Which agent is primarily used in treating wet non-porous surfaces for latent prints?

The Small Particle Reagent is primarily used for developing latent prints on wet non-porous surfaces due to its ability to adhere to moisture present in the latent print residue. This agent is composed of very fine particles that can bind to fingerprint oils and sweat, making the prints visible when they dry. Its effectiveness in this context arises from its capability to interact with the components of the latent print, even when the surface is wet, allowing investigators to successfully recover prints that might otherwise be difficult to visualize.

In contrast, while other agents like Sudan Black and Ninhydrin are valuable for different types of surfaces and conditions, they are not specifically formulated for wet conditions on non-porous surfaces. Sudan Black, for example, is typically used on porous surfaces and relies on a different process to develop prints, whereas Ninhydrin primarily reacts with amino acids in sweat and is most effective on porous materials such as paper. Superglue, or cyanoacrylate, is generally utilized to visualize prints on non-porous surfaces, but it is not ideal for wet conditions as it requires a dry surface to create a durable impression of the latent print.