Glitter

• Not the same as shimmer • Synthetic multilayered particles - plastic or aluminium, or a hybrid • Cut from rolled sheets, tend to be hexagonal, square or rectangle, or a custom shape

• Decorative cosmetics • Sunscreens • Gel pens • Temporary tattoos • Glue • Paints • Woven in fabric

• Mainly mica based • Used on its own (pearlescent effects) • Used as a substrate then coated with various metal oxides

• Middle layer of mica (low refractive index) • Surrounded by metal oxide layer that has a high rerfractive index • Can be multilayered to give more discriminatory value • Thickness of metal oxide layers dictate colours reflected and transmitted

• Borosilicate glass, silica, alumina • Thinner and more uniform than natural mica • Colourless (mica is slightly yellow) • Lower RI than mica - increases interference

• Glitter is synthetic, mica based shimmer is natural • Mica alone or coated with metal oxides never contains plastic, glitter almost always does (or is aluminium based) • Glitter will have identically shaped and sized particles, shimmer particles are irregular and randomly shaped and sized

• Should be analysed as multilayered paint flakes • Use a high intensity light source • Must not be lifted with J-Lar or acetate • Glass or plastic vial is best then a bag • Embedded particles must not be removed at scene • Dont refrigerate or freeze

• gross examination, recovery, collection • preliminary evaluation of physical characteristics (microscopy of gauge) • physical fit - manufacturing defects • all microscopic techniques • microspectrophotometry • ATR infrared spectroscopy (plastic chemsitry) • specific gravity • raman micro spectroscopy (polymer layers) • SEM-EDX - elemental composition of layers

• Number of particles and their physical dimensions • Location of particles • Number, sequence, thickness and colour of layers • Manufacturing defects, weathering, delamination, corrosion, damage

• Probative value • Has the potential to match to a particular machine and so the manufactuer

• Oblique or alternate lighting as particles reflect differently • Alternate between black, grey, and white backgrounds to facilitate colour determinations

• highly individualistic - different shape, thickness, size, number, morphology • nearly invisible • high probability of transfer and retention • quickly collected, separated and concentrated • easily characterised • databsing capabilities • relatively persistent and resistant to degradation