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The Effect of Shampoos on the Tensile Strength of Hair

Researched by McKenzie



The purpose of this experiment was to determine how various shampoos affect the tensile strength of human hair. 

I became interested in this idea when my mom told me that my hair could look better if the strands of hair were stronger. 

The information gained from this experiment will help people know which shampoo will make their hair stronger so it won’t break off easily.  Consumers will also know which brand to buy so that their hair is stronger and healthier.  I think that this will be very beneficial for the hair stylists and consumers who are concerned about their hair.
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My hypothesis is that Pantene Pro-V will give the hair the greatest tensile strength.  I base my hypothesis on the opinion of numerous hairstylists that I have contacted. 

My hypothesis is based on Andre Walker’s professional opinion.  Andre said that the more moisture that the hair contains the healthier the hair is.  He also said that the shampoo should be full of protein and natural herbs. I think that Pantene Pro-V will work the best.
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Experiment Design

The constants in this study were:
1.   The amount of the shampoo that was put on hair
2.   The amount of the water used to rinse the hair
3.   The gauge and method used to measure the pressure
4.   The type of hair
5.   The amount of the hair that I used

The manipulated variable was the type of shampoo that the hair was soaked in. 

The responding variable was the stretch force that the hair withstood before breaking.

To measure the responding variable I used a spring scale as a pressure gauge. 
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Quantity Item Description
1 Spring Scale Gauge
10ml Pantene Pro-V
10ml Thermisilk
10ml Pert Plus
1 250ml liter beaker
75 Strands of regular hair
4 Sheets of paper
1 Pencil
1 White cotton towel

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1 Gather 10 strands of hair for each of the 3 trials.
2 Gather 10ml of each of the following shampoos: Pert Plus, Thermisilk, and Pantene Pro-V. 
3 Mix one of the shampoos above with 250ml of water at 40*c.
4 Take 5 strands of hair that you’ve gathered and drop them into the shampoo/water mixture.
5 Swish the hair for 10 seconds
6 Rinse the 5 hairs in 250ml of clean water for 20 seconds
7 Take the strands of hair out of the water
8 Use a white cotton towel to dry the hair.
9 Dry the hair until it is almost dry
10 Use a pressure gauge to measure the pressure until the breakage point in the hair (until it snaps).
11 Take one strand of hair at a time and pull it until it breaks
12 Record the amounts of the pressure 
13 Average them out and write down the average amount of pressure for the shampoos
14 Repeat steps 1-13 to record what the other shampoos do to your hair.
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The original purpose of this experiment was to determine which shampoo would cause hair to hold against the most pressure.

The results of the experiment were that Pert Plus worked the best on seven of the trials; Thermisilk worked best on one and Pantene Pro-V on two.  These tests suggest that Pert Plus worked the best out of the three shampoos.
See the graph below.

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My hypothesis is that Pantene Pro-V will give the hair the greatest tensile strength.  I base my hypothesis on the opinion of numerous hairstylists that I have contacted.

The results indicate that this hypothesis should be rejected because the shampoo Pert Plus was the best of all the three shampoos in increasing the tensile strength. 

Because of the results of this experiment, I wonder if I would have used other shampoos that the results would have still favored Pert Plus.

If I were to conduct this project again I would have tried to find more research because I started with to little understanding of shampoo and hair.  I would have used a lot more types of shampoo because I didn’t use all of the leading brands.  I would also have taken pictures so that the viewer could have been able to view the processing of the experiment.  I also would have conducted it with a more accurate method when I was measuring. The gram pressure scale was hard to use for really accurate and reliable measurements.

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Hair is made up of dead cells that combine into thousands of strands.  Each strand of hair contains thousands of dead cells.  Consumers spend millions of dollars each year on shampoo hoping to improve the looks and health of their hair. 

Hair is a part of your body that is used as a protection.  It is made out of dead cells.  Hair is used as a protection for the eyes, ears, and nose so that there is no bad matter that can reach the inside organs.  Hair has three main parts.  The Medulla, which is the center of the strand. Second is the Cortex.  The Cortex is the thickest layer in the strand of hair.  The outer layer is the Cuticle.

The shaft is the part of the hair or skin that comes above the scalp and is deprived of nourishment.  Next are the Sebaceous glands, which secretes oil into the Follicle.  This allows the oils to flow over the hair lubricating it, thus making the hair softer.  The Arrector Pili comes next. It is attached to most Follicles that are in the scalp.  Next is the Keratinization Zone.  When the hair reaches the Keratinization Zone the hair cells die.  Follicles are next.  They are attached to most of the Arrector Pili.  The Root follows the Arrector Pili.  The Root is so large that it contains the Hair Bulb, the Papilla, and the Blood Vessel.  The Hair Bulb is where the root gets lighter and expands into the Hair Bulb.  The Papilla is the part of the root that is in the Hair Bulb and is at the base of the Follicle.  The Blood Vessel is connected to the bottom of the Root.

 Shampoo; in order to be effective, needs to have the four main ingredients.  The first ingredient is glycerin.  The second ingredient is Shea butter that comes from a Shea tree.  The third ingredient is sulfur/carotene and last is protein.  Protein is a Greek word that was first discovered in 1838.

The main ingredients in soap are alkalis (a chemical), fats, and fragrance.  Other ingredients are also included.  Soap was first made in 600 AD. Pioneers also made it when they were traveling along the Oregon Trail and also by earlier people.  Usually if a person is hygienic the average amount of soap that they use in a year is 25 pounds.
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Hair is made out of dead cells.  It is a protection function for the eyes, the ears, and the nose.  The hair protects bad matter form entering the inside organs.  Hair has several different parts that start at the root and go to the shaft.  The hair also has the parts of the Cortex, the Medulla, and the Cuticle.  Consumers today would like to buy the best shampoo to make their hair look better.  So there were tests taken that would tell which shampoo is the strongest out of the three shampoos Pert Plus, Pantene Pro-V, and Thermisilk.
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Walker, Andre, "Andre Talks Hair," Simon and Schuster, Andre Walker 1997 all shampoo pages

Woodley, David, "Hair," World Book Encyclopedia Vol. 9, pg. 9-10 1991


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