Natural Hair Dye Versus Chemical Hair Dye Biology Essay

This experiment was designed to look into and compare the extent of harm to the hair shaft construction caused by henna as the selected natural hair dye and chemical hair dye. The qualitative analysis of hair utilizing a hair hygrometer shows the fluctuation in hair strand length in a fixed moist status differ between the of course and chemically bleached hair. The average length of extension represents the grade of harm of the hair as the hair dyes interfere with the hair shaft construction, doing more H2O to be absorbed into the hair shaft. The statistical t-test with significance degree of 0.05 showed that the average extension length of the chemically bleached hair is significantly larger than that of the of course bleached hair. The consequences support the experimental hypothesis that chemically dyed hair is more damaged than of course dyed hair.

Research and Rationale

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Hair coloring is a chemical procedure affecting a series of complex reactions between chemicals in the hair-colouring merchandise with chemicals and biochemical in hair to alter the hair coloring material. The chemicals prepare the hair to accept the hair dye, alter the hair shaft biological science to maximise color alteration and put the dye to do the coloring material alteration permanent.

The hair shaft is composed of two major constituents – the cerebral mantle ( mostly keratins ) and the cuticle ( made up of thin graduated tables of dense ceratin and a lipid coating ) . To alter hair coloring material, the protective oils on the hair shaft have to be partly removed by a bleaching agent, normally H peroxide that oxidizes the melanin pigment in hair, doing it colourless. The most common chemical hair dyes used are para dyes, incorporating paraphenylenediamine ( PPD ) solutions which combine with H peroxide to make indissoluble molecules which are contained within the cerebral mantle and are unable to go through through the cuticle beds, go forthing coloring material to the hair. , Due to the bleaching agent and ammonia nowadays in dyes, alterations in the structural ceratins and protective oils make the hair shaft desiccant and more toffees, weakening the whole hair construction.

Natural replacements have been explored to minimise the hazard of side effects of chemical hair dyes. In fact, many natural agents like workss and minerals have been used for hair coloring for 1000s of old ages. These agents contain natural bleaching agents that change hair coloring materials by surfacing the hair shaft with coloring material. For illustration, henna ( Lawsonia inermis ) is a little tree turning to six metres high. Its coloring belongingss are due to the presence of lawsone, an organic compound that has an affinity for adhering with protein. This compound is extremely concentrated in the foliage leafstalks and gives a reddish-orange coloring material. Natural hair dyes like henna are non-toxic but some believe that they are non needfully safer or gentler than modern preparations as consistent consequences are difficult to be obtained and allergic reactions may originate in different persons.

Therefore, this experiment was aimed to compare the extent of harm to the hair shaft caused by natural and chemical hair dye. In this experiment, the extents of harm caused by several dyes are compared in footings of their response to wet in the air. Hair expands as air humidness additions and frailty versa. Due to the harm by hair dyes, the ability of the hair strand to absorb H2O is affected.

The consequences from this survey can be used to demo that chemical hair dyes alter the hair shaft construction more than natural hair dyes. This proves that natural hair dyes are able to supply a non-toxic pick for hair dyeing that produces good consequences. Hence, this besides eliminates the hazards of harmful chemicals present in the chemical hair dyes whereby some carcinogenic chemicals believed to be present has become a great concern.

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Experimental Hypothesis

There is a important difference between the harm to hair construction due to chemical hair dye and natural henna dye. Chemical hair dye causes more harm to the hair shaft construction compared to the henna dye.

Null Hypothesis

There is no important difference between the harm to hair construction by chemical and natural henna dye.


Manipulated: Types of hair dye

Reacting: Average length of hair extension

Fixed: Condition of hair strands before dye-ing, length of hair on hygrometer, humidness in bell jar, temperature of milieus

Apparatus and Materials



Hair dyes

Boar bristle coppice, fictile baseball mitts, two 250ml beakers, hair coloring coppice, glass rod

Hair strands

Henna dye

Pestle and howitzer, sift, 10ml measurement cylinder

Henna dye

50g henna foliages, acetum

Chemical Hair Dye

50ml lasting pick hair coloring material ( Ingredients: aquq, stearyl intoxicant, ammonium hydrated oxide, isostearic acid, oleth-10, propylene ethanediol, ammonium laurl ulphite, dehydrol 2409, merouat plus 3330, Na ulphite, sodium erythorbate, tetrasodium edentate dehydrate, aroma, p-phenylenediaminesulfate ) , 6 % pick peroxide


Wood piece ( 7.5cm X 20cm ) , fictile paper, 2 little nails, dime, tape, cock, scissors, bell jar, two 100ml beakers, meter regulation, vernier calliper

Hair strands ( unbleached, henna dyed and chemically dyed ) , distilled H2O

Table 1: List of setup and stuffs used in the experiment

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Determining observation method & A ; alteration

Trial experiments were conducted to obtain the best observation method to compare the extent of harm between natural and chemical hair dye.

Microscopic observations

Due to ammonia present in hair dye, the hair shaft crestless waves, coercing the cuticle scales to divide somewhat. The caustic belongings of ammonium hydroxide wears away the hair shaft. Under the microscope, hair treated with ammonium hydroxide will resemble Swiss cheese, harmonizing to the Organic Colour Systems web site. Hence, the figure of interruptions on the hair strand could be counted under the microscope to compare the harm caused by natural and chemical hair dyes. The hair strands were placed onto a microscopic slide. About two beads of distilled H2O were dropped onto the slide. The hair strands were viewed under microscopic power 40X. An optic and a phase micron were used to mensurate the length of strand. Two strands were observed for natural and chemical hair dye severally. ( Appendix Figure 2 )

Hair Hygrometer

Due to the loss of sebum on the outer bed, bleached hair loses ability to drive H2O. Alternatively, H2O is absorbed, doing the hair to be more delicate. Therefore, the grade of harm by hair dyes can be compared by mensurating the extension of hair strands under fixed moist conditions utilizing a meter regulation. Furthermore, a control group utilizing un-dyed hair strands was included to bespeak that the harm were significantly shown through the extension of hair length on the hygrometers.

Method 1

Calibration Value ( Aµm )


Phase micron: Number of millimeter

Eyepiece reticle: Number of intervals



40 eyepiece units



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Consequences for both methods are shown in the tabular arraies below.

Henna Dye

Chemical Dye

Number of eyepiece units



Length of strand ( millimeter ) = figure of eyepiece units X standardization value



Number of interruptions



Number of interruptions on strand for every 10mm



Table 2: Number of interruptions on hair strand with regard to hair dyes

Method 2

Mean Length of Hair Extension ( millimeter )


Henna Dye

Chemical Dye



3 strands


3 strands


Experiment 1







Table 3: Average extension in length of hair with regard to hair dyes

Based on the consequences above, the hair hygrometer method was selected as it showed important difference of harm on hair strand between henna dye and the chemical dye. There were some interruptions of the hair strand that were equivocal, hence whether to take into history a interruption or non depends on the perceiver. The dependability of the microscopic method is therefore less compared to the hair hygrometer method.

The meter regulation used to mensurate the length of hair extension in the hygrometer method has merely accuracy up to 0.1cm. Hence, to better truth of the consequences as the readings are little, a vernier caliper mensurating up to 0.02mm was used.

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Experimental Procedures

Appendix Figures 2, 3, 4

Reaping hair for dyeing

Un-dyed hair strands were collected from 10 female samples.

The hair strands were shampooed and rinsed with H2O to take any drosss.

The hair strands were divided into 2 groups – of course and chemically dyed group severally.

Fixing henna dye

Using stamp and howitzer, dried henna foliages were grind equally into pulverization and sifted.

The sifted pulverization was transferred to a 250ml beaker and 10ml of acetum was added to rush the dye release procedure.

The mixture was stirred with a glass rod until the henna pulverization is wholly dissolved and a thick paste was formed. Vinegar was further added until the coveted creamy consistence was reached. The paste was left aside for 24 hours to let the henna dye to be wholly released.

Dying hair strands utilizing henna

Hair strands secured at one terminal with tape were placed assorted with the henna paste utilizing glass rod.

A coppice was used to brush the hair strands to guarantee even distribution of dye on the strands.

The beaker was left aside for 4 hours so rinsed with H2O thoroughly and left to dry.

Dying hair strands utilizing chemical hair dye

The 50ml lasting pick hair coloring material and 6 % pick peroxide were assorted exhaustively utilizing a glass rod in the 250ml beaker.

Repeat steps 7 to 9 utilizing the chemical dye but leave merely for 45 proceedingss.

Fixing the set up of the hygrometer

The fictile paper was cut into a triangular form to do the arrow of the hygrometer. The dime was taped onto the plastic near the point. One nail was poked through the plastic arrow near the base of the trigon. The other nail was nailed on the upper portion of the wood piece.

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The arrow was nailed 12.5cm off from the first nail onto the wood piece. The arrow should travel freely and slackly about the nail.

Three natural dyed hair strands were taken. One terminal was taped to the nail on the upper portion ; the other onto the arrow. The strand ends that were excessively long were trimmed. It was made certain that the hair strands hung absolutely perpendicular from the nail to the arrow. The hair strands were pulled directly and tight so that the arrow points parallel to the land ( perpendicular to the hair ) .

Stairss 12 to 14 were repeated so that two hygrometers were made utilizing henna-dyed and chemically bleached strands severally.

Recording Observations utilizing Hygrometer

The initial point on the wood piece at which the arrow points was marked. The two hygrometers were placed inside a bell jar each with two 100ml beakers of distilled H2O for 3 hours severally.

After 3 hours, the new point at which the arrow points was marked and the length of the arrow from its original point was measured.

Stairss 16 to 17 were repeated utilizing new sets of hair strands to obtain 10 sets of consequences.

Hazard Appraisal

As chemicals were involved, protective baseball mitts were worn during the hair dyeing procedure. Henna dye may do allergic reactions on tegument of peculiar persons while the bleaching agent, peroxide pick nowadays in the chemical hair dye is caustic. Hence, protective wear were used to minimise contact with tegument and eyes.

All the glasswork used including bell jar, mensurating cylinders, glass rods and beakers must be handled with excess attention as they are easy breakable and may do hurt. Besides that, the hair strands might interrupt easy so excess attention is taken when the hair strands were attached to the hygrometer.

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Experiment Set

Length of extension of hair ( millimeter )

Henna Dye

Chemical Dye

3 strands


3 strands























































Table 4: Lengths of extension of hair with regard to hair dyes.

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Figure 5: Bar Chart of average length of hair extension with regard to hair dyes

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Statistical Analysis

The t-test was chosen as the statistical trial for the experiment to demo the significance of difference between the agencies of two independent samples ( natural and chemical hair dyes. )


Henna Dye

Chemical Dye







xI„ = a?‘x/n









– xI„2



T =

a”‚xI„1 – xI„2a”‚



a”‚ 4.803 – 9.339 a”‚

a?s ( s12/n1 ) + ( s22/n2 )

a?s ( 0.175341/10 ) + ( 1.137019/10 )


xI„1= mean of sample 1 ( henna dye )

xI„2= mean of sample 2 ( chemical dye )

n1= figure of topics in sample 1

n2= figure of topics in sample 2

s12= discrepancy of sample 1

s22= discrepancy of sample 2



grades of freedom, df= n1+ n2 – 2 = 10 + 10 – 2 = 18

significance degree, I± & lt ; 0.05

tabulated t-value= 2.101

calculated t-value= 12.52

Therefore, ttable & lt ; tcalculated

Table 5: Calculations for t-test

The average length of extension of hair dyed with chemical dye is significantly longer than that bleached with henna. The deliberate t-value ( 12.52 ) shows that it is important whereby it exceeds the tabulated t-value ( 2.101 ) . Therefore, the experimental hypothesis is accepted and the void hypothesis rejected.

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Datas Analysis

The average extension of the chemically bleached hair is 4.54mm longer than that of the henna-dyed hair. This gives a per centum difference of 48.6 % between both dyes. Mistake bars are displayed on the saloon chart to relay 95 % assurance degree in the information. The scopes in both dyes do non overlap ; intending that the two mean values are significantly different. Hence, it suggests that the experimental information is sufficient to turn out the experimental hypothesis.

The control uses un-dyed hair strand. It showed alteration in length, bespeaking that hair is hygroscopic. This is achieved by capillary action whereby H2O vapor diffuses through the minute infinites of the hair despite the close fitting graduated tables of cuticle and sebum. This is the basic working rule of the hair hygrometer. A comparative little alteration in the control group proves that hair dyes affected the hair construction and permeableness to H2O.

The hair dye alters the protective oils on the cuticle layer,4 so H2O vapor diffuses easy into the hair, doing it to swell. The extension in hair length was shown by the motion of the hygrometer arrow. As the hair strand extended, the arrow moved downwards, pulled by the weight of the dime. The less damaged the hair construction is, less H2O is able to spread into it in a fixed clip. Therefore, the extension in hair length is a step of the hair dye ‘s detrimental belongings.

The per centum addition in length of the chemically bleached hair is 7.5 % while that of henna dyed hair is 3.8 % . This corresponds to the information from beginning [ 10 ] whereby it states that a hair in good status absorbs more than 30 % of its ain weight of H2O ; for damaged hair, this per centum reaches 45 % , therefore length increases up to 2 % .

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Loose hair was taken from several female topics so the conditions of the hair strands before dyeing demand to be changeless: hair strands collected were wholly natural and un-dyed ; short hairs less than 12.5cm were discarded ; attention taken to guarantee that the strands did non interrupt when being extracted from the hair coppice. Furthermore, hair strands were cleaned before dyeing so that any oil or drosss on the strands do non impact the consequences. Three strands were used on the hygrometer as a individual strand is easy broken.

However, the length of dye clip for both dyes could non be fixed the same. This is because for optimal dyeing, henna dye requires a longer clip as it does non incorporate chemicals which are able to respond fast to perforate the cuticle.

There may be mistakes due to the restrictions of the hair hygrometer. Hair expands or shrinks non merely in response to humidness but besides temperature. The enlargement or shriveling matching to a temperature alteration of 1oC is about 1/15 of that matching to a temperature alteration of 1 % in usual air temperatures. Hence, environing temperature has to be kept changeless at all times so that this factor does non impact the cogency of the consequences. The hair hygrometer is a mechanical instrument which contribute to mistakes like ‘setting ‘ of the hair strand if remained at a changeless humidness for drawn-out period of clip and decelerate response times. Therefore, a suited period of clip demands to be determined to minimise both these mistakes.

The experiment could be modified by mensurating the diameter of the hair strand under microscope to obtain consequences. The hygrophobic belongings of hair can non merely be measured in footings of length but besides diameter. Harmonizing to beginning [ 10 ] , damaged hair can increase by 15 % to 20 % in diameter. The consequences obtained would be more accurate as hair strands are measured singly. Furthermore, the tensile strength of hair can be investigated as hair dyes affect the strength of the hair shaft. An extensiometer can be used to increasingly stretch the hair at the rate of 1cm/minute, leting precise measuring and comparing of the interrupting point of bleached hair.

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Chemical hair dyes are significantly more detrimental to the hair shaft compared to natural hair dyes. This was determined by the average extension of the bleached hair on the hygrometer. There is a statistically important difference between the average extension length of hair and the extent of harm of natural and chemical hair dyes. Experimental hypothesis is accepted and void hypothesis is rejected.

Beginning Evaluation

Beginning 12 is an on-line diary obtained from the on-line database from my campus library. ScienceDirect is a taking full-text scientific database offering more than 2500 peer-reviewed diaries and more than 11000 books. There are presently more than 9.5 million articles/chapters. Hence, this is a extremely dependable beginning.

I have besides obtained information about hair dyeing from a scope of beginnings. Beginning 1, Hair Foundation is an organisation that provides believable and the most recent scientific information on hair wellness to the populace. It is considered a sure beginning as the other cross-referred web sites ( beginnings 3 and 5 ) have similar and relevant facts as beginning 1.

The on-line diary ( beginning 2 ) is another reliable beginning as the author, Desmond J. Tobin, a medical life sciences PhD holder from the University of London, UK ( St. Thomas ‘s Hospital Medical School ) , is experienced in this subject and cited a batch of trustable mentions. This article is published by the Royal Society of Chemistry, one of the largest publishing houses of chemical scientific discipline information in the universe. The quality content of the books, databases, diaries and magazines are therefore really dependable.

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