Sources & Types of FiberSources & Types of Fiber

Fibers are everywhereFibers are everywhereTextiles are mass produced so difficult Textiles are mass produced so difficult

to trace a fiber to a specific to trace a fiber to a specific sourcesourceStatistics & probability are important for Statistics & probability are important for

narrowing sourcenarrowing sourceFiber evidence is valuable because it can link Fiber evidence is valuable because it can link

victims, suspects, & places togethervictims, suspects, & places togetherInvestigators identify & compare fibers Investigators identify & compare fibers

physically & chemicallyphysically & chemically

Considered class evidenceConsidered class evidence

Usually unable to individualizeUsually unable to individualizeFibers are mass-produced in huge quantitiesFibers are mass-produced in huge quantities

Have probative valueHave probative value

Can be used to create connections or associationsCan be used to create connections or associations

Are common trace evidence at a crime sceneAre common trace evidence at a crime scene

Along with hair, most common type of physical Along with hair, most common type of physical evidenceevidence

More valuable as evidence when any More valuable as evidence when any characteristic can limit number of characteristic can limit number of sourcessources

The more properties found similar The more properties found similar between suspect & known fibers, the between suspect & known fibers, the stronger the casestronger the caseOne inconsistency or property that One inconsistency or property that

doesn’t match, negates associationdoesn’t match, negates associationInvestigators generally must perform Investigators generally must perform

many tests to identify & compare many tests to identify & compare fiber evidencefiber evidence

Fabric is made of fibers Fabric is made of fibers

Fibers are made of twisted Fibers are made of twisted filamentsfilaments

Types of fibers and fabric:Types of fibers and fabric:

NaturalNaturalAnimal, vegetable, or inorganicAnimal, vegetable, or inorganic

ArtificialArtificialSynthesized or created from Synthesized or created from

altered natural sourcesaltered natural sources

SyntheticSynthetic

RayonRayon

NylonNylon

AcetateAcetate

AcrylicAcrylic

SpandexSpandex

PolyesterPolyester

NaturalNatural

SilkSilk

CottonCotton

WoolWool

MohairMohair

CashmereCashmere

Fibers are used to make Fibers are used to make TextilesTextiles

Cloth or carpetingCloth or carpetingCordageCordage

Rope, string, netsRope, string, netsFilling materialsFilling materials

Mattresses, pillows, upholsteryMattresses, pillows, upholsteryOptical cablesOptical cablesStructural materialsStructural materials

Used in cars, tires, & airpUsed in cars, tires, & airplaneslanes

Fibers used to make fabricFibers used to make fabricEach fabric has its own characteristicsEach fabric has its own characteristicsMost fabrics made by weaving fibersMost fabrics made by weaving fibers

Also by knitting, crochet, macrame, Also by knitting, crochet, macrame, braiding, netting, & feltingbraiding, netting, & felting

Three basic weave patternsThree basic weave patterns:

In woven fabricIn woven fabricWarp is lengthwise yarnWarp is lengthwise yarn

Stronger, smoother, & tighter twist than Stronger, smoother, & tighter twist than weftweft

Weft is crosswise yarnWeft is crosswise yarn Warp & weft isn’t always same Warp & weft isn’t always same

material or color material or colorCalled a blendCalled a blend

Warp & weft may be different Warp & weft may be different diameters diametersGives ribbing effectGives ribbing effect

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

CottonCottonVegetable fiberVegetable fiberStrong, tough, flexible & moisture-absorbentStrong, tough, flexible & moisture-absorbentDoes not retain shapeDoes not retain shape

RayonRayonChemically altered celluloseChemically altered celluloseSoft, shiny & versatileSoft, shiny & versatile

Cellulose acetateCellulose acetateChemically altered celluloseChemically altered celluloseCreated compound not found in natureCreated compound not found in nature

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

WoolWoolInsulating & dries quicklyInsulating & dries quicklyAnimal fiber most often from sheepAnimal fiber most often from sheep

Other sourcesOther sourcesGoat = mohairGoat = mohairRabbit = angoraRabbit = angoraCamel, alpaca, llamaCamel, alpaca, llama

SilkSilkInsect fiber spun by silkworm to make Insect fiber spun by silkworm to make

cocooncocoonInsulating & reflects lightInsulating & reflects light

AsbestosAsbestosNatural fiberNatural fiberUsed in fire-resistant substancesUsed in fire-resistant substances

Rock WoolRock WoolMan-made mineral fiberMan-made mineral fiberUsed for insulation, seed pots, etcUsed for insulation, seed pots, etc

FiberglassFiberglassMan-made inorganic fiberMan-made inorganic fiberUsed for insulation, car bodies, Used for insulation, car bodies,

bathroom fixtures, etc bathroom fixtures, etc

Made from derivatives of petroleum, coal & Made from derivatives of petroleum, coal & natural gasnatural gasNylonNylon

Most durable of man-made fibersMost durable of man-made fibersExtremely lightweightExtremely lightweight

PolyesterPolyesterMost widely used man-made fiberMost widely used man-made fiber

AcrylicAcrylicLightweight, soft & resilient fiberLightweight, soft & resilient fiberProvides warmthProvides warmth

SpandexSpandexExtreme elastic propertiesExtreme elastic properties