NCJ Number
146639
Journal
Journal of Forensic Sciences Volume: 39 Issue: 1 Dated: (January 1994) Pages: 15-20
Date Published
1994
Length
6 pages
Annotation
A systematic evaluation of the effect of humidity on electrostatic detection apparatus (ESDA) images showed that the quality of ESDA images depended on changes in the water content of paper which occurred during the period between indentations and paper examination rather than on the water content of paper at the time indentations were made.
Abstract
Techniques were devised for producing standardized impressions in order to compare ESDA results under different conditions. Standard impressions were produced by affixing various weights (100, 200, 300, 400, and 500 g) to the end of a writing instrument. These weights simulated varying pen pressures used by different individuals when writing. Without applying any downward pressure, the weighted writing instrument was held between the fingers of the writing hand and moved across the surface of the top sheet of a stack of pages to produce a drawing. A rating scale for developed impressions was used to quantify ESDA results. The best quality ESDA results were obtained at the time indentations were made. Changes in the water content of paper which occurred after indentations were made but before the paper was examined had a more significant influence on the quality of ESDA results than did paper condition at the time indentations were made. Techniques that may provide optimum ESDA results in other environments are described, and quality assurance procedures are noted. 8 references, 1 table, and 3 figures