Advanced evidence type 1 - glitter

Question 1

What is glitter?

Answer 1

Synthetic multilayered particles - plastic (polyethylene, PBT/PMMA) or aluminium, or a hybrid.

these are cut from rolled sheets and tend to be hexagonal, rectangular or custom shaped.

Question 2

Where is glitter found?

Answer 2

decorative cosmetics
gel pens
fabrics, threads and yarns

Question 3

What is shimmer?

Answer 3

shimmer is predominantly mica based (muscovite)
when its used on its own, it exhibits a pearlescent effect

Question 4

what is the difference between shimmer and glitter?

Answer 4

Glitter is synthetic while mica based shimmer is natural

when mica is used alone, or coated with metal oxides, it never contains plastic. Glitter almost always does, unless it is aluminium based!

glitter will have identically shaped and sized particles while shimmer particles are irregularly shaped and sized

Question 5

What are the recovery considerations for glitter?

Answer 5

should be analysed similar to multilayered paint flakes
do not use JLar or acetate to maintain the integrity
Use a post it note itself
use a high intensity light source for optimum reflection
use a glass or plastic vial and then bagged
do not refrigerate or freeze - water may delaminate

Question 6

What is the analytical workflow for glitter?

Answer 6

Gross examination, recovery and collection
Preliminary evaluation of physical characteristics
Physical fit assessment - manufacturing defects can be as probative as physical fit assessments
All microscopic techniques - reflectance and transmission modes (x700 for morphology)
MSP - when analysing optically variable colours
(ATR) Infrared spectroscopy - plastic chemistry
place in a liquid of varying densities and it sits between the layers, this gives you the specific gravity measurement. Make sure to analyse the colour first!!!
Raman (micro) spectroscopy - polymer layers
SEM-EDX - microstructure detail and elemental composition of layers (aluminium) aluminium cannot be picked up with raman because it is silent in raman

Question 7

How is glitter interpreted?

Answer 7

look for:
- the number of particles and their physical dimensions
- location of particles on substrate because this provides you with context and aids in crime reconstruction.
- number, sequence, thickness and colour of layers (beware of subjectivity, this is when MSP is used)
-manufacturing defects - weathering, delamination can be highly discriminatory and provide a really high probative value

Question 8

How is glitter interpreted under a microscope?

Answer 8

oblique or alternate lighting as particles reflect differently. use colours black, grey or white backgrounds.
Q vs K comparisons must be performed side by side using the same background
ATR-FTIR for plastic chemistry on both sides

Question 9

How is glitter transferred?

Answer 9

Glitter is highly ubiqitous and persists really well - high retention value
however this poses as a problem due to the fact that we need to consider the background levels when looking at interpretation and context

Question 10

Why are the benefits of glitter serving as trace evidence?

Answer 10

they are seen as highly individualistic - e.g size, shape, specific gravity, morphology, number and thickness of layers, chemistry of layers (use BSE), cutting defects, vehicle etc
it is visible when it catches the light
it has a high probability of transfer and retention
it can be quickly collected, separated and concentrated - use of post it note
it ca be easily characterised as only one particle is required
it can be applied to chemo-metric due to its databasing capability and MVA
it is relatively persistent and resistant to degradation