chapter  11
14 Pages

Chemical Processing Methods

Porous Substrates
ByHillary Moses Daluz

Porous items are substrates permeable to liquids and gases such as paper or cardboard. Porous substrates absorb latent print residues. The water-soluble components of the fingerprint residue are absorbed into the surface and the non-water-soluble components remain on the surface unless they are obliterated. Sequential processing with chemical reagents is used to develop both visible and fluorescent prints. This text addresses the most common porous processing reagents: indanedione, DFO, ninhydrin, and physical developer. Indanedione, DFO, and ninhydrin react with amino acids while physical developer reacts with sebaceous deposits.