Evaluation of the solvent black 3 fingermark enhancement reagent: Part 1 — Investigation of fundamental interactions and comparisons with other lipid-specific reagents

The fundamental interactions between sebaceous constituents of fingermarks and three lipid specific fingermark enhancement reagents (solvent black 3, basic violet 3 and basic violet 2) are reported. The staining of fingermarks is investigated using optical microscopy, and the interaction of the reagents with individual constituents is explored using spot tests. It is demonstrated that solvent black 3, basic violet 3 and basic violet 2 all interact with different constituents of sebaceous sweat, and this may offer potential for using the reagents in sequence for fingermark enhancement. Further tests to explore the effect of dye concentration on reagent effectiveness indicate that dye concentration can be reduced by up to 25% without significant detriment to effectiveness. It is shown that there is little practical difference between solvent black 3 formulations with the solvents (ethanol and 1-methoxy-2-propanol) used in this study. The study also indicates that basic violet 2 may have some operational advantages over basic violet 3 and may be worthy of further investigation.