FORENSIC CHEMISTRY LABORATORY MANUAL

by R.Q. Thompson; Oberlin College

COMPOSITION AND COLOR ANALYSIS OF FABRIC SAMPLES

Objective

To compare the color and composition of fabric samples.

 

Sample

Use pieces of cotton/polyester fabric of similar color but different composition. Fabric samples should be torn from the stock fabric so that fraying and stretching are evident. Size samples so they are just large enough to fill the sample holders. Pieces of fabric evidence should be stored separately in labeled, sealed bags. Assign small pieces to the crime scene and the suspects.

 

Reagents

Provide students with three or four fabric samples with known percentages of cotton and polyester covering the range from about 40% polyester to 100% polyester.

 

Standard Reference Material

 

None
Methods

Visible, diffuse reflectance spectrophotometry (color)

Fourier Transform Raman spectrophotometery (composition)

 

Special equipment

Visible spectrophotometer with diffuse reflectance accessory ; FT-Raman spectrophotometer

 

Procedure

For instructor (detailed); For student (brief)

 

Typical results

Diffuse reflectance visible spectra of pink & green fabrics

FT-Raman spectra of pink & green fabrics

 

Alternate Method

FT-Infrared with ATR accessory (composition)

 

Procedure

 

(planned for the next edition)