Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 1
THE CHEMISTRY OF HAIR RELAXING
Cosmetology II
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 2
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Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 3
CHEMICAL HAIR RELAXING
A process or service that rearranges the structure
of curly hair into a straighter or smoother
form
Copyright © Texas Education Agency, 2014. All rights reserved.
All relaxers and all permanents change the shape of the hair by breaking disulfide bonds.
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 4
CHEMICAL HAIR STRUCTURE
• Hair is made up of:
• Protein – 90%
• Carbon – 51%
• Oxygen – 21%
• Hydrogen – 6%
• Nitrogen – 17%
• Sulfur – 5%
Copyright © Texas Education Agency, 2014. All rights reserved.
The elements in hair are also known as: COHNS Elements C – Carbon O – Oxygen H – Hydrogen N – Nitrogen S – Sulfur These elements are also found in skin and nails.
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 5
HAIR ANALYSIS
• Hair proteins are made of amino acids
• The cortex is made up of polypeptide chains
• These chains are cross-linked by side bonds
• Types of side bonds include:• Hydrogen bonds
• Salt bonds
• Disulfide bonds
Image from Wikimedia Commons, the free media repository
Copyright © Texas Education Agency, 2014. All rights reserved.
Strand of human hair at 200x magnification
Polypeptide chains cross-linked with side bonds together are responsible for the extreme strength and elasticity of human hair. Hydrogen and salt bonds can be broken by heat and moisture. Disulfide bonds are strong and can be broken by chemical hair relaxers that alter the shape of hair.
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 6
DISULFIDE BONDS
• Strong, chemical side bond
• Cannot be broken by water
• Can be broken by chemical hair relaxers
• Alters the shape of the hair
Copyright © Texas Education Agency, 2014. All rights reserved.
Hair relaxers straighten the hair by breaking disulfide bonds and the neutralizer hardens the hair in its straight form.
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 7
RELAXERSThio Relaxers
Hydroxide Relaxers
Sodium Hydroxide
Two most common hair relaxers are thio and sodium hydroxide relaxers.
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 8
THIO RELAXERS
• pH factor of 10 and higher
• Thicker which helps hold hair in a straight position
• Hair softens and swells during the relaxer process and disulfide bonds are broken
• A neutralizer is used to rebuild disulfide bonds
Copyright © Texas Education Agency, 2014. All rights reserved.
The neutralizer provides an oxidation reaction that rebuilds the hair bonds in a straightened form. It breaks bonds by adding hydrogen atoms to the two sulfur bonds within the disulfide bond. Hydrogen peroxide is usually used.
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 9
HYDROXIDE RELAXERS
• Active ingredient is hydroxide ion
• Highly alkaline product ranging usually from a pH of 12-14
• Types include:
• Sodium
• Potassium
• Lithium
• Guanidine hydroxide
Copyright © Texas Education Agency, 2014. All rights reserved.
Hydroxide relaxers are not compatible with thio relaxers because they use a different chemistry.
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 10
SODIUM HYDROXIDE(NaOH)
• Commonly called lye relaxers
• Most common type of hair relaxer
• Highly caustic
• pH is often over 13.5 which is highly corrosive
Copyright © Texas Education Agency, 2014. All rights reserved.
Sodium Hydroxide is the same chemical used in drain cleaners and chemical hair depilatories
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 11
THE BASICS OF CHEMISTRY
(click on link)
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Image from video
Click on hyperlink to view video: Basics of Chemistry Clip from the Milady Standard Cosmetology 2012 DVD Series http://youtu.be/N0PVlegJv8Y
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 12
WARNING
Caution is advised as relaxers can literally dissolve or melt
the hair
Copyright © Texas Education Agency, 2014. All rights reserved.
Be sure to wear gloves and protective clothing when mixing chemicals. Always follow manufacturer’s processing directions.
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 13
QUESTIONS?
13
Copyright © Texas Education Agency, 2014. All rights reserved.
Presentation Notes The Chemistry of Hair Relaxing
The Chemistry of Hair Relaxing Copyright © Texas Education Agency, 2014. All rights reserved.
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Slide 14
REFERENCES AND RESOURCES
Images:
• Microsoft Office Clip Art: Used with permission from Microsoft.
• Wikimedia Commons, the free media repository
Textbook(s):
• Halal, J. (2009). Hair structure and chemistry simplified: Exam review/John Halal. Clifton
Park, NY: Milady/Cengage Learning.
• Milady standard cosmetology: Situational problems. (2012). Clifton Park, NY: Cengage Learning.
YouTube™:
• Basics of Chemistry
Clip from the Milady Standard Cosmetology 2012 DVD Series
http://youtu.be/N0PVlegJv8Y
Copyright © Texas Education Agency, 2014. All rights reserved.