Composition, type , application and forensic investigation of paints.

1. PAINT AS A FORENSIC EVIDENCE
Presented by
Vaishnavi Borse
M.Sc. I yr.
Government Institute of Forensic Science

2. CONTENT
 Introduction
 Components of paint
 Types of paint
 Forensic analysis
 Case study
 Conclusion
 Reference

3. INTRODUCTION
 Paints are generally recognised as materials
applied to surface ranging from wood and paper to
a variety of metals, plastics and many composite
assemblies
 Paint as physical evidence
 Micro-traces of the paint
 Forensic investigation of paint evidence

4. COMPONENTS OF PAINTS
 There are some principle components of paints
1. Binder
2. Pigment
3. Solvent
 The binder providing the adhesion and cohesion,
keeping the pigment within the coating and
ensuring that the paint remains attached to the
substrate.
 Pigments provide colour and opacity.
 Solvents are present to aid manufacture and
application.

5. BINDER
 Provides binding effect
 Key ingredient that directly relates to a paints
performance, adhesion, wash ability, scrub
resistance, fade resistance or gloss retention.
 Alkyd (oil) based binders such as linseed oil, tung
oil, and soya oil.
 Modified oil binders = alkyd emulsion

6. PIGMENT
 Ground particles that are dispensed into paint and
provide color and hiding properties.
 There are two primary types of pigment - prime
pigments and extender pigments.
 Prime pigments:
• Wet and dry hide in paint.
• Titanium dioxide (TiO2)
• There are two main types - organic and inorganic.

7. PIGMENT
• Organic colorants
 Provide the brighter colors
 Examples .., Hansa yellow and phthalo blue.
 Not very durable
• Inorganic colorants
 Duller, earthy colors
 Examples ..,red oxide, yellow ochre and umber.
 More durable
o Extender pigments
• Lower cost pigments
• Contribute only to a paints dry hide
• Examples..., clay, silica, diatomaceous silica, calcium
carbonate, talc and zinc oxide.

8. SOLVENT
 Its is an liquid which carries the paint particles for
application and provides adhesion to the desired
surface.
 Combined with pigments and binders.

9. TYPES PAINTS
A. Household paints
• Protection and decoration
• two broad categories;
i. Orthodox Oil based paint: thinned by turpentine
ii. Emulsion paints: Vinyl or acrylic based thinned
with water.

10. B. Automotive paints
• Protection and decoration of automobiles
• Water-based acrylic polyurethane enamel paint
 Automotive paints come in liquid form, spray form,
and powder forms:-
1. Liquid: Usually polyurethane paints. Compressor
is needed to apply.
2. Spray: This is as same as perfume in spray bottle.
Made for DIYer.
3. Powder or additive: Paints in powder form applied
after mixing in paint thinner.

11. AUTOMOTIVE PAINT:
 Types of Automotive Paints
• Removable: These kinds of paints are made for
giving custom appearance to vehicle.
• Non-removable: Made for touch-ups and painting
vehicle.

12. FORENSIC ANALYSIS:
 To find its source of origin by comparing the
questioned sample with the standard.
 The good amount sample should be available for
result.
 Collecting tools such as sharp edge knife for
scraping, white paper funnels for the chip collection,
sealing of paint chip in container etc.

13. MICROSCOPIC TECHNIQUE:-
 The stereomicroscope is used to determine the
number, sequence, colour, thickness and texture of
each layer in paint.
 Polarized Light Microscope is used to study the
optical properties of transparent sample such as
pigments using the transmitted polarized light
 Fluorescence microscope is used to observe the
visible fluorescence of opaque and transparent
samples.
 Scanning Electron Microscopy-Energy Dispersive
X-ray Analysis is used for the qualitative analysis of
the elements present in the pigments.

14. SPECTROSCOPIC TECHNIQUES:-
 Fourier Transform Infrared Spectroscopy.
 Both organic and inorganic components can be
detected using the IR spectroscopy.
 The XRF is also very useful for the elemental
analysis of lead in paint.
 Raman spectroscopy can also be used for the
identification of binders, pigments, additive and
coatings

15. MICRO-CHEMICAL TEST
 Also known as , solvent test.
 Based on reactions of pigments and binder with the
oxidizing and reducing agents.
 Reactions such as layer dissolution, swelling,
softening, filler effervescence, and flocculation and
colour changes are noted.

16. PYROLYSIS GAS CHROMATOGRAPHY-MASS
SPECTROSCOPY
“Destructive technique that uses the pyrolytic
breakdown of products to differentiate the types of
binders and plasticizers in paints.”
 Determination of approximate age of paints.
 Presence or absence of monomers helps in
distinguishing.

17. CASE STUDY:
One hit and run accident case was reported in
district Jind. In this case one motorcycle was found in
badly damaged conditions at the scene of accident. In
this incident the person riding on the motorcycle was
died. The motorcycle was observed to be having red
transfer of paint on its damaged and detached battery
cover which was collected for comparison with the
accused vehicle. A number of vehicles were rounded
up later on which were suspected to be involved in
the collision.

19. CONCLUSION
 Trace evidence.
 Primary components as well as secondary
components which may vary as per the type of
paints.
 There are different techniques to analyzed paint but
it is advisable to first apply non-destructive
techniques for the examination.

20. REFERENCE
 Mr. Krunal N. Jariwala, “Forensic Examination of paints”
,Indian journal ofapplied research,Volume 4, Issue 7, July
2014
https://www.worldwidejournals.com/indian-journal-of-applied-
research(IJAR)/recent_issues_pdf/2014/July/July_2014_140566
1208__75.pdf
 Mr. Ajay Kumar, “Exchange of Paint in Hit & Run Collisions
and Its Significance as Forensic Evidence”, Journal of forensic
science and investigation, Volume 8,Issue 1, March 2018.
https://juniperpublishers.com/jfsci/pdf/JFSCI.MS.ID.555728.pdf
 Federal bureau of investigation(FBI), “Forensic paint analysis
and guidelines”, Forensic science commmuncation,Volume1,
Issue 2, July 1999
https://www.fbi.gov/about-us/lab/forensic-science
communications/fsc/july1999/painta.htm

21. THANK YOU !!!