Gentian violet is effective for developing latent fingerprints on which type of surface?

Gentian violet is particularly effective for developing latent fingerprints on adhesive surfaces, such as those found on adhesive tapes. This is largely due to gentian violet's ability to adhere well to the moisture and oils present in fingerprints, which can be particularly prominent on these kinds of surfaces. When applied, it reacts with the components of the latent prints and can enhance the visibility of the prints against the sticky background of the tape.

On other surfaces, such as metal, paper, or plastic, gentian violet is not as effective. Metal surfaces may not allow the dye to adhere as well without additional treatments, while paper can absorb the dye unevenly, preventing sufficient development of the prints. Plastic surfaces often require different types of reagents or techniques, like powdering or cyanoacrylate fuming, to develop latent prints effectively. This specificity makes gentian violet a useful tool specifically for adhesive surfaces in forensic work.