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.