fibers and paint Flashcards
are fibers class evidence? can they be individualized?
-fibers are class evidence and no amount of testing allows for individualization of a fiber
what are the major sources of fiber? can you name multiple examples of each?
- Natural
-plant origin (cotton, jute, hemp)
-animal origin (wool, silk)
-mineral origin (asbestos) - Synthetic
-nylon
-polyester
-acrylic
what is an example of a semi-synthetic fiber?
semi-synthetic fiber: a fiber that is made from a naturally occurring substance (rayon made from wood pulp residue)
what types of examinations are performed in the analysis of fibers?
- comparison microscopy
- polarized light microscopy
- micro-spectrophotometry
- fourier transform infrared spectroscopy
what is used to determine the color of fibers?
-color of fibers determined using micro-spectrophotometry (measure amounts of wavelength of visible light object absorbs)
what are the different types of paints? which one is the most common in forensic casework?
- automotive paints: *most encountered in forensic work
- structural paints: houses or structures
- artistic paints: long lasting and made from naturally occurring oils and pigments
what types of examinations/tests are performed in the analysis of paints?
- physical properties= most important characteristic
-each layer can have different color and/or composition
-determined using microscopic analysis - chemical properties
-solubility: determine possible solvent used as binder
-pyrolysis gas chromatography
-infrared micro-spectrophotometry (FTIR)