concentrates. Latex opacifiers do not have the sparkle of the pearlizers, but are used to obtain a flat opaque appearance.
2.3.7 Medically active ingredients: Various medically active substances can be used for people suffering from dandruff and other hair and scalp disorders. These ingredients aim to cure or control these conditions. For the treatment of dandruff, zinc pyrithione is commonly used shampoo additive. For hair loss issues, panthenol is commonly added to shampoos to aid in hair growth and moisture content
Table 1: Components of common shampoos and their functions
Shampoo component Function Example
Cleansing agent (surfactants)
Remove dirt and grease from scalp; produce lather to trap greasy and oily matter from hair and prevent redeposition
Anionic surfactants:
Sulphates and sulfonates Conditioning agents Condition and smoothen the
hair
Dimethiconecolpolyols Thickening agents Control viscosity of shampoo Hydrocolloids such as
polyvinyl alcohol or cellulose derivatives, polymers of acrylic acid and vinyl pyrrolidone, glucose esters
Preservatives Prevent from degradation and contamination
Parahydroxybenzoic acid ester, salicylic and sorbic acid, methylparaben
Aesthetic additives Enhance colour, scent, and luminescence of shampoo
Polyquaterniums, silicone additives, proteins and amino acids, ceramides, panthenol, glutamic acid derivatives.
Pearlizers and opacifiers Give creamy appearance to shampoo, used for dry and damaged hair
Glycol distearate
Medically active Treat dandruff and other scalp Zinc pyrithione, selenium
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ingredients problems sulphide, salicylic acid
2.4 Cleansing action of shampoo
The recent underlying science of cleaning is based on three vital components of hair soil:
1. Sebum
2. Dust from atmosphere 3. Proteinous matter
The shampoos clean hair by removing all these components of hair soil. They do so by various mechanism. The process of removal of lipid soil from hair is based on the principal of detergency which involves the role of surfactants to remove the debris from the hair. This is explained by the figure 2.
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Figure 2: The cleansing action of shampoo
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In the first stage the detergent micelles comes in contact with the lipid part (sebum) and lead to the formation of lipid-surfactant co-micelles. These co-micelles then detaches and floats away into the bulk aqueous solution leaving the surface of hair and scalp clean.
The performance of shampoo is assessed by formation of foam or lather. There are three parameters to evaluate this:
1. Rapidity with which the foam is formed.
2. Peak volume of the foam.
3. Consistency of the lather (high consistency is judged as being creamy).
2.5 Classification of Shampoos
On the basis of appearance, shampoos can be broadly classified as clear shampoos, gel shampoos, paste shampoos, powder shampoos and pressurised shampoos (also known as mouse).
On the basis of functions they can be divided as conditioning shampoos and anti dandruff shampoos.
2.5.1. Powder Shampoo or Dry Shampoo
This is a specific type of shampoo which is used to adsorb dirt and oil from the hair and scalp. It is either applied in spray form or in the form of loose powder. Dry/powder shampoo has to be brushed throughout the hair to distribute the powder and to get rid of any white residue.
Sometimes colours are present in dry shampoo. Dry shampoo is also found to be helpful to build body and texture in the hair.
An example of powder shampoo
Formula %w/w Henna powder 5.0 Soap powder 50.0
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Sodium carbonate 22.5 Potassium carbonate 7.5 Borax 15 Perfume, preservatives, colour q.s Procedure:
Powder all the ingredients and sieve.
All ingredients are mixed together in pestle and mortar in increasing order.
The prepared shampoo is then labelled and dispensed.
2.5.2 Cream/ Lotion Shampoo
These are semisolid preparations used to cleanse the hair and are generally emulsions. These shampoo are generally white in colour but coloured variants are available.
An example of lotion shampoo
Formula %w/w Monoeth, lauryl sulfate (30%) 45.0 Sodium chloride 3.5 Demineralized water 51.5 Perfume, preservatives, colour q.s Procedure:
Monoethlauryl sulfate, perfume, preservatives and demineralized water are mixed together with gentle stirring to minimize frothing.
Sodium chloride is added to the above mixture with vigorous shaking and the mixture is left for settling.
The shampoo is then labelled and dispensed.
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An example of cream shampoo
Formula %w/w
Sodium lauryl sulfate (30%) 30.0 Cetyl alcohol 7.0 Deionized water 63.0 Perfume, preservatives, colour q.s Procedure:
Sodium lauryl sulfate, perfume, preservatives and deionized water are mixed together with gentle stirring to minimize frothing.
Weighed amount of cetyl alcohol is added to the above mixture with vigorous shaking and mixture is left for settling.
The shampoo is then labelled and dispensed.
An example of clear gel shampoo
Formula %w/w
Sodium lauryl sulfate (28%) 35.0 Cocodiethanolamide 1.5 Methylcellulose 8.0 Deionized water 55.5 Perfume, preservatives, colour q.s Procedure:
Sodium lauryl sulfate, cocodiethanolamide, perfume and preservatives are mixed together with gentle stirring to minimize frothing.
Viscosity modifier agent, methylcellulose is added to the above mixture with vigorous shaking and mixture is left for settling.
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The shampoo is then labelled and dispensed.
2.5.3 Anti-dandruff shampoo
These shampoos generally help in overcoming the problem of dandruff in the scalp and thereby cleanse the scalp. Now –a-days a number of shampoo are present in the market which serve this purpose. These shampoos contain antidandruff agents such as zinc pyrithione, selenium sulphide and salicylic acid.
An example of anti-dandruff shampoo
Formula %w/w
Selenium sulfide 2.5 Bentonite 5.0 Sodium lauryl sulfate (30%) 35.0 Demineralized water 57.5 Perfume, preservatives, color q.s Procedure:
Sodium lauryl sulfate, selenium sulfide, perfume, preservatives and demineralized water are mixed together with gentle stirring to minimize frothing.
Weighed amount of bentonite is added to the above mixture with vigorous shaking and mixture is left for settling.
The shampoo is then labelled and dispensed.
2.5.4. Conditioning shampoo
These types of shampoos have gained considerable importance in recent years. These newer formulations are aimed to wash and condition the hair and scalp in one operation, leaving behind the hair manageable, easier to comb, lustrous and soft. These type of shampoos contain specific
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materials such as silicones and polyquaterniums. These type of shampoos are quite suitable for dry hairs.
An example of conditioning shampoo
Formula %w/w
Triethanolamine lauryl sulfate (33%) 25.0 Cocodiethanolamide 2.0 Lauryl aminopropionic acid 7.5 Lactic acid to pH 4.5-5.0 Demineralized water 65.0 Perfume, preservatives, color q.s This formulation has pH value near to the isoelectric point of hair to improve the condition of hair.
Procedure:
Triethanolamine lauryl sulfate, cocodiethanolamide, perfume, preservatives and demineralized water are mixed together with gentle stirring to minimize frothing.
The weighed amount of lauryl aminopropionic acid and lactic acid are added to the above mixture to adjust the pH of the formulation and mixture is left for settling.
The shampoo is then labelled and dispensed.
An example of conditioning shampoo with silicone gel
Formula %w/w
Sodium lauryl sulfate (30%) 55.0 Cocodiethanolamide 2.5 Dimethiconecopolyol 5.0 N-alkyl betaine q.s.
Demineralized water 65.0
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Citric acid to pH 6.5-7.0 Perfume, preservatives, colour q.s Procedure:
Sodium lauryl sulfate, cocodiethanolamide, dimethiconecopolyol perfume, preservatives and demineralized water are mixed together with gentle
stirring to minimize frothing.
Viscosity modifier agent, N-alkyl betaine is added to the above mixture with vigorous shaking and mixture is left for settling.
Shampoo is then labelled and dispensed.
2.5.5. Premium shampoo
Premium shampoos have entered in the market in the recent years. These types of shampoos are aimed to thicken, balance the pH and to add volume to the hair. This kind of shampoos make use of higher surfactant levels and they also contain variety of conditioning and moisturizing ingredients, such as modified silicones, wheat proteins, panthenol and natural extracts.
2.5.6. Baby shampoo
These types of shampoos are formulated with extreme care and should not cause any kind of irritation when applied. In this type of shampoo, non-ionic surfactants such as polysorbate 20 are used. These type of surfactants do not contribute to the foaming capability but they help in reducing the irritancy potential of the shampoo.
Also pH balance is essential in this type of shampoo to avoid any kind of irritation.
An example of baby shampoo
Formula %w/w
Magnesium lauryl sulfate (27.5%) 11.0
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Cocamidopropylbetaine (30%) 5.0 Polysorbate 20 1.0 PEG 600 3.5 Citric acid to pH 6.0 Deionized water 84.0 Perfume, preservatives, color q.s Procedure:
Polysorbate 20, PEG 400, magnesium lauryl sulfate, perfume, preservatives and and demineralized water are mixed together with gentle stirring to minimize
frothing.
Weighed amount of cocamidopropylbetaine is added to the above mixture with vigorous shaking and mixture is left for settling.
Citric acid is added to the mixture to adjust the pH of shampoo.
The shampoo is then labelled and dispensed.
2.6. Evaluation of Shampoo
To assure the quality of shampoos, specific tests for shampoo formulations are performed.
2.6.1. Physical appearance and visual inspection: The shampoos are first evaluated for various physical parameters such as clarity, foam producing capability and fluidity.
2.6.2. Determination of pH: pH is an important parameter while formulating shampoo. The pH is determined by making 10% shampoo solution in distilled water and then measuring pH using pH meter at room temperature (25°C). The acceptable limit for pH is between 4-9.
2.6.3. Determination of percent of solid contents: This test is carried out to determine any solid matter present in the shampoo. For this purpose, a clean dry evaporating dish is used. To
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the evaporating dish, 4 grams of shampoo is added. Then the combined weight of dish and shampoo is determined. The dish is placed on the hot plate. The evaporating dish is reweighed and weight of the solid matter present in shampoo (solids) after drying is calculated. The official limit for total solid contents is not more than 10 %.
2.6.4. Rheological evaluations: Viscosity is important while formulating shampoo. Too high and too low viscosity is not desired as it creates difficulty during use of shampoo. The viscosity of the shampoos can be determined using Brookfield Viscometer. Spindle speed is kept between 0.3-10 rpm and temperature is kept at 25˚C during the study.
2.6.5. Dirt dispersion: Dispersion of dirt is determined by adding two drops of shampoo in a large test tube that is filled previously with 10 ml of distilled water. To this test tube, 1 drop of Indian ink is added and shaken for ten times. In the form produced, the content of ink is recorded as heavy, moderate, light or none.
2.6.6. Cleaning action: It is very important to evaluate the cleansing action of the shampoo. For this purpose, hair tresses are used. These tresses are first washed properly with 5% sodium lauryl sulphate solution which are then dried and cut to obtain 3 gm weight. The sebum composition is chosen so that it mimics with the actual sebum present in hair. Three grams of hair swatch are suspended in 10% sebum solution in hexane for 15 minutes with stirring at regular intervals.
Afterwards, the swatch is removed and solvent is evaporated. The sample is then weighed to calculate the sebum load. The swatch is then divided into two parts: one for shampoo treatment and other for control. The control sample is left untreated. The test sample is treated with 0.1 ml of 10% shampoo solution. After shampoo treatment the hair are removed and dried properly using hair dryer to obtain uniform moisture content.
The sebum that still remains in hair strands after shampoo treatment is extracted with 10 ml of hexane in a stoppered flask for 30 minutes. The hexane solution is evaporated to dryness. The
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sebum obtained from the test and control sample are weighed. Content of sebum cleaned is determined as:
Detergency = 100 – (S× 100/A)
Where A and S are the sebum weight in the control and test sample, respectively.
2.6.7. Surface tension measurement: Stalagmometer is used to determine surface tension. A 10% shampoo solution is used. The following equation is used to calculate surface tension:
𝑇2 = (𝐶3 − 𝐶1)𝑛1 (𝐶2 − 𝐶1)𝑛2 × 𝑇1
where, C1 is weight of empty beaker.
C2 is weight of beaker with distilled water.
C3 is Weight of beaker with shampoo solution.
n1 and n2 are number of drops of distilled water and shampoo solution, respectively.
T1 and T2 are the surface tension of distilled water and shampoo solution, respectively.
2.6.8. Foaming ability and foam stability: Foaming ability of the shampoo can be determined by the cylinder shake method. In this method 50 ml of the 2% shampoo solution is placed into a 250 ml graduated cylinder. The cylinder is then covered with hand and shaken for 10 times.
Immediately after shaking the volume of foam at 1 minute intervals for 4 minutes is recorded.
The official BIS limit for foam height is 150 mm.
2.6.9. Skin sensitization test: Three groups of animals are used in which one group serves as normal which do not receive any treatment. The other group is treated with shampoo formulation. Group three animals are treated with 0.8% v/v aqueous solution of formalin which is used as a standard irritant. According to the observation grades are given in table 2.
Table 2: Grades for test Scale Observation
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0 None
1 Slight 2 Well defined 3 Moderate 4 Scar formation
2.6.10. Eye irritation test: For eye irritation test, albino rats are preferred. About 1% of the shampoo solutions is instilled dropwise into the eyes of six albino rabbits. Further, the eyes are observed for any irritation/or damage and recorded at definite intervals over a gap of 4 seconds.
2.6.11. Surface characterization: Surface morphology of the hair can be studied by viewing under scanning electron microscopy.
2.6.12. Stability studies: The thermal stability of formulations is studied by placing the shampoo in glass tubes and then these are placed in a humidity chamber at 45°C and 75% relative humidity. For three months the colour and stability are observed.
2.7 Packaging of Shampoos
Packaging of shampoo is one of the important determinants of its market appeal, besides its quality. The shampoo package should contain necessary information such as name of the product, brand, composition, usage instruction and warnings. Also the container should be made such that to allow the product to come out but not to go in so that any contamination is avoided.
Another thing to be kept in mind while packaging is pilfer resistance. All containers must bear a seal which is broken when the product is opened for the first time. This ensures that the product is safe and tamper proof.
Ideal requirements for packaging:
1. The packaging must be able to protect the product from environmental conditions.
2. The packaging material must not be reactive with the product.
3. The packaging should not impart to the product odour.
4. The packaging material must be nontoxic.
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5. The packaging must meet the tamper-resistance requirements.
Sachets: Sachets are small pouches which are very flexible; require very less storage space and easy to carry along. Now a day's sachets are used for almost all shampoos. This is very convenient for users if they want to try new products. This help them to save their money and due to their flexible packaging they are easy to carry specially during journey.
Bottles: As per Indian Standards, shampoo shall be packed in a glass or plastic container with proper sealing. However the bottles must be light weight, convenient to use, tamper proof and reusable.
2.8 Indian Bureau of standards for shampoos
The liquid shampoo should be transparent/clear. They shall be free any sediment. In case when the shampoo is an emulsion, it shall be homogeneous. Moreover, there shall be no visible signs of phase separation. Shampoo available as paste shall be free from any agglomerated particles (Ref: Bureau of Indian Standards, 2004)
Requirements for shampoo:
S.No Characteristic Requirement
1 Non-volatile alcohol soluble matter (% by mass), Min 10
2 pH 4 - 9
3 Height of foam for 2 % solution, Min 150 mm
(Ref: Bureau of Indian Standards, 2004)
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3.0 Hair Creams
Hair creams are thick emulsions which are applied to the hair. They can be either oil-in-water or water-in-oil type. Water-in-oil type have more holding capacity than the former and provide better gloss to the hair. They may or may not be perfumed and are generally white, offwhite or uniformly coloured. The basic purpose of using hair creams is to condition the hair by moisturizing. For moisturizing the hair, direct application of water is of little use because water gets evaporated soon. Thus, there should be a method of retaining the absorbed water and prevent it from evaporating. For this purpose the emulsions of oil and water are useful. Ideally the emulsion should break down readily on application to the hair, water would be absorbed and oil or fat would form a protective film on the hair shaft, thereby minimizing the damage by pollutants. Thus, the hair creams are meant to mositurise the hair, provide good lusture without greasiness, condition the hair and protect hair from wind, rain, heat etc.
Advantages of Hair Creams
Protect the hair cuticle.
Clean without stripping natural oils.
Replace lost proteins and nutrients.
Condition without weighing down the hair.
Prevent moisture loss
Prevent intense drying from the environment.
Intensive treatment creams: These are not used on a regular basis and are used for intensive treatment. They contain higher level of active ingredients that are kept on the hair for a longer period of time. These are generally very thick and provide perception of higher conditioning along with the therapeutic effect.
4.0 Hair Conditioners
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Hair conditioner is a hair care product that changes the texture and appearance of hair. Hair conditioners are often viscous liquids that are applied to the hair and massaged into the hair. Hair conditioner is usually used after washing the hair with shampoo. Hair conditioners may contain moisturizers, oils and sunscreen, among other ingredients.
Mechanism of action of Hair conditioners
Hair conditioners basically replace the natural oils that shampoo strips away when hair are washed. They usually contain one or more fats, oils, or synthetic compounds that behave like fats and oils, surfactants, and a bunch of other stuff that makes it more marketable (perfumes, dyes, preservatives, etc.). The fats or oils (natural or synthetic) leave a smooth, waxy coating on the hair, making the hair smooth and shiny.
Hair is made up of an outer layer called the cuticle, a second layer called the cortex, and an inner layer called the medulla. Hair tangles when the lifted or frayed edges of the cuticle layer on one hair get caught on the cuticle layer on another hair. The way conditioning fights tangles is that it strengthens the cuticle or, where cuticle cells have broken away, forms a protective layer over the cortex. This coating essentially smooths out the rough edges along the cuticle layer and thus can keep the hair from tangling as easily. The coating also seals in moisture and helps reduce static electricity.
Ingredients
There are several types of hair conditioner ingredients, differing in composition and functionality:
Moisturizers: Its role is to hold moisture in the hair. Usually these contain high proportions of humectants.
Reconstructors: They usually contain hydrolyzed protein. Their role is supposedly to penetrate the hair and strengthen its structure through polymer crosslinking.
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Acidifiers: They are pH regulators and helps in maintaning conditioner's pH at about 3.5.
In contact with acidic environment, the hair's somewhat scaly surface tightens up, as the hydrogen bonds between the keratin molecules are strengthened.
Thermal protectors: They are usually heat-absorbing polymers, shielding the hair against excessive heat, caused by, e.g., blow-drying, curling irons or hot rollers.
Glossers: They are light-reflecting chemicals which binds to the hair surface. Usually polymers, mainly silicones, e.g., dimethicone or cyclomethicone are used.
Oils (EFAs - essential fatty acids): They help dry/porous hair become more soft and pliable. The scalp produces a natural oil called sebum. EFAs are the closest thing to natural sebum (sebum contains EFAs).
Surfactants: Approximately 97% of hair consists of a protein called keratin. The surface of keratin contains negatively charged amino acids. Hair conditioners therefore usually contain cationic surfactants, which don't wash out completely, because their hydrophilic ends strongly bind to keratin. The hydrophobic ends of the surfactant molecules then act at the new hair surface.
Types
Pack conditioners: Pack conditioners are heavy and thick, with a high content of surfactants which are able to bind to the hair structure and "glue" the hair surface scales together. These are usually applied to the hair for a longer time. The surfactants are based on long straight aliphatic fatty acid chains similar to saturated fatty acids. Their molecules have a tendency to crystallize easily, giving the conditioner higher viscosity, and they tend to form thicker layers on the hair surface.
Leave-in conditioners: Leave-in conditioners are thinner and have different surfactants which add only a little material to the hair. They are based on unsaturated fatty acid chains, which are bent, not straight. This shape makes them less prone to crystallizing,
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making a lighter, less viscous mixture and providing a significantly thinner layer on the hair. The difference between leave-in and pack conditioners is similar to the difference between fats and oils. Leave-in conditioner is designed to be used in a similar way to hair oil, preventing the tangling of hair and keeping it smooth. Its use is particularly prevalent by those with naturally curly or kinky hair.
Ordinary conditioners: Ordinary conditioners combine some aspects of both pack and leave-in ones. These are generally applied directly after use of a shampoo, and manufacturers usually produce a conditioner counterpart for this purpose.
Hold conditioners: Hold conditioners are based on cationic polyelectrolyte polymers and help in holding the hair in a desired shape. These have both function and composition similar to diluted hair gels.
5.0 Summary
Hair are simple thread like structures (about 50-100 µm in diameter) and are found over entire body and serves as a protective layer. The composition of a normal hair is 45.2 % carbon, 27.9%
oxygen, 6.6% hydrogen, 15.1% nitrogen and 5.2% sulphur. Among all proteins, keratin roughly constitutes 65–95% of the total volume, remaining matter of hair is filled with water and lipids. Structurally hair consists of hair shaft, hair bulb and hair follicle. Growth of hair takes place at different rates in different people. Average rate of hair growth is around one-half inch per month. Hair care products include shampoos and conditioners which aid in the maintenance and grooming process. A shampoo can be defined as a detergent solution which is modified by additives to make it easier to apply and to safeguard against deterioration of the hair condition after the shampoo has been rinsed away. Shampoos are primarily used to clean the hair and scalp. On the basis of appearance shampoos are broadly classified as clear shampoos, gel shampoos, paste shampoos and powder shampoos. On the basis of functions, they are divided into conditioning shampoos and anti-dandruff shampoos. A shampoo formulation contains various ingredients such as cleansing agents, thickening agents, conditioning agents, opacifying
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agents, pH balancing agents, preservatives and various medically active ingredients. Shampoos are evaluated for various parameters such as physical appearance, pH, percent of solids contents, viscosity, cleaning action, foaming ability, skin sensitization test and eye irritation test. Shampoo shall be packed in a glass or plastic container with proper sealing. However the bottles must be light weight, convenient to use, tamper proof and reusable.
