L7: HAIR, FIBRES, GLASS AND PAINT EVIDENCE

Question 1

hair is mainly comprised of?

Answer 1

keratin

Question 2

how much does hair grow per month?

Answer 2

1cm

Question 3

Hair fibres grow in what pattern?

Answer 3

cyclic growth pattern

Question 4

whats 1000 days of growth and whats 100 days fo rest?

Answer 4

1000 - anagen

100 - telegen

Question 5

whats the intermediate period in hair called?

Answer 5

catagen

Question 6

what percent is anagen?

Answer 6

80-90% anagen

Question 7

what percent tis telegen?

Answer 7

10-18% telegen

Question 8

what are naturally shed hairs ?

Answer 8

mainly telegen undamaged hair root

Question 9

anagen has a _____ root.

Answer 9

damaged

Question 10

outer shaft of hair is ___

Answer 10

cuticle

Question 11

main body of hair ____

Answer 11

cortex

Question 12

core of the fibre is ____

Answer 12

medulla

Question 13

hair diameter is between?

Answer 13

approximately 40 - 100 mm

Question 14

what are the key characteristics of hair?

Answer 14

Length, shape, size,

colour, stiffness, curliness

Question 15

European hair is known as?

Answer 15

caucasoid

Question 16

features of caucasoid hair are?

Answer 16

• Fine to medium coarseness
• Straight or wavy
• Oval to circular hair shaft
• Even pigmentation (medium – fine)

Question 17

Asian hair is known as

Answer 17

Mongoloid

Question 18

features of Mongoloid hair?

Answer 18

• Coarse and straight with large diameter
• Circular cross-section
• Large pigment granules; reddish

Question 19

African hair is known as?

Answer 19

negroid

Question 20

features of negroid hair?

Answer 20

Kinks and curls, flattened cross- section
Largest pigmentation granules
Opaque fibre

Question 21

do hairs have a lot of individualising features?

Answer 21

no

Question 22

do FBI to hair analyses?

Answer 22

no

Question 23

what difficult with hair analysis ?

Answer 23

• Variation between hairs from the same source
• Quality (length of hair)
• Time difference
• Experience of forensic examiner

Question 24

There are ___ natural and synthetic fibres

Answer 24

countless

Question 25

fibres secondary transfer is ____

Answer 25

fast

Question 26

where are fibres strong?

Answer 26

along the length

Question 27

fibres have low?

Answer 27

solubility and elasticity

Question 28

do fibres have a high or low melting point?

Answer 28

high melting point

Question 29

How long are animal fibres?

Answer 29

10 – 80 microns

Question 30

what are natural fibres?

Answer 30

Animal fibres Veg fibres Mineral fibres

Question 31

what are natural animal fibres?

Answer 31

silk wool hair

Question 32

what are natural veg fibres?

Answer 32

``` linen cotton jute kapok coir ```

Question 33

what are mineral fibres?

Answer 33

asbestos

Question 34

what are synthetic fibres?

Answer 34

organic fibres and inorganic fibres

Question 35

name organic fibres that are synthetic polymers?

Answer 35

polyethene, polyvinyl derivatives, polyurethane, polyamide, polyester

Question 36

name organic fibres the are natural polymers?

Answer 36

cellulose, materials, rayon, viscose, modal, rubber

Question 37

Name inorganic fibres

Answer 37

carbon, ceramic, glass, metal,

Question 38

what do cotton fibres look like?

Answer 38

irregular “U-shaped” appearance in cross-section a twisted undulating and irregular appearance along their length

Question 39

what does wool look like?

Answer 39

More cylindrical appearance with circular/ oval cross-section Scalar features along the length of the fibre (hair-like)

Question 40

what do synthetic fibres viscose or triacetate look like?

Answer 40

Appearance of both examples due to manufacture process Indentations along the length give the fabric an appropriate quality appearance.

Question 41

whats a good thing about fibre evidence?

Answer 41

strongly classifiable and often individualisation may be possible.

Question 42

How to find out what type of polymer a fibre is?

Answer 42

``` Refractive index and birefringence or infrared microscope or raman micro-spectrometry ```

Question 43

How to find out the colour of a fibre?

Answer 43

UV-Visible microspectrophotometry

Question 44

How to find out a dye mix ?

Answer 44

Chromatography

Question 45

which technique for fibre analysis is destructive?

Answer 45

chromatography

Question 46

what is glass comprised of?

Answer 46

Silica with sodium carbonate

Question 47

what additives improve the durability of glass?

Answer 47

limestone | alumino-silicate

Question 48

natural glass has what colour tint and why?

Answer 48

green because of Fe2O3 from sand

Question 49

Glass is very ___ and can be _____

Answer 49

classifiable | individualised

Question 50

what forensic analyses for glass can be done?

Answer 50

• Physical matching of fragments • Flatness/ curvature, optical properties and fracture surfaces • Density of glass • Refractive index (RI) of fragments • Elemental analysis of trace elements (metals)

Question 51

how is paint usually evidence?

Answer 51

chips or scrapings

Question 52

what is paint made from?

Answer 52

binder pigment solvent

Question 53

what does binder do in paint?

Answer 53

helps paint adhere is surface

Question 54

what does pigment do in paint?

Answer 54

provides colour and opacity

Question 55

what does solvent do in paint?

Answer 55

gives liquid properties, dries during use

Question 56

how thick is paint layer usually?

Answer 56

20mm – 50mm upwards

Question 57

white and black paint are usually ______

Answer 57

inorganic

Question 58

pigments are generally ?

Answer 58

insoluble

Question 59

binders are based on?

Answer 59

oils, gums or resins

Question 60

forensic analysis of paint involves

Answer 60

Physical matching of fragments

Question 61

How else can paint be analysed?

Answer 61

Microscopic examination and measurement of layer thickness and appearance

Question 62

How to find the chemical composition of paint ?

Answer 62

FTIR or Raman spectroscopy

Question 63

How to find the colour of paint?

Answer 63

UV-Vis spectroscopy

Question 64

How to find elemental composition of paint?

Answer 64

X-ray analysis

Question 65

How can crystalline pigments be analysed?

Answer 65

X-ray powder diffraction