fiber transfer activity. rub your sleeve against your neighbor’s sleeve. then answer the following...
TRANSCRIPT
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?
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)