Chemical Processing Methods
Nonporous surfaces are substrates that are impermeable to liquids and gases such as metal, plastic, and glass. Latent prints deposited on nonporous substrates remain on the surface of the item and are thus vulnerable to obliteration by environmental factors. Cyanoacrylate (superglue®) fuming fixes latent prints to a surface to make them more durable and visible. Aqueous superglue is vaporized in a fuming chamber and polymerizes along the latent friction ridges forming a three-dimensional white print. As white prints are difficult to visualize, fluorescent dye stains are applied to enhance contrast. This text examines the most common dye stains: rhodamine 6G, Ardrox, MBD, and Basic Yellow 40. Vacuum metal deposition, multi metal deposition, and single-metal deposition are also addressed.