Volume 41, Issue 1 (January 1996)
pH Indicators As Chemical Reagents for the Enhancement of Footwear Marks
Enhancement of weak two-dimensional shoemarks is often necessary due to the poor image detail. Thiocyanate is regarded in the literature as the most effective reagent for the chemical enhancement of footwear marks. In this study we have examined the possibility of using pH indicators, Bromophenol Blue and Bromocresol Green, as chemical reagents for the enhancement of footwear marks. The performance of these reagents on various surfaces, such as plastic sheets, brown paper, cardboard, porcelain bathroom tiles and cotton cloth, was compared to that of the thiocyanate reagent. It was found that these reagents were much more effective than ammonium thiocyanate for the samples of shoeprints in various regions of Israel. The mechanism of chemical enhancement of footwear marks by these reagents was elucidated. A solution of 1% Bromophenol Blue and 5% of water in methanol was chosen as the Bromophenol Blue formulation in this laboratory for the chemical enhancement of shoeprints.