The Pabst's method: An effective and low-budget tool for the forensic comparison of opaque thermoplastics - Part 1: Additional discrimination of black electrical tapes

For many years now, Pabst's micro-press has been used in German forensic science laboratories as a valuable addition to methods of comparative analysis of plastic trace evidence. However, it is as yet hardly known in laboratories outside of Germany. The principal reproducibility is demonstrated by a homogeneity check of a raw backing material of defined origin. The illustrated results of a proficiency test emphasise the applicability of the Pabst method for forensic comparisons. The discrimination power of the Pabst method was tested by taking 90 black PVC-backings provided by the FBI Laboratory, i.e. those that could not be discriminated by standard methods. In this way further discriminations could be achieved. In the following, the Pabst method is therefore introduced as a straightforward, inexpensive and useful tool.