Examination of Paint Examine two paint samples to determine same origin Generally used in burglaries, hit-and-run accidents or vehicle accidents

Composition of Paint Paint is composed of a binder, pigments and additives dissolved in a solvent Paint is spread onto a surface and dries in a hard film As it dries, the solvent evaporates leaving behind the binder and pigments suspended in it

Automotive Paint Layers Electrocoat primer: applied to steel body to prevent corrosion, generally gray or black Primer Surfacer: Completely smoothes out surface. Highly pigmented to minimize difference in color between basecoat and primer

Automotive Paint Layers, cont’d Basecoat: Provides the color and finish of the car. Must be able to resist UV rays, weather and acid rain. Clearcoat: Un-pigmented layer used to improve gloss and durability of the paint

Examination of Paint Color determination is used to identify paint Two paint samples would be examined under stereoscopic microscope for color, surface texture and color layer sequence An increase in the complexity of the layer structure gives a sample greater forensic value

Examination of Paint, cont’d Use pyrolysis gas chromatography to determine paint formulation IR Spectrophotometry is used to determine composition of paint Analyze the inorganic pigments in paint using neutron activation analysis, X-ray diffraction and X-ray spectroscopy. Compare paint make-up to color charts maintained by car manufacturers to determine make and year of car

Collection and Preservation of Paint Evidence Pick up with forceps or scooped up with paper Use druggist folds or glass vials to contain paint Collect standard/reference sample when available using clean scalpel or Exacto Knife