RESULTS
The visualized minutiae in each glue-coated fingerprint recovered from each of the four different substrate types (plastic, polymer, tile and wood) were analyzed by AFIS and the results are presented as the % maximal coverage in Table 1 and Fig. 2. With a few exceptions, the details of the ridges in the control (uncoated) prints could not be identified at all, and even these exceptions were so poor (only 2.6 – 7.7% of minutiae being resolved) as to be of no real forensic use. With a few exceptions the best results were obtained after drying with a hair dryer, which is logistically an advantage allowing quick processing times, especially in crime scenes that are unstable / unsafe or where many prints are required to be taken. For those exceptions, where better prints were obtained after air drying for 60 min or 1 day, either better quality prints could be obtained with a different glue dried by the hair dryer (Polymer N and OC vs. ST; Plastic PM vs. N and B) or almost as good results could be obtained (Wood N and OC). Thus, overall, with the correct glue-substrate sample matching, drying by hair dryer is optimal. As to the optimal combinations, from Table 1 the best resolution was obtained with ST for polymer and tiles, OC for wood and U for plastic. With respect to the substrate surfaces, most of the highest quality print images were obtained from the plastic surface using a hair dryer, whilst prints from tiles were typically the worst, except for wood and glue ST (Tables 1 and 2; Fig. 2). With respect to the glues, each glue and drying condition was suitable, although not necessarily optimal, for at least surface (Tables 1 and 2). As already mentioned, the best glue – drying combination for recovery of latent prints from each of the four substrate surfaces was not Tex-Lift in all cases. Indeed, the best quality prints on all four types of rough surface from the eight experimental glues were higher than those from Tex-Lift. The results showed that UHU was good for plastic when dried by a hair dryer, tiles and wood when air-dried for 60 min. OC with air-drying for 60 min and ST when dried by a hair drier were suitable for polymer. ST with a hair dryer and U when air-dried for 60 min were both good for tiles. B and OC with a hair dryer, and H and U when air-dried for 60 min, were good for lifting prints from wood. For Tex-Lift, the best quality print was seen on polymer under a hair dryer (Tables 1 and 2).