What color does Small Particle Reagent typically develop on a fingerprint?

Small Particle Reagent (SPR) is specifically designed to visualize fingerprints on non-porous surfaces, particularly when other methods may not yield clear results. This technique leverages the properties of the reagent to adhere to the lipids and moisture present in fingerprints. When SPR is applied, it typically develops a gray color as the particles bind to the fingerprint components and reflect light. This gray coloration results in a contrast that allows the latent prints to become visible for further examination and analysis.

The gray color is particularly advantageous because it can enhance the visibility of the fingerprint patterns under various lighting conditions, which is crucial in forensic examinations. Other colors, like brown, clear, or red, would not be typical for SPR and may imply different techniques or reagents that do not specifically highlight latent prints in the same effective manner as the gray development achieved by Small Particle Reagent.