Flake Metal Powders for Revealing Latent Fingerprints

Abstract Fine flake powders, having flake diameters ranging from 50 to 1 μm and stearic acid/powder ratios varying from 0 to 50 weight percent, were produced by laboratory-scale milling of aluminum, zinc, copper, and iron powders. The effectiveness of these flakes for detection of latent fingerprints was then assessed by comparing the print qualities obtained when using these flake powders with those achieved using commercial aluminum, commercial black, and commercial dark magnetic dusting powders. While the commercial aluminum powder was found to have an average flake diameter and stearic acid level close to the optimum values required to obtain bright fingerprints, several potential avenues of development were identified which could lead to the commercial availability of superior black powders.