FORENSIC CHEMISTRY LABORATORY MANUAL

by R.Q. Thompson; Oberlin College

MICROSCOPIC AND SPECTRAL ANALYSIS OF PAINT CHIPS

Objective

To characterize and compare paint chips by color and composition.

 

Sample

A variety of automotive paint chips, some of similar color. Find a junk yard and obtain samples from automobiles whose paint is peeling. Store the chips in plastic bags, and assign chips to each suspect and to the crime scene.

 

Reagents

None

 

Standard Reference Material

 

None

 

Methods

Optical microscopy (structure, layers)

Visible, diffuse reflectance spectrophotometry (color)

Infrared, diffuse reflectance spectrophotometry (composition of resin coating)

 

Special equipment

Optical microscope, Visible spectrophotometer with diffuse reflectance accessory ; FT-infrared spectrophotometer with diffuse reflectance accessory

 

Procedure

For instructor (detailed); For student (brief)

 

Typical results

Visible reflectance spectra of red and blue paints ; Infrared reflectance spectra of red and blue paints ; Description of the results.