An investigation into the detection of latent fingermarks on eco-friendly soft plastics packaging

Abstract

Eco-friendly materials can present a challenge to fingermark recovery due to the variety of physical and chemical properties. Currently, there are no recommended guidelines for the recovery of latent fingermarks from eco-friendly soft plastics packaging. This work presents Phase 2 research trials for the detection of latent fingermarks on 13 different types of eco-friendly soft plastics packaging. In addition, these Phase 2 trials investigated other variables such as different fingermark donors, depletion series, ageing periods and a number of enhancement techniques that were assessed individually and in sequence with each other.The detection of latent fingermarks varied across the different substrates tested in this study and there was no specific sequence that favoured all of them. Nonetheless, sequence A (cyanoacrylate fuming - fluorescent dye staining – vacuum metal deposition) provided the highest amount of identifiable fingermarks overall. This is also the recommended sequence in the Fingermark Visualisation Manual for soft plastic packaging such as high- and low-density polyethylene plastic bags. The use of powder suspensions was the least successful across all substrates. The use of water and solvents present in certain enhancement techniques resulted in a negative effect on the structure and texture of some substrates used in this study. Statistical analysis of mark gradings from developed marks highlighted significant differences across substrates, ageing periods, donors and enhancement sequences. This work demonstrates that the current sequence in the FVM for soft plastics packaging is a good starting point for the detection of latent fingermarks on eco-friendly soft plastics packaging.