Physical methods for examining and comparing transparent plastic bags and cling films

Stable isotope ratio mass spectrometry and physical comparison for the forensic examination of grip-seal plastic bags

“…Previous research has examined a range of physical and spectroscopic techniques for the classification of plastic films but, in general, has focused on the characterisation of production and handling marks [8][9][10][11][12][13][14]. Although the marks left on extruded plastic by machines are often visible with no enhancement it is generally accepted that birefringence patterns have greater potential for characterising clear plastics as more detail can often be seen using polarising filters [10].…”

Forensic examination of plastic drinking straws based on their physical characteristics and manufacturing marks

“…There were, nevertheless, packets of straws that cannot be discriminated based on their polarizing patterns alone. As the examination of manufacturing marks is known to be useful when comparing plastic bags [11,13,14,17], we hypothesized that comparison microscopy of manufacturing marks that were left on the straws during the extrusion process (notably, toolmarks left by the die, pullers, and sizing plates) will similarly be useful.…”

“…To the best of our knowledge, while the forensic examinations of other drug packaging materialssuch as plastic bags [11][12][13][14][15][16][17], packaging films [17,18], newspapers [19,20], and adhesive tapes [21][22][23][24][25][26][27]had been reported, corresponding studies of drinking straws have not been done. We thus compared the physical characteristics and manufacturing marks of drinking straws from various commercial sources available in Singapore to evaluate their discriminatory values, as well as to gain a better understanding of typical internal variations that might be encountered.…”

Plastic Film Examinations

“…Castle et al (1994) gives more detail about the production and comparison techniques used for transparent plastic bags and wrapping film. In some cases a writing strip or printing is applied to the surface of the bag.…”