Lecture 18 - Glitter

Question 1

what is glitter made of

Answer 1

synthetic multi-layered particles of plastic, aluminium foils or a bit of both

plastics = polyethylene, PBT, PMMA

Question 2

how is glitter normally made

Answer 2

being cut from rolled sheets and can be a variety of shapes

Question 3

where is glitter often found

Answer 3

decorative cosmetics
sun creams
skin care or personal care products
gels pens
temp tattoos
glue
paint
loose
on glass
in fabrics or yarns

Question 4

how does shimmer differ from glitter

Answer 4

shimmer is:

normally mica based (natural)

doesn’t contain plastic

has its own pearlescent effects

can be used as a substrate and coated with other metal oxides to give interference effects

particles are often irregular shapes and sizes

glitter is:

synthetic

almost always contains plastic or is aluminium based

more uniform shapes and sizes of one type

Question 5

what should glitter and shimmer traces be analysed like

Answer 5

multi-layered paint flakes

use high intensity light sources as glitter is likely to reflect light

Question 6

how should glitter evidence be recovered

Answer 6

not using J-Lar or acetate tape as this can destroy the layers

put into a glass or plastic vial and then evidence bag

Question 7

should you put glitter evidence in the fride/freezer

Answer 7

no, is moisture gets in it can tear apart layers

Question 8

what is the analytical workflow for glitter evidence

Answer 8

1. gross examination, recovery and collection
2. prelim evaluation of physical characteristics
3. microscopic techniques - refelctance and tranmission modes
4. MSP
5. ATR IR spectroscopy - for plastic chemistry
6. specific gravity test
7. Raman micro spectroscopy
8. SEM-EDX

physical fit does not apply here

Question 9

why can aluminium stubs be used to hold glitter sample in raman spectroscopy despite glitter being made of aluminium

Answer 9

aluminium doesn’t have a raman active mode so wont be picked up as a signal in raman

Question 10

what is the specific gravity test

Answer 10

put glitter sample in two solids of different densities and see where the glitter residues

but be careful as this could strip- the colour do colour determination test first

Question 11

why does the colour of glitter need to be carefully considered

Answer 11

the colour of glitter can be optically variable depending on the light source, angle and surrounding objects

Question 12

what could be key in glitter morphologies when making comparisons between samples

Answer 12

the presence of manufacturing defects

Question 13

what are things to look for when interpreting glitter evidence

Answer 13

number of particles and their physical dimensions

particle location

number, sequence, thickness and colour of layers

manufacturing defects, weathering, delamination, corrosion, damage

Question 14

what part of the interpretation of glitter evidence introduces the most subjectivity and how if this reduced

Answer 14

colour

using MSP

Question 15

when observing glitter using light microscopy what three things is it essential to do and why

Answer 15

alternate the lighting source and angle - particles reflect light differently depending on the type and angle

use different backgrounds e.g black, grey and white to help with colour determination

look at both sides of the glitter as these might not be the same

Question 16

what must questioned and known comparisons be done using

Answer 16

side by side comparisons with the same instrument settings and background colour

Question 17

what technique is used to look at the plastic chemistry of glitter

Answer 17

ATR-FTIR

Question 18

why does glitter tend to be very persistent

Answer 18

glitter is small, lightweight and plastic takes a long time to degrade

sticks well but not on shiny surfaces

Question 18

what reduced the likleyhood of a coincidental transfer of trace evidence

Answer 18

multiple associations

Question 19

why is the use of glitter not often heard of in crime investigations

Answer 19

can be expensive (method used)

time consuming

is often overlooked

requires more skills than other types of evidence

Question 20

why is the use of glitter a goof type of trace evidence to consider

Answer 20

they are highly individualistic - size, shape, thickness, colour - layers!

almost invisible - likely to be missed when criminals clean up

high transfer and persistence

resistance to degradation

can be quickly separated and collected from scenes

can be used with chemometrics

Question 21

what is an issue that has recently arisen with using glitter as evidence

Answer 21

the ban of plastic use in glitter manufacture - people may use cellulose or glass instead

but just because it is band doesn’t mean it will never be encountered in case work