Chemical Processing Methods : Nonporous Substrates
Nonporous substrates such as metal, glass, or plastic are impermeable to gases and liquids. They do not absorb fingerprint residues as porous substrates do. Instead, latent prints sit on the surface of a nonporous item and are subject to environmental effects such as wind, rain, temperature, and humidity. As with porous substrates, a majority of the water component of eccrine sweat evaporates over time. Because the fingerprints remain on the surface, nonporous items should be handled with great care on heavily textured or rough surfaces or on the edges so as not to rub off any latents on the smooth surfaces.