Lecture 13&14 - Makeup Flashcards
what cosmetic products that used to be used were found toxic and what were they replaced with
lead and mercury
replaced with Titanium and Zinc oxides
what are the 7 main categories of cosmetics
decorative cosmetics
hair care
perfume
body care
sun care
oral care
skin care
how can cosmetic evidence be characteristic of a person
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
what is a cosmetic defined as
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
name a product that is
a) a drug but not a cosmetic
b) both a cosmetic and a drug
a) anti dandruff shampoo
d) toothpaste with fluoride
what products come under decorative cosmetics
nail varnish
foundation
blusher
lipstick
mascara
eyeshadow
what can make categorising cosmetics difficult
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
what makes decorative cosmetics good trace evidence (5)
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
what could decorative cosmetics be used to cover up
blemishes, tattoos, hyperpigmentation, scars
in the hierarchy of evidence, what level proposition can cosmetic traces give
activity level propositions
- so can be used to reconstruct an event
what results in an increase in probative value of cosmetic evidence (3)
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
are pigments or dyes more used in cosmetics
pigments
what type of pigments are used in facial cosmetics
inorganic (mineral) pigments
what type of Titanium dioxide is used for maximum opacity
pigment grade TiO2 particles = 0.25 micrometre
what type of pigments are used in lipsticks
organic (lakes) pigments
what does the particle size of a pigment determine
its properties
what type of Titanium dioxide is used for sun creams
nano TiO2 particles = less than 0.1 micrometre
what are non hiding white pigments used for in cosmetics and give some examples
used as extenders
e.g calcium carbonate
talc
china clay (kaolin)
silica
what are the most important inorganic pigments in cosmetics
titanium dioxide
iron oxide (red, yellow, black)
bismuth oxychloride
mica
zinc oxide
ultramarine -
(blue/purple/pink)
what are the most important metallic elements of cosmetics
aluminium flakes
iron oxide/TiO2 coated mica flakes
what does pearlescent mean
a subtle colour and bright white reflection giving a pearl-like appearance
what does interference/iridescent mean
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
what is goniochromism
an effect where surfaces appear to change
what determines the colour seen by iridescent and pearlescent substances
the thickness and composition of the layers that make them up
how are the majority of iridescent material made
synthetically
what are interference/iridescent pigments more commonly known as
shimmer
what is shimmer very different to
glitter
what are interference pigments made up of
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
what is mica and what can it be divided into
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
what is a pearlescent pigment that becomes an interference pigment when coated on mic
BiOCl = bismtuh oxychloride
what determines the colour seen of an interference pigment
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
what is a problem with using mica as the base substrate for interference pigments
mica is a finite resource so alternative sources will be needed
what are alternative substrates to mica (3) and why are these good (3)
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
what mode of SEM is better for looking at density
backspatter
what do cosmetic traces have that fibres don’t
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
what does a larger pigment particle size lead to in interference pigments
a brighter more metallic finish
what four recovery consideration of cosmetic evidence is also used in fibre evidence
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)
how should cosmetic evidence be stored
at room temperature if possible but can be refrigerated if there is suspected DNA traces also
why are moistened swabs not good for cosmetic trace evidence collected
they can hydrate the sample and possibly chemically alter it
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 physical fit assessment
cosmetic traces tend to be liquid transfers
what is the general analytical workflow for cosmetic trace evidence
- gross examination, recovery, collection
- preliminary evaluation of physical characteristics
- microscopic techniques
- MSP - microspectrophotometry
- IR spectroscopy
- Raman spectroscopy
- SEM-EDX
- XRF
- XRD
- GC-MS and other chemical tests
what is MSP used for
colour determination
what is IR spectroscopy used for
organic content and silicones
what is raman spectroscopy used for
inorganic pigments
what is SEM-EDX used for
SE (secondary electron) mode for surface analysis and BSE (backspatter) mode for sample homogeneity
what is XRF used for
elemental composition
what is XRD used for
crystal structure and polymorphs
what must we document of a suspected cosmetic transfer
the location on the substrates and the colour using visual analysis and then microscopic techniques for further examination
what microscopic technique is particularly good for cosmetic analysis
fluorescence microscopy
what must known and questioned samples be compared using
side by side comparisons with the same background colour
also the same lighting angle and type
what type of light is good for observing pigment distribution
transmitted light through the samples
what type of light is good for observing layers or texture of a sample
reflected light from the sample
what theory underlies the colour classification of cosmetic pigments - what three things make up this model
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
in microscopy, what background colours should be used to help with colour determination
black, grey and white q
what is the chroma of a fluorescent pigment
30
how can the presence of interference/iridescent pigments be identified in microscopic analysis
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
what is another colour chart that could be useful particularly for facial cosmetics and why
Munsell soil chart
iron oxide is a pigments found in facial cosmetics and it comes from dirt
how can you tell apart natural and synthetic mica
using SEM-EDX
natural has fluorine in it
natural also has uneven edges whereas synthetic is likely to have smoother edges
what are some things to note when observing cosmetics under a microscope and making comparisons
colour
pigment distribution
particle morphology
surface features (edges)
component encapsulation
presence of mica or borosilicate glass
how can you tell between borosilicate glass and mica substrates
borosilicate glass will be more translucent, have sharper edges and a uniform thickness
what is something that companies will not often share that can impact identifying a cosmetic product
the exact product formulation
does a forensic cosmetic database exist
no, there is a mineral one (RRUFF)
why is raman chosen over FTIR is cosmetic analysis
raman can look at lower wavelengths with high accuracy and this is the region where information is relevant
(below 500 cm-1)
