Which latent print development technique is effective on non-porous surfaces?

The correct answer is that none of the listed techniques are specifically effective on non-porous surfaces in the way that other techniques might be.

To understand this, it’s important to consider the nature of non-porous surfaces. Non-porous surfaces, such as glass, plastic, or metal, do not absorb moisture or vapor. Techniques such as DFO (1,8-Diazafluoren-9-one) and Ninhydrin require a porous substrate to effectively interact with sweat residues. DFO is generally effective on porous materials and reacts with amino acids found in fingerprints, while Ninhydrin is mainly used on paper and other porous surfaces to react with sweat components.

Physical Developer, while it can be useful in developing latent prints, is primarily suitable for porous surfaces that have been previously treated or in instances where moisture has penetrated a porous layer and left residues that can be developed.

In contrast, techniques that work well on non-porous surfaces include cyanoacrylate fuming (superglue) which adheres to the oils and moisture in latent prints, allowing them to become visible. Therefore, for the given options, none are applicable to non-porous surfaces, confirming that the answer is