Fibres

• basic unit of yarns and threads which then turn into fabrics, garments, textiles

• clothing • bedding • carpets • curtains • bandages • fibreglass • loft insulation • seatbelts

• can be plant, animal or mineral based • also known as staple fibres

• cotton • linen • hemp • coir • flax

• silk • wool • cashmere • camel • angora

asbestos

cellulose (polymer)

sericin/fibroin (polymeric protein)

due to prism-like structure

• naturally occuring silicate material • carcinogenic • sound absorbing, strong, cheap, fire resistant, electrical insulating

• also called filament fibres • longer than natural fibres • polymer with very high length to diamter ratio

• polyester • nylon • acrylic • polypropylene • glass fibre (made from silica which is natural but process of making it isnt)

• extruded through a spinneret device - polymer is pushed through tiny holes that are differently shaped • fibres spun into bundles called filaments • can alter the characteristics with different spinning techniques

• may become dislodged quickly after deposition • air dry wet clothing in controlled environment • store in paper bags to prevent mould growth • double package • submit whole item • druggists fold for small fibres • never package with debris from the scene

• gross examination, recovery and collection • preliminary evaluation of physical characteristics • physical fit assessment - most probative value • microscopic techniques • microspectrophotometry (UV-Vis) - colour determination • infrared spectroscopy - manufactured fibres • Raman spectroscopy - dyes and pigments

• thin layer chromatography • pyrolysis GS-MS • HPLC • melting point • microchemical tests ALL DESTRUCTIVE METHODS

• surface treatments • dye penetration • diameter and length • cross-section • chemical composition (type, polymer) • texture • colourant/dye - colour, type, how applied, weathering • natural or synthetic and type • striations (lines down the fibre) and pitting (holes/damage) • direction of yarn twist • threat count • coatings • scale protrusion on animal fibres

• colour - different dyes/pigments • chemical composition

• when the fibre is dyed during the manufacturing process - before, after being spun or after garment construction

• nature of contact • multiple association mitigate coincidental transfer • new fabrics possess loosley adhering fibres • old/damaged fabrics may shed more • tightly fibres shed less than staple fibres • background and persistence considerations

• cant state that it is unique • few databases for origin • often overlooked as difficult to locate • expensive, time-consuming skilled analysis

• stereoscopic • comparison • polarised • fluorescence • brightfield • thermal (destructive) • SEM and TEM • crystallography and diffraction

• surface treatments • dye penetration • diameter • chemical composition • cross section • texture • colourant/dye - colour, type, how applied, weathering

twisting shape