Module 23 / 24 - Fingerprints

Porous substrate

Surface that absorb moisture

Nonporous substrate

Surface that does not absorb moisture

Semi porous substrate

May resist and absorb fingerprint residue

Cyanoacrylate fuming

Used to develop latent prints on nonporous and semi porous surfaces

Traditional cyanoacrylate fuming pros

Greater buildup of ridge detail

Easier to see without post processing

Better visualization under FSIS

Shorter fuming time

Traditional cyanoacrylate fuming Cons

Item must be fully hung and opened up

Greater possibility of over fuming

Sometimes heavy development on background

Vacuum cyanoacrylate fuming

At reduced pressure the evaporation of cyanoacrylate is accelerated and development time is reduced (chamber stays at approx 20Hg)

Vacuum CA Pros

Prints show sharper ridge and pore detail

Don’t have to hang items they will be fully fumed

Lack of background development - improves overall contrast after treating with a stain

Vacuum CA Cons

Prints tend to be translucent and weakly visible to naked eye

Bottle / cans must be open due to pressure

Dye stains

Basic red, Ardrox, Basic yellow, Rhodamine 6G, RAY