What is the optimum relative humidity percentage for post-processing ninhydrin-treated latent prints?

The optimum relative humidity percentage for post-processing ninhydrin-treated latent prints is indeed within the range of 65-80 percent. This level of humidity is crucial for developing the color reaction that ninhydrin produces when it reacts with amino acids present in latent fingerprints. Ninhydrin reacts more effectively at higher humidity levels because the water vapor in the air aids in the diffusion of ninhydrin on the print surface, allowing for better interaction with the residues. This results in more vivid and easily detectable print patterns, facilitating clearer visualization and analysis.

Humidity levels below this optimum range may lead to incomplete development or faded prints, while levels exceeding this range could result in overdevelopment, which can also obscure details. Thus, maintaining humidity levels between 65-80 percent is essential for achieving the best results in latent print enhancement with ninhydrin.