The effectiveness of natural indigo/kaolinite composite powder in the development of latent fingermarks

Composites are materials that have multiple phases and have attracted much attention as they are able to improve physical and chemical properties of an isolated material. In this sense, these composites are commonly used as key components for two purposes: coloring and improving the operational properties; besides that, they have alternative synthesis routes that respect the principles of green chemistry. Thus, this reports the development of a new composite using natural products, indigo and kaolinite, for application in papilloscopy as a new nontoxic fingermark developer. The composite was obtained via green procedures and was characterized by spectroscopic and chromatographic techniques. Thus, to investigate the potential of the material as a fingermark developer, different techniques were applied such as depletion, aging, comparison with commercial powder, and development of latent fingermarks on different surfaces. Tests revealed that the composite presented good contrast and adhesion with the latent fingermarks, even after 15 days of deposition. This study presents a natural indigo/kaolinite composite powder that showed similar or higher efficiency when compared to the commercial fingerprint powder and was able to develop identifiable natural and sebaceous fingermarks. • A composite was formed from eco-friendly materials. • The composite formation follows the concepts of green chemistry and low cost. •The composite was applied as a latent fingermark developer.