What type of reagent is Physical Developer (PD)?

Physical Developer (PD) is classified as a silver-based reagent. This means it employs silver compounds to visualize latent prints on porous surfaces. The process involves a chemical reaction where the silver is reduced to metallic silver, allowing for the development of the latent prints.

Silver-based reagents are particularly useful because they can enhance prints that have been contaminated by moisture, making them effective for developing fingerprints on absorbent materials like paper or cardboard, which often absorb oils and moisture from the fingers. This characteristic differentiates it from other reagent types, which may not have the same effectiveness on porous substrates.

In contrast, aqueous-based reagents are water-soluble and are typically used in different contexts for latent print development, while powder-based reagents utilize physical adhesion and are suited for non-porous surfaces. Gas-based reagents, while they can also be employed in forensic applications, work through different mechanisms and are not relevant to the properties and functions of Physical Developer. Thus, identifying Physical Developer as a silver-based reagent highlights its specific methodology and application in latent print development.