Forensics - paint
- Created by: Ashlee
- Created on: 28-04-15 14:41
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- Paint
- Road traffic collision; burglary
- pigment; solvent & binder
- pigment = finely ground, insoluble particle
- colour
- durability
- hardness
- binder = non-volatile liquid which binds pigment particles together
- pigment = finely ground, insoluble particle
- organic & inorganic
- water & oil based
- primary pigments
- white = titanium dioxide
- black = carbon
- brown/red = iron oxide
- orange = cadmium sulfide
- green = chromium oxide
- blue & green = organic compounds
- oil based paints
- spread paints and solvent evaporates
- solvent = mix of hydrocarbons
- water based paints
- solvent = water
- binder polymerises and hardens as dries
- forms film and holds to surface
- automobile paint
- complex
- 1) electrocoat primer for corrosion resistence
- 2) primer surface for smoothness
- 3) basecoat for enriched colour
- 4) clear coat for protection
- 3) basecoat for enriched colour
- 2) primer surface for smoothness
- collection
- nature of interaction/ease of exchange
- seize whole item where possible
- large flecks with tweezers
- take control sample
- small flakes 1cm squared scraped onto paper
- analysis
- microscope
- size & shape
- surface condition
- colour
- layer sequence
- thickness
- probative value
- non-destructive
- further analysis
- chemical reactions
- fluorescence microscopy
- infrared microspectrophotometry
- scanning electron microscopy with x-ray microanalysis
- destructive
- microscope
- forensic value
- links object to crime scene
- links object to victim
- physical matches - evidence of original source
- analysis = make/model/year of automobile
- analysis = layers provide strong evidence of original source
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