What is the optimum relative humidity for developing ninhydrin-treated latent prints?

The optimum relative humidity for developing ninhydrin-treated latent prints is determined by the need for a specific environment that enhances the chemical reaction between ninhydrin and amino acids present in the latent prints. Relative humidity levels of 65-80% provide the ideal conditions for ninhydrin to react effectively, facilitating the visualization of latent prints.

In this humidity range, the moisture content in the air aids in the development process by promoting better absorption of ninhydrin and improving the reaction kinetics. This leads to sharper and more distinct print development, increasing the chances of successful visualization and subsequent analysis.

Humidity levels below this range might not provide sufficient moisture for optimal reaction, resulting in less effective print development, while extremely high humidity levels could cause oversaturation, which may negatively impact the clarity and resolution of the resulting prints.