From an examination of the fingerprint sweat corrosion of 40 different individuals on phase brass, the study shows that an increase in visualization can be achieved by applying a negative potential to the brass followed by the introduction of a conducting powder. Previously, this technique has been demonstrated only for a positive applied potential and a corrosion product that was dominated by p-type copper (I) oxide. X-ray photoelectron and Auger electron spectroscopic analyses of the surface of the corroded brass show that an increase in visualization with a negative applied potential corresponds with an increase in the concentration of n-type zinc oxide relative to p-type copper (I) oxide with the Cu:Zn ratio less than 0.8:1. Work function conditions for the formation of an n-type zinc oxide/brass rectifying Schottky barrier are fulfilled. (Published Abstract)