Textiles

Question 1

Textiles are used in:

Answer 1

Clothing, home furnishings, upholstery, carpets, auto seats and end products.

• Natural or artificial origin
• Wide variety of methods used to turn fibers into fabrics

Question 2

Fiber is:

Answer 2

• The most fundamental unit of a fabric.
• Grouped according to origin (natural or artificial)
• Elongated structure whose length exceeds its breath

Question 3

Natural fibers are:

Answer 3

1. Animal
2. Mineral
3. Vegetable

Question 4

Animal fiber is:

Answer 4

Keratin based, (sheep, wool, any fur type)

Non-keratin based (cultivated silk and wild silk)

Question 5

Mineral fiber is:

Answer 5

Asbestos fibers

Question 6

Vegetable fiber is:

Answer 6

Seed, cotton, coconut; leaf, bast (flax and hemp);

Question 7

Artificial fiber is:

Answer 7

• Originate from natural substances and are truly synthetic.
• Polymers of long chains of basic chemical units.
  Ex: rayon regenerated from natural substance; basic
  building block is cellulose.

Question 8

Fibers encountered in forensics:

Answer 8

Most common is Polyester (1/3 of global production).

Cotton is second most common.

Question 9

Fiber transfer types:

Answer 9

• Primary and Secondary

Question 10

Case management questions:

Answer 10

What is alleged to have taken place?
Who is involved and how?
Where it took place? House? Car? Who was occupant? Owner?
When did incident happen? Delay in scene examination?
Persons having access to scene?
Description of perpetrator’s clothing?

Question 11

Factors that effect transfer:

Answer 11

• Fiber type
• Fiber morphology and thickness
• Fiber texture and construction
• Area of contact
• Number of contacts
• Force or pressure of contact

Question 12

Within one fiber type, __________will transfer in greater numbers than coarser fibers.

Answer 12

Finer Fibers

Ex: wool, acrylic, cotton, polyester, nylon and viscose

Question 13

Fiber transfer:

Answer 13

Area of contact -more fibers will transfer from a coarse than a smooth fabric.
Number of contacts-transfer increases with number of contacts.
Force of pressure and contact-transfer increases with force or pressure of contact until plateau is reached. Greater exchange of short fibers.

Question 14

Fiber transfer types:

Answer 14

Primary-direct transfer from a donor item to a recipient item.
Secondary-indirect fiber transfer (subject B pickup fibers from a car seat left by subject A).

Question 15

Fiber persistence:

Answer 15

Whether or not fibers will be found after a transfer. Factors include: force of pressure of contact, location of contact, wearing of recipient garment and placement of recipient garment.

Question 16

Effect of fiber size and morphology:

Answer 16

Persistence of short fibers under 2.5mm in length is greater than longer fibers. Micro fibers have greater persistence compared with natural fibers.

Question 17

Target fibers are:

Answer 17

• sheddable and of color that is suitable for searching.
• recover with tape and searched for with low power microscopy
• fibers in color range as that of known target are marked for examination
• what happens next: microscopic examination, color analysis and ID

Question 18

Microscopy can determine fiber:

Answer 18

Color
Relative diameter
Crimp
Man made or natural

Question 19

Retardation is:

Answer 19

Synthetic fibers has different RI between parallel axis and perpendicular axis of the fiber. The difference is known as “Retardation Factor”.

Question 20

Retardation Factor (synthetic fibers):

Answer 20

If parallel RI>than perpendicular RI= “fiber has positive elongation”
If parallel RI

Question 21

Fiber damage:

Answer 21

Mechanical damage- cutting by sharp edged object.
Environmental damage- normal use.
Influence of high temperature-(and pressure).
Microorganisms- bacteria and fungi.

Question 22

“Mechanical” damage of fiber:

Answer 22

Normal wear and tear; takes the form of a thinning of the fabric prior to hole forming, pilling and unraveling of hems/seams,
tear, etc. In violent interactions, fabric maybe torn, seams fail and structure of fabric distorted.

Question 23

“Mechanical” damage of fabric include:

Answer 23

Cutting, slashing, puncturing, abrasion, tensile failure (seat belt);
insects, moths and microorganisms. By animals (pets).

Question 24

Information from fiber damage:

Answer 24

“Blade type and size;” more distinctive the weapon, the more unique characteristics. General observations include blunt tip, more fabric distortion around penetration point; sharp blade, cut
through without much distortion. Condition of blade, imperfections,
serrations, etc., will increase fabric distortion.