Sources & Types of Fiber

Fibers are everywhere Fibers are everywhere Textiles are mass produced so difficult to trace a fiber to a specific source Textiles are mass produced so difficult to trace a fiber to a specific source Statistics & probability are important for narrowing source Statistics & probability are important for narrowing source Fiber evidence is valuable because it can link victims, suspects, & places together Fiber evidence is valuable because it can link victims, suspects, & places together Investigators identify & compare fibers physically & chemically Investigators identify & compare fibers physically & chemically

Considered class evidence Considered class evidence Usually unable to individualize Usually unable to individualize Fibers are mass-produced in huge quantities Fibers are mass-produced in huge quantities Have probative value Have probative value Can be used to create connections or associations Can be used to create connections or associations Are common trace evidence at a crime scene Are common trace evidence at a crime scene Along with hair, most common type of physical evidence Along with hair, most common type of physical evidence

More valuable as evidence when any characteristic can limit number of sources More valuable as evidence when any characteristic can limit number of sources The more properties found similar between suspect & known fibers, the stronger the case The more properties found similar between suspect & known fibers, the stronger the case One inconsistency or property that doesn’t match, negates association One inconsistency or property that doesn’t match, negates association Investigators generally must perform many tests to identify & compare fiber evidence Investigators generally must perform many tests to identify & compare fiber evidence

Fabric is made of fibers Fabric is made of fibers Fibers are made of twisted filaments Fibers are made of twisted filaments Types of fibers and fabric: Types of fibers and fabric: Natural Natural Animal, vegetable, or inorganic Animal, vegetable, or inorganic Artificial Artificial Synthesized or created from altered natural sources Synthesized or created from altered natural sources

SyntheticRayonNylonAcetateAcrylicSpandexPolyester NaturalSilkCottonWoolMohairCashmere

Fibers are used to make Fibers are used to make Textiles Textiles Cloth or carpeting Cloth or carpeting Cordage Cordage Rope, string, nets Rope, string, nets Filling materials Filling materials Mattresses, pillows, upholstery Mattresses, pillows, upholstery Optical cables Optical cables Structural materials Structural materials Used in cars, tires, & airp lanes Used in cars, tires, & airp lanes

Fibers used to make fabric Fibers used to make fabric Each fabric has its own characteristics Each fabric has its own characteristics Most fabrics made by weaving fibers Most fabrics made by weaving fibers Also by knitting, crochet, macrame, braiding, netting, & felting Also by knitting, crochet, macrame, braiding, netting, & felting Three basic weave patterns Three basic weave patterns:

In woven fabric In woven fabric Warp is lengthwise yarn Warp is lengthwise yarn Stronger, smoother, & tighter twist than weft Stronger, smoother, & tighter twist than weft Weft is crosswise yarn Weft is crosswise yarn Warp & weft isn’t always same material or color Warp & weft isn’t always same material or color Called a blend Called a blend Warp & weft may be different diameters Warp & weft may be different diameters Gives ribbing effect Gives ribbing effect

Natural fibers are classified according to their origin: Vegetable or cellulose Vegetable or cellulose Animal or protein Animal or protein Mineral Mineral

Cotton Cotton Vegetable fiber Vegetable fiber Strong, tough, flexible & moisture-absorbent Strong, tough, flexible & moisture-absorbent Does not retain shape Does not retain shape Rayon Rayon Chemically altered cellulose Chemically altered cellulose Soft, shiny & versatile Soft, shiny & versatile Cellulose acetate Cellulose acetate Chemically altered cellulose Chemically altered cellulose Created compound not found in nature Created compound not found in nature

Can you see the difference between cotton on the left and rayon on the right?

Wool Wool Insulating & dries quickly Insulating & dries quickly Animal fiber most often from sheep Animal fiber most often from sheep Other sources Other sources Goat = mohair Goat = mohair Rabbit = angora Rabbit = angora Camel, alpaca, llama Camel, alpaca, llama Silk Silk Insect fiber spun by silkworm to make cocoon Insect fiber spun by silkworm to make cocoon Insulating & reflects light Insulating & reflects light

Asbestos Asbestos Natural fiber Natural fiber Used in fire-resistant substances Used in fire-resistant substances Rock Wool Rock Wool Man-made mineral fiber Man-made mineral fiber Used for insulation, seed pots, etc Used for insulation, seed pots, etc Fiberglass Fiberglass Man-made inorganic fiber Man-made inorganic fiber Used for insulation, car bodies, bathroom fixtures, etc Used for insulation, car bodies, bathroom fixtures, etc

Made from derivatives of petroleum, coal & natural gas Made from derivatives of petroleum, coal & natural gas Nylon Nylon Most durable of man-made fibers Most durable of man-made fibers Extremely lightweight Extremely lightweight Polyester Polyester Most widely used man-made fiber Most widely used man-made fiber Acrylic Acrylic Lightweight, soft & resilient fiber Lightweight, soft & resilient fiber Provides warmth Provides warmth Spandex Spandex Extreme elastic properties Extreme elastic properties