fibers and paint Flashcards

1
Q

are fibers class evidence? can they be individualized?

A

-fibers are class evidence and no amount of testing allows for individualization of a fiber

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2
Q

what are the major sources of fiber? can you name multiple examples of each?

A
  1. Natural
    -plant origin (cotton, jute, hemp)
    -animal origin (wool, silk)
    -mineral origin (asbestos)
  2. Synthetic
    -nylon
    -polyester
    -acrylic
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3
Q

what is an example of a semi-synthetic fiber?

A

semi-synthetic fiber: a fiber that is made from a naturally occurring substance (rayon made from wood pulp residue)

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4
Q

what types of examinations are performed in the analysis of fibers?

A
  1. comparison microscopy
  2. polarized light microscopy
  3. micro-spectrophotometry
  4. fourier transform infrared spectroscopy
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5
Q

what is used to determine the color of fibers?

A

-color of fibers determined using micro-spectrophotometry (measure amounts of wavelength of visible light object absorbs)

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6
Q

what are the different types of paints? which one is the most common in forensic casework?

A
  1. automotive paints: *most encountered in forensic work
  2. structural paints: houses or structures
  3. artistic paints: long lasting and made from naturally occurring oils and pigments
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7
Q

what types of examinations/tests are performed in the analysis of paints?

A
  1. physical properties= most important characteristic
    -each layer can have different color and/or composition
    -determined using microscopic analysis
  2. chemical properties
    -solubility: determine possible solvent used as binder
    -pyrolysis gas chromatography
    -infrared micro-spectrophotometry (FTIR)
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