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Trace Evidence > Lecture 13&14 - Makeup > Flashcards

Lecture 13&14 - Makeup Flashcards

1
Q

what cosmetic products that used to be used were found toxic and what were they replaced with

A

lead and mercury

replaced with Titanium and Zinc oxides

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2
Q

what are the 7 main categories of cosmetics

A

decorative cosmetics
hair care
perfume
body care
sun care
oral care
skin care

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3
Q

how can cosmetic evidence be characteristic of a person

A

everyone uses different products and if make up shades/colours of products

the order of these products will be different for every one

the application method also has an affect

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4
Q

what is a cosmetic defined as

A

any substance or mixture intended to be placed in contact with various external parts of the human body…with a view exclusively or mainly to cleaning them, perfuming them, changing their appearance and/or correcting body odours and/or protecting them or keeping them in good condition

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5
Q

name a product that is
a) a drug but not a cosmetic
b) both a cosmetic and a drug

A

a) anti dandruff shampoo
d) toothpaste with fluoride

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6
Q

what products come under decorative cosmetics

A

nail varnish
foundation
blusher
lipstick
mascara
eyeshadow

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7
Q

what can make categorising cosmetics difficult

A

they can have more than one use e.g bronzer can also be used as eyeshadow

  • just because they have an intended purpose doesn’t mean they are used for this purpose always
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8
Q

what makes decorative cosmetics good trace evidence (5)

A

easily transferred upon contact (two way transfers)

relatively persistent - can be hard to wash out

independent of age, gender, ethnicity

generally cover a large surface area

give investigative leads

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9
Q

what could decorative cosmetics be used to cover up

A

blemishes, tattoos, hyperpigmentation, scars

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10
Q

in the hierarchy of evidence, what level proposition can cosmetic traces give

A

activity level propositions

  • so can be used to reconstruct an event
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11
Q

what results in an increase in probative value of cosmetic evidence (3)

A

the use of uncommon cosmetics or layering different combination of cosmetics

also the mixture of cosmetic with different peoples skin

the application method used - brush or sponge

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12
Q

are pigments or dyes more used in cosmetics

A

pigments

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13
Q

what type of pigments are used in facial cosmetics

A

inorganic (mineral) pigments

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13
Q

what type of Titanium dioxide is used for maximum opacity

A

pigment grade TiO2 particles = 0.25 micrometre

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13
Q

what type of pigments are used in lipsticks

A

organic (lakes) pigments

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13
Q

what does the particle size of a pigment determine

A

its properties

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13
Q

what type of Titanium dioxide is used for sun creams

A

nano TiO2 particles = less than 0.1 micrometre

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14
Q

what are non hiding white pigments used for in cosmetics and give some examples

A

used as extenders

e.g calcium carbonate
talc
china clay (kaolin)
silica

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15
Q

what are the most important inorganic pigments in cosmetics

A

titanium dioxide
iron oxide (red, yellow, black)
bismuth oxychloride
mica
zinc oxide
ultramarine -
(blue/purple/pink)

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16
Q

what are the most important metallic elements of cosmetics

A

aluminium flakes
iron oxide/TiO2 coated mica flakes

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17
Q

what does pearlescent mean

A

a subtle colour and bright white reflection giving a pearl-like appearance

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18
Q

what does interference/iridescent mean

A

light reflection and refraction with the colour changing relative to the angle of observation and illumination = rainbow-like appearance

e.g oil spill on water, CD surface, fish scales

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19
Q

what is goniochromism

A

an effect where surfaces appear to change

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20
Q

what determines the colour seen by iridescent and pearlescent substances

A

the thickness and composition of the layers that make them up

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21
Q

how are the majority of iridescent material made

A

synthetically

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22
Q

what are interference/iridescent pigments more commonly known as

A

shimmer

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23
Q

what is shimmer very different to

A

glitter

24
Q

what are interference pigments made up of

A

layers of metal oxides on a mica substrates - tend to be 500nm thick

e.g of metal oxides include
titanium dioxide
iron (II) oxide
iron (III) oxide
bismuth oxychloride
SnO2
carmine
chromium oxide
ferric ferrocyanide

25
Q

what is mica and what can it be divided into

A

a naturally occurring silicate mineral (rock)

can be divided into layers or flakes which can be translucent these layers can become coated in metal oxides resulting in different colours being observed

26
Q

what is a pearlescent pigment that becomes an interference pigment when coated on mic

A

BiOCl = bismtuh oxychloride

27
Q

what determines the colour seen of an interference pigment

A

the thickness and type of metal oxide that coats the mica substrate

the number and order of metal oxide layers too - a mixture of metal oxides can coat the mica

these things affect the colours reflected and absorbed

28
Q

what is a problem with using mica as the base substrate for interference pigments

A

mica is a finite resource so alternative sources will be needed

29
Q

what are alternative substrates to mica (3) and why are these good (3)

A

borosilicate glass
silica
alumina

due to being synthetic these material can be made thinner and more uniform than natural mica

they are colourless themselves (mica is slightly yellow)

they have a lower RI (refractive index) than mica so increase the interference intensity

30
Q

what mode of SEM is better for looking at density

A

backspatter

31
Q

what do cosmetic traces have that fibres don’t

A

better adhesive properties - likely to remain on clothing, bedding and other material like this

this is due to cosmetics mixing with the oils in skin and being more naturally sticky compared to fibred

32
Q

what does a larger pigment particle size lead to in interference pigments

A

a brighter more metallic finish

33
Q

what four recovery consideration of cosmetic evidence is also used in fibre evidence

A

if garments are wet air dry in a controlled environment first

store evidence in paper bags to prevent mould growth

never package along with other debris from the scene

if you can recover whole item then do it (control samples needed as close to samples as possible)

34
Q

how should cosmetic evidence be stored

A

at room temperature if possible but can be refrigerated if there is suspected DNA traces also

35
Q

why are moistened swabs not good for cosmetic trace evidence collected

A

they can hydrate the sample and possibly chemically alter it

35
Q

despite having the more probative value in other types of trace evidence, what step in the analytical workflow is not common in cosmetic evidence and why

A

a physical fit assessment

cosmetic traces tend to be liquid transfers

36
Q

what is the general analytical workflow for cosmetic trace evidence

A
  1. gross examination, recovery, collection
  2. preliminary evaluation of physical characteristics
  3. microscopic techniques
  4. MSP - microspectrophotometry
  5. IR spectroscopy
  6. Raman spectroscopy
  7. SEM-EDX
  8. XRF
  9. XRD
  10. GC-MS and other chemical tests
37
Q

what is MSP used for

A

colour determination

38
Q

what is IR spectroscopy used for

A

organic content and silicones

39
Q

what is raman spectroscopy used for

A

inorganic pigments

40
Q

what is SEM-EDX used for

A

SE (secondary electron) mode for surface analysis and BSE (backspatter) mode for sample homogeneity

41
Q

what is XRF used for

A

elemental composition

42
Q

what is XRD used for

A

crystal structure and polymorphs

43
Q

what must we document of a suspected cosmetic transfer

A

the location on the substrates and the colour using visual analysis and then microscopic techniques for further examination

44
Q

what microscopic technique is particularly good for cosmetic analysis

A

fluorescence microscopy

45
Q

what must known and questioned samples be compared using

A

side by side comparisons with the same background colour
also the same lighting angle and type

46
Q

what type of light is good for observing pigment distribution

A

transmitted light through the samples

47
Q

what type of light is good for observing layers or texture of a sample

A

reflected light from the sample

47
Q

what theory underlies the colour classification of cosmetic pigments - what three things make up this model

A

Munsell’s colour theory - this is a 3D model

based on the hue, value (brightness) and chroma (saturation)

value 0 = black and 10 = white
chroma 0 = neutral and there is no end value (approx 30)
hue = five main colours (red, yellow, green, blue, purple) and the 5 in between each

47
Q

in microscopy, what background colours should be used to help with colour determination

A

black, grey and white q

47
Q

what is the chroma of a fluorescent pigment

A

30

47
Q

how can the presence of interference/iridescent pigments be identified in microscopic analysis

A

by changing the angle of the light hitting the sample or the position of the sample relative to the light to see if different colours are observed

if different colours are seen when the angle of light is changed this suggests the presence of interference pigments

47
Q

what is another colour chart that could be useful particularly for facial cosmetics and why

A

Munsell soil chart

iron oxide is a pigments found in facial cosmetics and it comes from dirt

48
Q

how can you tell apart natural and synthetic mica

A

using SEM-EDX

natural has fluorine in it
natural also has uneven edges whereas synthetic is likely to have smoother edges

49
Q

what are some things to note when observing cosmetics under a microscope and making comparisons

A

colour
pigment distribution
particle morphology
surface features (edges)
component encapsulation
presence of mica or borosilicate glass

50
Q

how can you tell between borosilicate glass and mica substrates

A

borosilicate glass will be more translucent, have sharper edges and a uniform thickness

51
Q

what is something that companies will not often share that can impact identifying a cosmetic product

A

the exact product formulation

52
Q

does a forensic cosmetic database exist

A

no, there is a mineral one (RRUFF)

53
Q

why is raman chosen over FTIR is cosmetic analysis

A

raman can look at lower wavelengths with high accuracy and this is the region where information is relevant
(below 500 cm-1)

54
Q
A
55
Q
A

Trace Evidence (18 decks)

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