Fibers Flashcards
(15 cards)
How to collect fibres (6)
taping
vaccuming
shake
comb
scraping
tweezering
How to tape:
s g
How to package a fibre
Paper envelope
Two types of fibres and their characteristics
Natural Fibre :
cellulose + protein
irregular pattern - scales, lumen
Synthetic fibre :
polymers and polyester
Smooth , uniform
manufacturer cord
Factors that affect the persistence of fibres (6)
no of contact
material
time spent
cleaning
position
activity
What are the three type of fibre effects (3)
Heat
Mechanical
Chemical
Heat effect (3)
Standing to close to the fire
Smoking cigarettes
Ironing
Mechanical effect 6
Tear - pulling apart
Cut - stab, slash, scissor
Puncture - push through
Abrasion- rubbing off
Animal - tear and cut
Microbial - bacterial fungi
Chemical effect 2
Corrosive liquids /acids
Bleach
How can you differentiae the different damage effects 5
angle of penetration
blade orientation
stabbing motion and force
blade sharpness
fabric elasticity
Primary transfer- evidential value 5
activity
time of contact
donor shedding potential
receipt material
area of contact
Secondary transfer- evidential value 4
Same as primary transfer
redistribution
activity since primary transfer
persistence of fibre type
Equipment for analysis of fibres 2
MSP- Micro-specto-photomery
Py-GC Pyrolysis Gas Chromatography
Micro-Spectro-photometry advantages and disadvantages
Advantages
- removes subjectivity
- quick and easy
-enables a fingerprint dye to be produced
- range of absorption
Disadvantages
- expensive
- specialist needs to analyse the results
- Specific samples ae required for preparation
Pyrolysis Gas Chromatography advantages and disadvantages
advantages
- fibre structure identified
- fits onto multiple analytical techniques
disadvantages
- destructive
- sample is easily contaminated
- easily breakable sample
- Expensive and requires a program to be learnt
