National Center for Forensic Science

Glass

Forensic analysis of glass consists of the examination of two or more fragments to determine whether they have a common origin.  Identifying broken glass fragments having a common source to the exclusion of all other sources may only be done if they can be physically matched together.

Submitted samples from a crime scene must first be confirmed as glass.  Differentiating glass from plastic is done by examining relative hardness, solubility, and observation with a polarized light microscope.  Once confirmed as glass, the examiner will perform an analysis of physical properties (color, fluorescence, thickness, curvature, density), optical properties (Refractive Index) and chemical composition.  If a difference between questioned and known samples is found at any point in this process  no further comparison is needed.

Reference: Scientific Working Group on Materials Analysis, “Initial Examinations of Glass”, http://media.wix.com/ugd/4344b0_292c63e8448a46eb84252b6e62603680.pdf, July 2004, accessed March 10, 2016.

NCFS research:

1.Characterization of float glass by laser-induced breakdown spectroscopy (LIBS)

2.Forensic comparison of glass by laser-induced breakdown spectroscopy (LIBS)

3.Comparison of float glass by application of chemometrics to LIBS data.

For more information contact Dr. Michael Sigman and Dr. Matthieu Baudelet.