Hair Structure, Melanin, Canities, and Gray Hair Color Concepts (Transcript-Based Notes)

Hair Structure and Color Concepts

  • Hair is composed of three main layers: cuticle, cortex, and medulla.

    • ext{Layers of hair} = 3
    • The cuticle is the outermost layer consisting of flattened scale-like cells. When these cuticle scales lie flat and intact, hair looks healthy; if the cuticle is open or damaged, hair appears fried.
    • The cortex lies beneath the cuticle and is responsible for the hair’s color, body, and structural integrity.
    • The medulla is the innermost layer. Some people do not have a medulla in their hair.
    • The transcript notes that the medulla has "no true effect" on hair, though studies continue to explore its function.

  • Cuticle: outer protective layer

    • Made of flat scales that lie flat when the cuticle is healthy.
    • Damaged or lifted cuticle indicates fried hair.

  • Cortex: middle layer

    • Responsible for bonding together color, appearance, and body.
    • Contains keratin; accounts for about 90\% of hair’s weight.

  • Medulla: inner layer

    • Not present in all hairs (some people lack it).
    • Its function is not clearly linked to hair properties; current understanding suggests minimal direct impact on hair characteristics.

  • Melanin and hair color basics

    • There are two main types of melanin in hair:
    • Eumelanin (brown/black range)
    • Pheomelanin (yellow to red range)
    • The combination and ratio of these melanins determine the natural hair color spectrum.
    • Transcript notes mention two types as: "humelanin" and "bowel melanin" due to mishearing; the academically correct terms are eumelanin and pheomelanin. The class discussion confirms that eumelanin yields brown/black tones, while pheomelanin yields yellow/red tones.
    • When both melanin types are present, the resulting color depends on their relative amounts.

  • Mixed melanin and canities

    • When hair contains both melanin types in varying amounts, it produces a range of shades from natural color to gray.
    • The term for gray hair is canities; two types are discussed:
    • Acquired canities
    • Congenital canities
    • Acquired canities: melanocytes gradually become inactive over time.
    • Congenital canities: can be present at birth or occur early; can be observed in some family members.
    • Transcript notes expressed as: acquired means hair has become gray over time; congenital means present from birth or developed with age.

  • Canities terminology and inheritance

    • Canities can be categorized as acquired or congenital.
    • In practice, acquired canities tends to develop with age due to gradual melanocyte inactivity.
    • Congenital canities can be present at birth and can appear in families.

  • Graying patterns and percentages (gray hair distribution)

    • For someone with 30%–60% gray hair, the appearance is typically salt-and-pepper.
    • For 0%–30% gray, gray strands are scattered throughout the hair rather than forming a uniform pattern.
    • For 60%–100% gray, hair is predominantly gray with notes of natural hair color still visible in some strands.

  • Reasons gray hair may yellow and remediation

    • Yellowing can occur due to:
    • Flat iron use (heat processing)
    • Sun exposure
    • Smoking
    • Certain medications
    • Other factors may contribute to yellowing (not exhaustively listed in transcript).
    • Remediation/utilities discussed:
    • Purple shampoo or purple toning products can help offset yellowing.
    • Pre-softening treatments may improve pigment uptake when coloring gray hair.
    • A color-cap or pre-treatments may be used to soften and prepare the hair for dye uptake.

  • Color formulations and processing notes from the transcript

    • Demi-permanent color uses a low-volume developer; the class recalled using volume 10 for demi-permanent formulations.
    • For full coverage of gray hair, a higher-volume developer is needed, and the class stated volume 20.
    • Pre-softening or pre-treatment steps may be employed to improve color penetration on resistant gray hair.
    • Purple shampoo is cited as a method to counteract yellowing, especially for gray or white hair.
    • Cap-based coloring or conditioning caps may be used to help deposit color or act as a conditioning step during color service.

  • References to course material and page

    • The instructor directed focus toward page 293 of the referenced material.
    • The discussion includes practical salon applications for color coverage of gray hair and handling yellowing in gray hair.

  • Practical implications and connections

    • Understanding hair structure helps explain why cuticle health affects color uptake and shine.
    • Recognizing the cortex’s role in color and body clarifies why damage to cortex alters appearance and how keratin content influences strength.
    • Differentiating eumelanin and pheomelanin informs how natural hair color is formed and how gray hair emerges as melanin production changes.
    • Distinguishing acquired vs congenital canities informs expectations for clients and treatment planning (timelines for graying, restoration options).
    • Gray hair distribution percentages guide stylist decisions about color formulas, blending, and level compatibility to achieve natural-looking results.
    • Addressing yellowing requires selecting appropriate toners or shampoos; understanding factors like sun exposure and heat styling helps educate clients on maintenance.

  • Summary of key numerical references

    • Hair layers: 3
    • Cuticle scales: 7\text{-}12 per hair strand
    • Cortex weight: 0.90 (i.e., 90% of hair weight)
    • Gray hair distribution patterns:
    • 0\%\le\%\le 30\%: scattered
    • 30\%\le\%\le 60\%: salt-and-pepper
    • 60\%\le\%\le 100\%: predominantly gray
    • Demi-permanent developer volume: 10
    • Gray coverage developer volume: 20
    • Notation of page reference: page 293

  • Notes on terminology accuracy

    • Correct terms: eumelanin and pheomelanin; hair color results from their ratios
    • Correct term for gray hair: canities; two types: acquired and congenital
    • When presenting to clients, cite these terms accurately to ensure clarity and professional communication