Fiber Transfer ActivityFiber Transfer Activity

Rub your sleeve against your Rub your sleeve against your neighbor’s sleeve. Then answer the neighbor’s sleeve. Then answer the following questions:following questions:

Can fibers from one sleeve be Can fibers from one sleeve be detected on the other?detected on the other?

Do hand lenses or masking tape aid Do hand lenses or masking tape aid the investigation? How?the investigation? How?

Fiber AnalysisFiber Analysis

Introduction to FibersIntroduction to Fibers

Trace evidenceTrace evidence Class evidenceClass evidence Direct transferDirect transfer: suspect : suspect victim victim Secondary transferSecondary transfer: source : source

suspect suspect victim victim 95% of fibers lost from crime scene 95% of fibers lost from crime scene

within 24 hourswithin 24 hours

Forensic scientist Forensic scientist determines:determines:

Type of fiberType of fiber ColorColor How many of each kindHow many of each kind Textile originTextile origin Multiple FibersMultiple Fibers TransfersTransfers Type of crimeType of crime

Fiber EvidenceFiber EvidenceCollected by:Collected by: Special vacuums (large areas)Special vacuums (large areas) Sticky tapeSticky tape ForcepsForceps

Tested by:Tested by: Microscopy – polarizing light, infraredMicroscopy – polarizing light, infrared Burn test (large quantities only)Burn test (large quantities only)

Fibers are spun into Fibers are spun into yarnsyarns that have that have specific characteristicsspecific characteristics

Yarns are woven, with different Yarns are woven, with different patterns, into patterns, into textilestextiles

Fibers may be Fibers may be naturalnatural or or syntheticsynthetic

Fiber ClassificationFiber Classification(Use textbook p. 81-84)(Use textbook p. 81-84)

Natural Fibers:Natural Fibers:

(List the different (List the different types and types and examples of each)examples of each)

Synthetic Fibers:Synthetic Fibers:

(List the different (List the different types and types and examples of each)examples of each)

Natural FibersNatural Fibers Animal fibers Animal fibers (protein)(protein)

Sheep – woolSheep – wool Goats – cashmere, mohairGoats – cashmere, mohair Rabbits – angoraRabbits – angora Caterpillar – silkCaterpillar – silk

Plant fibers Plant fibers (cellulose)(cellulose) Seed: cottonSeed: cotton Fruit: coir (coconut)Fruit: coir (coconut) Stem: hemp (Stem: hemp (CannabisCannabis), jute, flax (linen)), jute, flax (linen) Leaf: manila, sisalLeaf: manila, sisal

Mineral fibersMineral fibers Fiberglass (glass) , asbestosFiberglass (glass) , asbestos (rock mineral) (rock mineral)

WOOL

COTTON

FIBERGLASS

ASBESTOS

FLAX

JUTE

HEMP

SILK

Synthetic (Man-made) Synthetic (Man-made) FibersFibers

Regenerated fibers (modified natural Regenerated fibers (modified natural fibers)fibers) RayonRayon CelaneseCelanese CapronCapron

Synthetic polymer fibersSynthetic polymer fibers PolyesterPolyester NylonNylon AcrylicAcrylic OlefinsOlefins