HAIR, FIBER, AND PAINT

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Unit 3

• HAIR, FIBER, AND PAINT

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Unit 3 vocabulary

• Atom- smallest unit of matter.
• Chromatography- separation of
• chemical matters based on
• physical properties.
• Class characteristics- Properties of
• some evidence that can be associated
• with a group, but never with a single source.
• Individual characteristics- properties of
  evidence that can be attributed to a common
  single source.

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Kinds of chromatography Paper Gas
Chromatography
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Example of class characteristics All tires of a
certain brand and type are made with the same
material and have the same pattern
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Example of individual characteristics Each tire
will have a different wear pattern depending on
the car and driver
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Cont.

• Comparison- trying to ascertain whether two or
  more objects have a common origin.
• Crystalline solid- a solid in which the atoms
  have formed a regular/patterned arrangement.
• Density- mass per unit of volume
• Standard/reference sample- physical evidence in
  which the origin is know to be used to compare
  to crime scene evidence.
• Substrate control- uncontaminated surface
  material close to an area where physical evidence
  has been deposited used to ensure that a surface
  is not contaminated.

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A Crystalline solid
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STANDARD SAMPLE OF A KNOWN FIBER
FIBER FROM THE CRIME SCENE
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Hair Evidence      Hair evidence found at
crime scenes has helped tremendously in the past
with solving many criminal cases. Hair evidence
has been used to establish its origin, and
whether or not the hair retrieved at the crime
scene compares with hair that is known to have
come from a particular individual. The
distinction between animal hair and human hair is
easily seen.
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HUMAN HAIRS
DOG HAIR
CAT HAIR
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FIBER IDENTIFICATION Natural fibers Cotton is
a plant fiber. Linen is also a plant fiber but
different from cotton in that the individual
plant fibers which make up the yarn are long
where cotton fibers are short. Silk is a
protein fiber from spiders. Wool is also a
protein fiber but the individual "hair" fibers
are shorter than silk and the weave of the
fabrics is generally looser than with silk.
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Man Made Fibers Acetate is made from cellulose
(wood fibers). Acrylic is made from natural gas
and petroleum. Nylon is a polyamide made from
petroleum. Polyester is a polymer produced from
coal, air, water, and petroleum products. Rayon
is a regenerated cellulose fiber which is almost
pure cellulose. Blends consist of two or more
fibers and, ideally, are supposed to take on the
characteristics of each fiber in the blend.
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Paints Many types based on base of paint-
what is the basic chemical(s) that make up the
point use of paint pigments used to color
paint durability of paint