1. DECEMBER 4, 2012
EQ: How can synthetic fibers be used to solve crimes?
WARM-UP:
The following slide will have 9 pictures (A-I). Identify the animal hair shown and answer the questions. You may use the pgs in Ch 10 (blue)/11 (orange) of your book.

2. Can you identify the animal hairs shown?B C D G E F H I
Teacher Note: I challenge students to identify each hair sample pictured on this slide as they examine the sets of animal hairs I have prepared for them. An observation worksheet is available on my website which requires students to draw an image of what they see and add a description that highlights unique characteristics of each specimen. A key for the animal hairs is available on the next to last slide of this presentation!
Think About It …
In which samples are we viewing the cuticle? How do they compare?
(2) In which samples are we viewing the medulla? How do they compare?
(3) What characteristics can be used to identify hair samples?

3. Types of Animal Hairs - Key
Cat
Horse
Pig
Human A B C D G E F H I
Deer
Dog
Rabbit
Rat
Human
All
All but two (B & I)
Medulla absent or present, shape of medulla, cuticle, diameter of medulla, etc.

4. Microscopic Evidence and Its Analysis
- Root Characteristics: Removal
Pulled
Forcibly removed
Shed
- Tip Characteristics
Burned
Cut
Razored
Split

6. Fiber Evidence
A fiber is the smallest unit of a textile material that has a length many times greater than its diameter.
Matching unique fibers on the clothing of a victim to fibers on a suspect’s clothing can be very helpful to an investigation.
The discovery of cross transfers and multiple fiber transfers between the suspect's clothing and the victim's clothing dramatically increases the chances that these two individuals had physical contact.

7. Natural Fibers
Many different natural fibers that come from plants and animals are used in the production of fabric. (Wool, mohair, cotton, cashmere, mink, etc.)
Cotton fibers are the plant fibers most commonly used in textile materials. Cotton fibers have a ribbon-like shape with twists at irregular intervals.
The animal fiber most frequently used in the production of textile materials is wool, and the most common wool fibers originate from sheep.

8. What are some common natural fibers that come from animals?

9. Synthetic (Manufactured) Fibers
More than half of all fibers used in the production of textile materials are synthetic or man-made.
Nylon, rayon, spandex, and polyester are all examples of synthetic fibers.
Fibers under a microscope
Cross-section of a man-made fiber
Images:

10. 5 Characteristics used to identify Fibers:
Color (comparison microscope)
Diameter (comparison microscope)
Lengthwise striations
Pitting of fibers surface
Cross-sectional shape

11. More than half of which fibers are used to make fabrics?

12. Analytical Techniques used in Fiber Examination:
Visible-light micro spectrophotometer-
compare colors of fivers through spectral patterns
Chromatography-
Separating colors in dyes that come from the fibers for comparison
Chemical composition-
Test for chemical make-up of fibers to see if they are in the same class
Birefringence-
Double refraction (two bends), when substance is melted & crystallized
Infrared Light-
Use of a microscope and infrared spectrophotometer for infrared analysis

13. 3 Challenges in Identifying Fiber Evidence:
No analytical technique to trace a fiber to a single garment with certainty
No databases for fibers origin
Mass distribution of fibers and changing fashions

14. Collection & Preservation of Fiber Evidence:
Clothing packaged in paper bags
Carpet, rugs, & bedding folded carefully
Articles shouldn’t be placed on same surface
Loose fibers removed and placed on paper, folded and labeled

15. Which fiber analysis technique involves separating dyes to see patterns of color?

16. HAIR & FIBERS DRAWINGS:
Draw the following fibers and include the following:
Specimen name (Dog, cat, etc.)
Magnification (100x, 400x, etc.)
Contain a Medulla
Is medulla continuous, fragmented, or interrupted?
HAIR:
Human
Dog
Deer
Rabbit
Cat
Mouse

17. Draw the following NATURAL & SYNTHETIC fibers as seen under a microscope and include the following:
Specimen
Magnification
One characteristic
Uses (at least two)
Cotton
Wool
Mohair
Rayon
Polyester
Spandex

19. Can you identify the types of fibers shown?
Teacher Note: I challenge students to identify each fiber sample pictured on this slide as they examine the sets of fibers I have prepared for them. An observation worksheet is available on my website which requires students to draw an image of what they see and add a description that highlights unique characteristics. A key for the fibers is available on the last slide of this presentation!
Think About It …
Which samples are natural fibers?
(2) Which samples are synthetic fibers?
(3) What characteristics can be used to identify fiber samples?

20. Answer Keys

21. A B C D E F Types of Fibers - Key Acrylic Yarn Cotton Yarn Nylon Rope
Polyester Yarn
Rayon Rope
Wool Yarn