Glass Evidence Review

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Glass Evidence Review
2012-05-07 20:29:37
Glass evidence forensic science criminalistics

Made for "Introduction to Forensic Science & Criminalistics" by Gaensslen, Harris and Lee
Show Answers:

  1. Define glass.
    Hard (transparent~translucent), brittle material; made from molten inorganic material; non-crystalline
  2. What is the forensic value of glass?
    • - Ubiquitous
    • - Stable
    • - Easily broken and transferred
  3. Name and provide examples of compositional classes of glass.
    • Soda lime glass
    • - light bulbs
    • - bottles/containers
    • - headlamps
    • Borosilicate glass
    • - pyrex
    • Lead-alkali glass
    • - crystal
  4. What is soda lime glass composed of?
    Sand, soda and lime
  5. Name three different glass products of automobiles. Explain how they differ.
    • Tempered
    • - heated and rapidly cooled
    • - side and back windows
    • Laminated
    • - plastic sandwich
    • - windshield
    • Coated
    • - aluminum/chromium
    • - side mirrors
  6. Explain how the physical shape of an impact crater can be used to determine which direction a projectile was traveling.
    Narrow opening is the entry side; keyhole effect
  7. Recognize and distinguish radial and concentric (tangential) fracture lines in a glass fracture.
    • Radial
    • - radiate outward from center of point of force
    • Concentric (tangential)
    • - encircle/form a polyhedron around point of force
  8. State the 4R rule for glass fracture patterns.
    RIB marks on RADIAL cracks form RIGHT angles on the REVERSE side of the glass to that struck by a projectile.
  9. Name 6 features and/or properties of glass that are typically determined in the forensic examination of this evidence.
    • Color
    • Surface features
    • Flatness
    • Thickness
    • Density
    • Physical match
    • Fluorescence
    • Refracive index
  10. Describe two experimental approaches that can be used to determine the RI for a piece of glass.
    • Using GRIM
    • Vacuum/air and liquid/solid