Patent fingerprints are made by a liquid or
powder that sticks to the finger and then
transfers to a surface, leaving an easily
visible fingerprint behind. Substances that can
leave patent fingerprints are ink, blood, dirt,
flour, grease, etc. When police take inked
fingerprints, they are collecting patent
Plastic fingerprints are 3D impressions of
fingerprints left in a substance like wax, mud,
paint, soap, tar, drying blood, etc. They are
generally easily visible.
A good way to think of the difference is that
an impression of a fingerprint left in blood is
a plastic fingerprint, but a fingerprint of
blood residue transferred to another surface is
a patent fingerprint.
First, both types of prints are generally
photographed since they are visible to the naked
eye without enhancement. Different photography
techniques can help to make the prints more
visible in the photographs.
After photographing, patent prints are
processed or lifted from the surface much as a
latent (invisible) fingerprint would be. See
to learn more about preserving latent
Plastic fingerprints are generally preserved
by casting. A liquid material (silicone rubber,
plaster, or a metal alloy) is poured over the
fingerprint and hardened to make a cast of the
impression. The cast is much more durable than
the plastic fingerprint and can be stored as
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