Deck 11: Chemical Processing Methods: Porous Substrates

Question 1

What is the definition of a porous substrate?

Answer 1

a. Any substrate permeable to liquids and gases
b. Materials containing pores

Question 2

List three examples of porous substrates.

Answer 2

a. Paper
b. Cardboard
c. Wood

Question 3

What happens when a latent print is deposited on a porous surface?

Answer 3

a. The latent print residues permeate the fibers
b. The water-soluble components of the fingerprint residue (amino acids, sodium chloride, urea, etc.) are absorbed into the surface, while the non water soluble components (lipids, waxy compounds, etc.) sit on the surface until they are wiped away or destroyed by environmental factors
c. While the water evaporates, the other components remain embedded in the fibers

Question 4

Which component of latent print residues bind strongly to the cellulose fibers and are developed by chemical reagents?

Question 5

fingerprints on porous items developed with chemical reagents may be both visible and florescent.

Question 6

Why is it important to use the chemical reagents in a particular sequence?

Question 7

What is the recommended processing sequence for processing porous items for fingerprints?

Question 8

What is the name of the compound produced when ninhydrin reacts with amino acids?

Question 9

What does ninhydrin react with in the fingerprint residues?

Question 10

How is ninhydrin applied to porous items?

Question 11

Which carrier solvent for ninhydrin has both of the following qualities: inflammability and low toxicity.

Question 12

heat and humidity are used to speed up the development process when a porous item is treated with ninhydrin.

Question 13

Which chemical reagent develops highly fluorescent fingerprints when applied to a porous item?

Question 14

What is the process for developing an item with DFO?

Question 15

At what wavelengths are DFO developed items visualized? What color barrier filter is used to visualize DFO developed items?

Question 16

Which chemical processing method is most successful for developing fingerprints on porous items?

Question 17

Name the three chemical reagents that react with amino acids on porous items?

Question 18

What is the process for developing an item with 1,2-indanedione?

Question 19

At what wavelength are 1,2-indanedione developed items visualized? What color barrier filter is used to visualize 1,2-indanedione developed items?

Question 20

1,2-indanedione processed fingerprints result in a fluorescent product.

Question 21

In what situation is physical developer the preferable method for processing porous items?

Question 22

What compound in fingerprint residue does physical developer react with?