Fingerprints deposited on PMMA substrates were used in these experiments. Non-fluorescing PMMA substrates were chosen for optimisation and lifetime study of fingerprints treated with fluorescent powders. Non-fluorescing substrates were chosen to avoid the overlapping of background fluor-escence with that of treated fingerprints. Later, fluorescing PMMA substrates were used in the TR imaging experiments. Fluorescent powder was applied by means of a magnetic brush onto the latent fingerprint samples. Generally, these types of powders are most effective to develop the prints on non-porous surfaces. Care was taken to apply the powder almost uniformly onto fingerprint samples. The powders