The Wonderful World of Hairs and Fibers

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The Wonderful World of Hairs and Fibers
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Different Scopes used to analyze hair and fiber

• Compound light
• Comparison
• Dissecting
• Polarized
• Scanning Electron Microscope (SEM)

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Stages of Hair Life

• Anagen
• Growing stage
• Up to 6 years possible
• Root shaped like flame
• Hair grows 1cm/month (1 every 10 weeks)

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Stages of Hair Life

• Catagen
• 3 weeks long
• Dormant, resting stage
• Root? gets longer and thinner

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Stages of Hair Life

• Telogen
• 6 months
• Root ?
• Club shaped
• Pushes out and is shed
• Lose approximately 70 hairs/day

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Human Hair Parts

• 1. Root
• 2. Follicle
• 3. Shaft
• 4. Tip

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2
3
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Human Hair Parts

• 1. Distal (tip)
• 2. Proximal (root end)
• 3. Medulla
• 4. Cuticle (contains scale pattern)
• 5. Cortex

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4
3
5
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Scale patterns

• Imbricated
• Mosaic
• Petal
• Pectinate
• Chevron

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Medulla Types

• Continuous
• Fragmented
• Intermittent/interrupted

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Medullary Index of Hair

• To find the MI
• Diameter of medulla/hair shaft diameter
• Humans
• Other animals 1/2
• Classify Medulla as
• Continuous, Interrupted, Fragmented, or Absent

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Example Medulla Patterns that can be seen

• Lattice
• Vacuolated
• Uniserial
• Multiserial

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Deer, Dog Muskrat hair
Deer
Muskrat
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Which is Caucasian, Negroid, Mongoloid Head Hair?
Caucasian, Europeans, Mexicans, Middle
Easterners oval to round
Negroid, Africans oval to flat
Mongoloid, Orientals, American Indians round
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Pulled Hair v. Shed Hair
Anagen Stage
Pulled Hair
Telogen stage
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Razor, Cut hair Split hair
Split
Razor
Cut
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Human eyebrow
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Burned hair
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Buckling of hair seen in pubic hair
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Hair match

• This is the view that a comparison scope can give
  when comparing two matching hairs

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The small things in life
Eyelash mites
Bedbug feeding on flesh
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Fibers
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Types of fibers

• Natural fibers
• Animal fibers are most common at crime scene
• Man-made

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Natural fibers

• Animal
• Wool from sheep most common
• Goats, camel, alpaca, rabbit, mink, llamas,
  beaver
• Plant
• Cotton most common
• Flax (linen), ramie, sisal, jute, hemp
• Excrement
• Silk from silkworm (cellulose from mulberry
  leaves)
• Mineral
• Asbestos

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Cotton fibers cross-section
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Wool fibers v. Cotton fibers
Cotton
Wool
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Flax Fibers
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Hemp fibers
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Silk fibers

• Raw thrown
• Wild silk

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Asbestos fibers
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Man-Made fibers

• Regenerated fibers
• Machine made from natural materials like cotton
  or wood
• 1910 rayon, then acetate, then triacetate
• Synthetic fibers
• Most fibers are made synthetically from chemicals
• 1939 nylon, then polyester and acrylic
• Shape or cross-section can determine value of the
  fiber manufacturer specific

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Nylon fiber cross sections
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Acetate Fibers
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Nylon fibers
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Orlon Fibers
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Polypropylene fibers