NCJ Number
218650
Date Published
January 2005
Length
6 pages
Annotation
The Scientific Working Group for Materials Analysis presents guidelines for the determination of color, fluorescence, surface features, curvature, and thickness as they relate to forensic glass analysis.
Abstract
A general guideline is that glass color, fluorescence, surface features, curvature, and thickness can be measured by microscopic and macroscopic methods. These measurements can be used to distinguish among different glass sources. Regarding the significance and use of glass analysis, the guidelines state that at a minimum, a forensic glass examiner must identify an unknown material as glass, since many materials can be mistaken for glass. Following the identification of a material as glass, as many features as possible should be determined in order to characterize the glass and distinguish between sources. Although "sample handling" is covered in another guidelines report (see NCJ-218649), the current report offers the general advice that proper sample preparation and technique are prerequisites for obtaining reliable results in an analysis. Guidelines for the analysis of glass focus first on its appearance. This pertains to the condition of the glass and its color. Other characteristics of glass important for its analysis are fluorescence and surface features. Surface features consist of coatings, manufacturing features, and postmanufacturing surface features. Other characteristics of glass that should be considered in its analysis are curvature and thickness. The properties of glass identified through its analysis can be used to exclude fragments as originating from a given source. When the initial examinations have not excluded fragments as from a given source, then further examination is required. Documentation for a given glass sample should include the condition of the recovered fragments, approximate size, presence of original surfaces, an indication of the quantity of debris collected from various locations, and the presence of nonglass material that is potential evidence. 5 references and an 11-item bibliography