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Comparison of Fingerprint Sweat Corrosion of Different Alloys of Brass

NCJ Number
Journal of Forensic Sciences Volume: 58 Issue: 1 Dated: January 2013 Pages: 138-141
Stephanie Sykes; John W. Bond, O.B.E., D.Phil
Date Published
January 2013
4 pages
This study examined fingerprint sweat corrosion patterns on brass.
Fingerprint sweat from 40 donors was deposited onto samples of 5 x and x + B phase brasses, comprising 5 alloys with different copper and zinc concentrations, 2 of which also had the addition of small concentrations of lead. Visual grading of the visibility of the corrosion revealed that brasses with the least amount of zinc produced the most visible and fully formed fingerprints from the most donors. Consideration of previously reported mechanisms for the corrosion of brass suggests red copper (I) oxide as a likely corrosion product for low zinc brasses, and a consideration of the color, composition, and solubility of fingerprint sweat corrosion products suggests that copper (I) oxide produces good contrast and visibility with the brass substrate. Scanning electron microscope images of the corrosion of all five alloys confirmed the enhanced contrast between corroded and uncorroded areas for low zinc alloys. Abstract published by arrangement with John Wiley & Sons.