NCJ Number
85730
Date Published
1982
Length
8 pages
Annotation
This paper gives the fire investigator a basic understanding of what glass is made of, how it is manufactured, and what it can tell the investigator (in terms of evidence).
Abstract
Most glass today consists of variations of mixtures of silica, lime, and soda. There are many specialty glasses manufactured. Most glass objects will soften at approximately 1,000 degrees F and flow at about 1,300 degrees F. Light bulbs, which bulge and point toward the heat source or blow out toward the heat source when melting, can be of great help in locating the fire's point of origin. The color and density of smoke on glass surfaces and in various locations within the fire area can also be clues as to fire location. Window glass fragments with large cracks due to heat and heavy smoke deposits usually indicate either slowly developing fires or a position of relative distance from the point of origin. Fire investigators should also look for other melted objects that point to the area of greatest heat, such as a candle, parts of plastic ornaments, etc. To determine whether arson was committed, the investigator should examine glass fragments at the scene to see if forced entry was made; this involves reconstructing the window with the glass fragments. A glossary of terms (with illustrations), footnotes, and 11 references are provided.