fibers and paint

Question 1

are fibers class evidence? can they be individualized?

Answer 1

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

Question 2

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

Answer 2

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

Question 3

what is an example of a semi-synthetic fiber?

Answer 3

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

Question 4

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

Answer 4

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

Question 5

what is used to determine the color of fibers?

Answer 5

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

Question 6

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

Answer 6

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

Question 7

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

Answer 7

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)