Polymerization of the volatile sulfur nitride S<sub>2</sub>N<sub>2</sub> can be brought about by interaction with latent fingerprint residues,
with the resulting dark blue black polymer (SN)x visually developing the prints on a large range of media. Consideration
of the technical and safety requirements of the technique allows an effective apparatus to be built and utilized with
minimal risk. Observations on the diversity of media involved highlights the power of the technique, though results also
indicate that no simple mechanism can account for all aspects of the interactions between the nitride, the prints and the
media surfaces. This is especially apparent when prints on paper or plastic can still be imaged after washing with either
water or organic solvents; likewise prints on aluminium foil can be imaged even after being heated to 500°C overnight.