Lecture Notes on Hair Composition and Chemistry

Overview

• Fiber Composition: Discussion on fiber, patterns, and textures. Focus on similarities and differences.
• Melanin: Understanding natural levels and the balance of melanin, with an emphasis on warmth.
• Bonds: Explanation of hair protein molecules and breaking down proteins to understand their impact on hair. Introduction to side bonds in proteins.

Side Bonds in Hair

• Types of Side Bonds:

  • Hydrogen Bonds: Physical bond. Pulled apart by water and heat; reformed when dried or cooled.
  • Salt Bonds: Physical bond. Ionic positive/negative charges. Swell with negative charge.
  • Disulfide Bonds: Chemical bond. Strong, requires intentional breaking via chemical reactions.

• Breaking and Reforming Bonds:

  • Hydrogen bonds break and reform with water and heat.
  • Salt bonds break with a change in ionic charge.
  • Disulfide bonds break through chemical processes like oxidation, reduction, and ionization.

Chemical Processes Affecting Disulfide Bonds

• Oxidation: Using lighteners and permanent hair color. Involves hydrogen peroxide.
• Reduction: Involves hydrogen; applicable to perms and thiol relaxers.
• Ionization: Hydroxide relaxers break off sulfur leaving lanthionine bond.
• Longevity and Damage Prevention: Using lower volumes of developer, bonders, and careful application to minimize damage.

pH and Hair Chemistry

• Understanding pH:

  • Measures balance of positive hydrogen ions and negative hydroxide ions.
  • Scale: 0 (high positive, acidic) to 14 (high negative, alkaline), 7 is neutral.
  • Hair's natural pH: ~4.5.

• Impact of Products on Hair pH:

  • Water (pH 7) adds negative charge, causing swelling.
  • Acidic Demi Colors (pH 6-7) swell hair slightly.
  • Alkaline Demi Colors (pH 8.5) swell hair more than acidic.
  • Permanent Colors (pH 9.5-10) and Lighteners (pH 10-10.5) result in significant swelling and deeper dye penetration.

• Neutralizing and Conditioning:

  • Use low pH products to add positive charge and bring hair back to natural pH.
  • Multiple stages of positive charge application (shampooing, conditioning) are needed for effective de-swelling.

Practical Application and Considerations

• Chemical Treatments: Adjusting pH considerations for hair treatments and understanding cumulative effects.
• Detected Swelling: Balancing the de-swelling process by using appropriate after-treatment conditioners and multiple shampoos.

Activity: Measuring pH

• Testing Setup: Developer, color, and mixed solution in separate bowls, tested with litmus paper.
• Expected Results: Developer (low pH), Color (high pH), Mixed (intermediate, typically high).
• Importance of Accurate pH Understanding: Ensuring proper neutralizing and conditioning for hair integrity.

Key Takeaways

• pH plays a critical role in hair treatment outcomes.
• Chemical processes must be carefully managed to maintain hair health and manage damage.
• Practical hands-on testing of pH can help in understanding and predicting hair reactions.

Positive approach and mindset for applying this knowledge.