Forensic Paint Analysis
Course
Forensic Science
Unit VII
Paint
Essential
Question
How can paint
chips be
observed,
compared, and
used to prove
ownership?
TEKS
§130.295(c)
(1)(A)(B)
(2)(F)(G)(H)
(3)(A)(D)(E)(F)
(5)(C)(E–J)
(6)(A–D)(G)(H)
(7)(A)
Prior Student
Learning
 Compounds/
elements
 Solutes and
solvents
 How paint is
considered a
basic
compound
Estimated Time
4 hours total
 45 min. lecture
 45 min. Paint
Activity Day 1
 30 min. Paint
Activity Day 2
 30 min. Review
Puzzle
 30 min. Quiz
Rationale
A black car is not always “just a black car.” When black paint from several
different vehicles is compared, it can sometimes look as though they are all
the same. If a person wanted to cover a small scratch or ding, any black paint
might do. However, when the situation is more serious, such as a hit-and-run,
forensic science can be used to analyze the paint and tell different shades of
black from each other to solve crimes.
Objectives
The student will be able to:
1. Identify the different components of automobile paint.
2. Characterize the microscopic examination of paint.
3. List and define the techniques used in paint comparisons.
4. Understand how to properly collect and preserve paint evidence.
Engage
Use the following story and questions for a class discussion. Use the
Discussion Rubric for assessment.
http://en.wikipedia.org/wiki/Murder_of_Vicky_Lynn_Hoskinson
 How was the bicycle (pink paint) a key piece of evidence in this case?
 Could it have been any pink bike?
 What other factors linked investigators to the suspect?
Key Points
I. Comparison of Paint
A. Paint is composed of a binder and pigments, and other additives that
are dissolved or dispersed in a solvent
B. Auto paint is the most common type of paint examined in crime labs
C. Layers of automobile paint
1. Electrocoat primer – applied to the steel body of a car for
corrosion resistance; colors range from black to grey
2. Primer surfacer – applied to the primer to completely smooth it
out and hide any seams or imperfections; highly pigmented (light
grey for lighter colored cars and red oxide under dark colors)
3. Basecoat – the actual color of a vehicle
4. Clearcoat – unpigmented; improves gloss, durability, and
appearance
II. Microscopic Examination of Paint
A. A microscope is the most important instrument for locating and
comparing paint specimens
B. Color is the most distinctive forensic characteristic of paint
C. An examiner observes color layers and tries to match the number and
sequence of colors. This process can connect paints to a common
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origin
D. Unfortunately, most paint specimens do not have layers that can be
individualized to a single source, so a chemical analysis must be done
III. Techniques Used in Paint Comparisons
A. Characterization of paint binders
1. Pyrolysis gas chromatography
a) Many solids cannot be injected into a gas chromatograph, so
items must be heated, or pyrolyzed, to high temperatures so
that they will decompose into gaseous products
b) Then they are put into a chromatograph, and a pyrogram is
produced showing the chemical makeup of the binder
c) Even the smallest of paint chips can be pyrolyzed and sent
through the gas chromatograph
d) Pyrograms can distinguish one polymer from another
2. Infrared spectrophotometry
a) Binders absorb infrared radiation to yield a spectrum that is
characteristic to that specimen
B. Characteristics of paint pigments
1. Emission spectrograph
a) Can detect 15 – 20 elements in auto paint simultaneously
b) Some are common to all paints, but others have significant
forensic uniqueness
IV. Significance of Paint Evidence
A. How to tell if two similar paints come from the same surface
1. Paint layers beneath the surface layer offer valuable points of
comparison
2. Color charts for automobile finishes are available from
manufacturers
3. Paint Data Query (PDQ)
a) A database that provides information on paints based on
make, model, and year
b) Maintained by the Royal Canadian Mounted Police
V. Collection and Preservation of Paint Evidence
A. Paint evidence is mostly involved in burglaries and hit-and-run
incidents
B. Paint chips should be picked up with forceps and placed in a paper
druggist fold or a glass or plastic container
C. If the paint is smeared on or embedded into something, package the
entire item
D. With hit-and-run cases, collect uncontaminated paint from an
undamaged area as a reference for comparison
E. ¼-inch square samples are sufficient, but you must go all the way to
the bare metal
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Activities
1. Forensic Paint Crossword Puzzle. Have students review forensic paint
analysis terminology by completing the Forensic Paint Crossword. It may
be helpful to allow students to use their lecture notes. Use the Forensic
Paint Crossword Puzzle Key for assessment.
2. Paint Layer Determination (this is a 2-day assignment). Prepare and
distribute the materials before class. Divide the class into four groups (A,
B, C, and D). Have the students create paint samples according to the
procedure for Day 1 of the Paint Layer Determination Lab. For Day 2,
have students analyze the samples and answer the lab questions
(although they are working in groups, the students should complete the
Day 2 work individually). See the Paint Layer Determination Lab Teacher’s
Notes and the Paint Layer Determination Lab for details. Use the Paint
Layer Determination Lab Key and/or the Individual Work Rubric for
assessment.
Assessments
Forensic Paint Analysis Quiz and Key
Forensic Paint Crossword Puzzle Key
Paint Layer Determination Key
Discussion Rubric
Individual Work Rubric
Presentation Rubric
Materials
Forensic Paint Analysis computer-based presentation
Forensic Paint Crossword Puzzle and Key
Paint Layer Determination Lab
 Paint Layer Determination Lab handout (one per student)
 Paint Layer Determination Lab Teacher’s Notes
 Paint Layer Determination Lab Key
 4 index cards (3x5)
 4 different colors of poster paint (to be shared among the 4 groups)
 4 sponge paintbrushes (one for each color paint)
 4 re-sealable sandwich bags (one for each group)
 Scissors (for each group)
 Forceps (for each group)
 Hand lenses or stereoscopic microscopes (for each group)
 Scrap paper or newspaper
 Colored pencils
Resources
Saferstein, Richard. Forensic Science: An Introduction. New Jersey:
Pearson Prentice Hall, 2008
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Saferstein, Richard. Forensic Science: An Introduction. 2nd ed.
New Jersey: Pearson Prentice Hall, 2011
Saferstein, Richard. Criminalistics: An Introduction to Forensic Science.
8th ed. Upper Saddle River, NJ; Pearson Prentice Hall, 2004B
http://en.wikipedia.org/wiki/Murder_of_Vicky_Lynn_Hoskinson
Accommodations for Learning Differences
For reinforcement, students will write 3 test questions from the class notes
and present them to the class. The questions must be one of each of the
following: multiple choice, true/false, and completion. Use the Presentation
Rubric for assessment (Note: The students’ questions may be used as
additional items on the quiz or even as bonus questions).
For enrichment, students will match paint chips to a crime scene sample.
Obtain 3 to 4, ¼-inch sized paint chips from various items. Sources could
include paint from houses, old bicycles, wrecked vehicles, etc. This activity
will be more “authentic” if you use the same type of paint source (for example,
three paint chips that come from 3 different red vehicles). Make sure you
obtain 2 samples from each to allow for the crime scene sample. Label the
crime scene sample and then label the other samples “Sample A,” “Sample
B,” etc. Using the microscopes and the hand lenses, students are to try to
determine which sample matches the crime scene sample. Use the Individual
Work Rubric for assessment.
State Education Standards
Texas Essential Knowledge and Skills for Career and Technical Education
§130.295. Forensic Science (One Credit).
(1)
The student, for at least 40% of instructional time, conducts
laboratory and field investigations using safe, environmentally
appropriate, and ethical practices. These investigations must
involve actively obtaining and analyzing data with physical
equipment, but may also involve experimentation in a simulated
environment as well as field observations that extend beyond
the classroom. The student is expected to:
(A)
demonstrate safe practices during laboratory and field
investigations; and
(B)
demonstrate an understanding of the use and
conservation of resources and the proper disposal or
recycling of materials.
(2)
The student uses scientific methods and equipment during
laboratory and field investigations. The student is expected to:
(F)
collect and organize qualitative and quantitative data and
make measurements with accuracy and precision using
tools such as calculators, spreadsheet software, datacollecting probes, computers, standard laboratory
glassware, microscopes, various prepared slides,
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(3)
(5)
stereoscopes, metric rulers, electronic balances, gel
electrophoresis apparatuses, micropipettors, hand
lenses, Celsius thermometers, hot plates, lab notebooks
or journals, timing devices, cameras, Petri dishes, lab
incubators, meter sticks, and models, diagrams, or
samples of biological specimens or structures;
(G)
analyze, evaluate, make inferences, and predict trends
from data; and
(H)
communicate valid conclusions supported by the data
through methods such as lab reports, labeled drawings,
graphic organizers, journals, summaries, oral reports, and
technology-based reports.
The student uses critical thinking, scientific reasoning, and
problem solving to make informed decisions within and outside
the classroom. The student is expected to:
(A)
in all fields of science, analyze, evaluate, and critique
scientific explanations by using empirical evidence,
logical reasoning, and experimental and observational
testing, including examining all sides of scientific
evidence of those scientific explanations, so as to
encourage critical thinking by the student;
(D)
evaluate the impact of scientific research on society and
the environment;
(E)
evaluate models according to their limitations in
representing biological objects or events; and
(F)
research and describe the history of science and
contributions of scientists.
The student recognizes the procedures of evidence collection
while maintaining the integrity of a crime scene. The student is
expected to:
(C)
conduct a systematic search of a simulated crime scene
for physical evidence following crime scene protocol;
(E)
describe the elements of a crime scene sketch such as
measurements, compass directions, scale of proportion,
legend, key, and title;
(F)
develop a crime scene sketch using triangulation,
rectangular coordinates, straight-line methods, and use of
coordinates on transecting baseline;
(G)
outline the chain of custody procedure for evidence
discovered in a crime scene;
(H)
demonstrate proper techniques for collecting and
packaging physical evidence found at a crime scene;
(I)
explain the functions of national databases available to
forensic scientists; and
(J)
collect and preserve physical evidence from a simulated
crime scene.
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(6)
(7)
The student analyzes the evidence collected from a crime scene
using scientific methods. The student is expected to:
(A)
demonstrate conversions of measurements between
English and International System (SI) of units;
(B)
distinguish between physical and chemical properties of
matter using the periodic table;
(C)
determine the elements within a compound or mixture;
(D)
identify the four types of chemical reactions;
(G)
identify the light sources used in forensic science such as
ultraviolet light;
(H)
explain the examination of trace evidence using
instruments such as a spectrophotometer, stereoscope,
electron microscope, and compound microscope;
The student recognizes the methods to process and analyze
trace evidence commonly found in a crime scene. The student is
expected to:
(A)
perform continuous and light emissions laboratory
procedures to identify trace evidence;
College and Career Readiness Standards
Science Standards
I. Nature of Science: Scientific Ways of Learning and Thinking
C. Collaborative and safe working practices
1. Collaborate on joint projects.
2. Understand and apply safe procedures in the laboratory and field,
including chemical, electrical, and fire safety and safe handling of live
or preserved organisms.
3. Demonstrate skill in the safe use of a wide variety of apparatuses,
equipment, techniques, and procedures.
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Name________________________________
Date______________________
Forensic Paint Analysis Quiz
Matching
_____1. The most important instrument for comparing
paint chips
A. Basecoat
_____2. The layer of automobile paint that contains the
actual color of the vehicle
B. Binder
_____3. A component of paint that is dissolved or
dispersed in a solvent
C. Clearcoat
_____4. The unpigmented paint layer that adds gloss and
durability
D. Color
_____5. Something an examiner would observe to match
the number and sequence of colors
E. Electrocoat Primer
_____6. The most distinctive forensic characteristic of
paint
F. Emission Spectrograph
_____7. The layer of automobile paint that hides
imperfections
G. Hit-and-Run
_____8. The process of heating a paint sample to high
temperatures until it transforms into a gas
H. Infrared
_____9. Radiation absorbed by paint binders to yield a
spectrum that is unique to a specimen
I. Microscope
____10. One of the most common types of crime in which
paint analysis is used
____11. The database that provides information about
automobile paint
____12. The layer of automobile paint applied directly to
the steel body for corrosion resistance
____13. Capable of detecting 15 – 20 elements in auto
paint simultaneously
____14. Should be collected from an undamaged area as
a reference for comparison in a hit-and-run case
____15. The minimum size of a paint sample for analysis
J. Paint Data Query
K. Paint Layers
L. Primer Surfacer
M. Pyrolysis
N. Quarter-inch
O. Uncontaminated Paint
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Forensic Paint Analysis Quiz Key
1. I
2. A
3. B
4. C
5. K
6. D
7. L
8. M
9. H
10. G
11. J
12. E
13. F
14. O
15. N
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Name________________________________
Date______________________
Forensic Paint Crossword Puzzle
8
6
2
4
3
5
1
9
7
10
Across:
1. Unpigmented paint layer; adds gloss and
durability
5. Paint is composed of pigments and a _____
6. The most important instrument for
comparing paint chips
7. When a paint sample is heated to high
temperatures until it transforms into a gas
10. Most common type of crime where paint
analysis is utilized
Down:
2. Paint layer; hides imperfections
3. Absorbed by binders to yield a spectrum
that is unique to a certain specimen
4. Examiner matches number and sequence of
colors
8. Paint layer; actual color of a vehicle
9. The most distinctive forensic characteristic
of paint
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Forensic Paint Crossword Puzzle Key
8
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Across:
1. Unpigmented paint layer; adds gloss and
durability (clearcoat)
5. Paint is composed of pigments and a _____
(binder)
6. The most important instrument for
comparing paint chips (microscope)
7. When a paint sample is heated to high
temperatures until it transforms into a gas
(pyrolysis)
10. Most common type of crime where paint
analysis is utilized (hitandrun)
Down:
2. Paint layer; hides imperfections
(primersurfacer)
3. Absorbed by binders to yield a spectrum
that is unique to a certain specimen
(infrared)
4. Examiner matches number and sequence of
colors (paintlayers)
8. Paint layer; actual color of a vehicle
(basecoat)
9. The most distinctive forensic characteristic
of paint (color)
10
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Name________________________________
Date______________________
Paint Layer Determination Lab
Rationale:
Oftentimes, paint consists of several layers of different substances, as is the case with
automobile paint, or it may be several layers of different colors painted on top of one another. In
the event that a paint chip is a piece of evidence, it may need to be compared to a known
sample. Observation of paint layers is the first step in completing the comparison and does not
destroy the sample as other methods of determination can. This activity provides an opportunity
to observe and compare paint layers.
Materials (needed per group):
 3x5 cards, 1 per group
 Piece of scrap paper or newspaper
 4 different colors of poster paint (or 1 color for each group, and they trade off)
 4 sponge paintbrushes (1 per color)
 Resealable sandwich bag
 Scissors
 Hand lens or stereoscopic microscope
 Forceps
 Colored pencils
Procedure (Day 1):
1. Place the 3x5 card on the piece of scrap paper or newspaper
2. Using the appropriate paintbrush, paint the entire surface of the card with one color of paint
3. Allow the paint to dry (it will dry faster if a hairdryer, fan, or incubator is available)
4. Once the paint is dry, choose another color and an appropriate paintbrush, and paint over the
entire surface of the previous color
5. Repeat the steps until all 5 colors have been used (the sequence of colors used should be
random among the groups)
6. When the card is completely dry, cut it into 8 equal pieces as illustrated
7. On the back, label 4 pieces with your group letter and leave the other 4 blank
8. Place all 8 pieces into the plastic bag and turn it in to the instructor
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Procedure (Day 2):
1. Pick up a plastic bag and remove the contents using forceps. You will find 1 piece from each
group (A – D) and one labeled Crime Scene
2. Using either a hand lens or the stereoscopic microscopic, observe the different layers of paint
3. Compare each of the 4 group cards to the crime scene to see which one matches it
4. In the appropriate column, draw horizontal lines in colored pencil to represent the layers
5. Answer the questions that follow
PAINT “CHIP” LAYERS
Group A
Group B
Group C
Group D
Crime Scene
Top
Bottom
Questions:
1. Did you determine which group matched the crime scene sample? If so, which one? If not,
why?
2. Is it possible for the crime scene sample to match more than one group? How could that
happen?
3. Would observation of paint layers alone be enough to determine an exact match? Explain
your answer.
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Paint Chip Determination Lab
Teacher’s Notes
Review the Paint Chip Determination Lab materials. Use the following notes to prepare and lead
the lab activity:
 If possible, make sure each group has a different sequence of paint layers. However, it is
more challenging to have them all end up with the same color on top so they cannot
automatically determine a match. If you choose, more paint color layers could also be used.
 After Day 1, remove all 8 samples from each bag. For the ones that have the group letter,
divide them into 4 groups, each containing A – D.
 For the remaining blank samples, choose one group to be the “crime scene.” On the back of
those 4, write, “Crime Scene.”
 Discard all of the groups’ blank samples.
 When the samples are dispersed to the students for Day 2, each group should have 5
samples: A – D and a Crime Scene.
 Place the cards back into the bags and distribute them to the groups to complete the lab
procedure.
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Paint Chip Determination Lab Key
1. Answers will vary depending on the class. Although it is tedious, students should be able to
match the sample to the crime scene.
2. Yes, it is possible to have more than one group match the crime scene if the layers were
painted in the same sequence. This could happen in reality, such as with cars that happened
to be painted more than once with the same sequence of colors.
3. It would be difficult to allow color layers alone to be considered an exact match for reasons
such as the explanation in #2 above. However, sometimes paint chips have a particular
shape that may be matched to the source, much like a jigsaw puzzle. Most likely, if layers
match a source, further testing would determine exactness.
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Name_______________________________________
Date_______________________________
Discussion Rubric
Objectives
4 pts.
Excellent
3 pts.
Good
2 pts. Needs Some
Improvement
1 pt. Needs Much
Improvement
N/A
Pts.
Participates in group discussion
Encourages others to join the
conversation
Keeps the discussion progressing
to achieve goals
Shares thoughts actively while
offering helpful recommendations to
others
Gives credit to others for their ideas
Respects the opinions of others
Involves others by asking questions
or requesting input
Expresses thoughts and ideas
clearly and effectively
Total Points (32 pts.)
Comments:
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Name______________________________________
Date_______________________________________
Individual Work Rubric
4 pts.
Excellent
Objectives
3 pts.
Good
2 pts. Needs Some
Improvement
1 pt. Needs Much
Improvement
N/A
Pts.
Follows directions
Student completed the work as directed,
following the directions given, in order and to the
level of quality indicated
Time management
Student used time wisely and remained on task
100% of the time
Organization
Student kept notes and materials in a neat,
legible, and organized manner. Information was
readily retrieved
Evidence of learning
Student documented information in his or her
own words and can accurately answer questions
related to the information retrieved
*Research/Gathering information (if relevant)
Student used a variety of methods and sources
to gather information. Student took notes while
gathering information
Total Points (20 pts.)
Comments:
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Name:____________________________________
Date:_____________________________
Presentation Rubric
4 pts.
Excellent
Objectives
3 pts.
Good
2 pts. Needs Some
Improvement
1 pt. Needs Much
Improvement
N/A
Pts.
Topic/Content
 Topic discussed completely and in-depth
 Includes properly cited sources (if used)
Creativity/Neatness
 Integrates a variety of multimedia effects
to create a professional presentation
(transition and graphics) or appropriate
visual aid used
 Title slide, table of contents, bibliography
are included, using acceptable format
Mechanics
 Grammar, spelling, punctuation, and
capitalization are correct
 Image and font size are legible to the
entire audience
Oral Presentation
 Communicates with enthusiasm and eye
contact
 Voice delivery and projection are
dynamic and audible
Audience Interaction
 Presentation holds audience’s attention
and relates a clear message
 Clearly and effectively communicates the
content throughout the presentation
Total Points (20 pts.)
Comments:
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