NCJ Number
215688
Journal
Journal of Forensic Identification Volume: 56 Issue: 5 Dated: September-October 2006 Pages: 769-808
Date Published
September 2006
Length
40 pages
Annotation
This study compared Traxtone and Crime-Cast, two relatively new dental stone products, with Castone (a basic raw dental stone product traditionally used for crime-scene casts) in terms of their ability to cast impressions in sand and soil.
Abstract
The study found that although Traxtone and Crime-Cast do produce detailed casts of shoe and tire impressions, the authors recommend using Castone, the traditional casting material, because bulk dental stone provides more flexibility in the size and amount required at the crime scene. It is also readily available from many dental suppliers, thus affording greater purchase accessibility. It costs less than Traxtone and Crime-Cast and sets up quickly. Casts were made with each of the products in a variety of temperatures in Alaska and Florida. The descriptions of materials and methods addresses the characteristics of gypsum and plasters, powder-to-water ratio and consistency, the weighing of a portion of dental stone for placement into a ziplock bag for carrying to crime scenes, the use of casting forms, the use of extra water in casting, and drying before cleaning the cast. Also discussed are compression strength in crime-scene applications, the expansion of casting materials when they set, release agents and fixatives, and pouring methods for footwear impressions. In describing the field study and evaluation of casting materials, this paper specifies the features of Traxtone and Crime-Cast; compares the cost of the three materials; evaluates their performance; describes procedures for mixing and pouring the materials; and discusses the time to set, appearance of casts and details recorded, and a comparison of compression strength and expansion. 11 figures, 1 reference, and appended SWGTREAD guides for minimum qualifications and training for a forensic footwear and/or tire tread examiner and procedures for making crime-scene footwear and tire impressions