All experimental data presented in this report were obtained by undergraduate and first year graduate students, who also played a very active role in planning the experimental work, interpreting/discussing the results and reflecting on various ways further experiments can be carried out. One outcome of such discussions was the examination of overlapping ink marks to establish the order in which various handwritten entries have been made (Figures 2C) and examination of mixed documents by establishing the pen over print vs. print over pen layers ordering (Figure ). Another suggestion that resulted from these discussions related to the possibility of building a database of commercial inkjet inks (using both brand names and aftermarket products), similar to the extensive database of writing inks maintained by the U.S.