Lecture 18 - Glitter Flashcards
what is glitter made of
synthetic multi-layered particles of plastic, aluminium foils or a bit of both
plastics = polyethylene, PBT, PMMA
how is glitter normally made
being cut from rolled sheets and can be a variety of shapes
where is glitter often found
decorative cosmetics
sun creams
skin care or personal care products
gels pens
temp tattoos
glue
paint
loose
on glass
in fabrics or yarns
how does shimmer differ from glitter
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
what should glitter and shimmer traces be analysed like
multi-layered paint flakes
use high intensity light sources as glitter is likely to reflect light
how should glitter evidence be recovered
not using J-Lar or acetate tape as this can destroy the layers
put into a glass or plastic vial and then evidence bag
should you put glitter evidence in the fride/freezer
no, is moisture gets in it can tear apart layers
what is the analytical workflow for glitter evidence
- gross examination, recovery and collection
- prelim evaluation of physical characteristics
- microscopic techniques - refelctance and tranmission modes
- MSP
- ATR IR spectroscopy - for plastic chemistry
- specific gravity test
- Raman micro spectroscopy
- SEM-EDX
physical fit does not apply here
why can aluminium stubs be used to hold glitter sample in raman spectroscopy despite glitter being made of aluminium
aluminium doesn’t have a raman active mode so wont be picked up as a signal in raman
what is the specific gravity test
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
why does the colour of glitter need to be carefully considered
the colour of glitter can be optically variable depending on the light source, angle and surrounding objects
what could be key in glitter morphologies when making comparisons between samples
the presence of manufacturing defects
what are things to look for when interpreting glitter evidence
number of particles and their physical dimensions
particle location
number, sequence, thickness and colour of layers
manufacturing defects, weathering, delamination, corrosion, damage
what part of the interpretation of glitter evidence introduces the most subjectivity and how if this reduced
colour
using MSP
when observing glitter using light microscopy what three things is it essential to do and why
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
