FSC 240L (LAB)-Fiber Analysis-USM

What is fiber identification based on?

Burning characteristics, solubility, staining, and microscopic appearance.

What type of evidence are fibers considered in forensics?

Class evidence — they can be associated with a group, not an individual.

Why are fibers class evidence?

Because they are mass-produced and can't be traced to a specific source.

What are fibers?

The basic units or building blocks of fabrics and textiles.

Where are fibers most commonly found as evidence?

At crime scenes, as a form of trace evidence linking people or objects.

What are the two main types of fibers?

Natural and man-made.

What are the three categories of natural fibers?

Mineral, plant, and animal.

Give examples of mineral fibers

Asbestos and glass wool.

Give examples of plant fibers.

Cotton, flax, and hemp.

Give examples of animal fibers.

Wool and silk.

What are the two categories of man-made fibers?

Derived and synthetic.

Give examples of derived fibers.

Rayon and acetate.

Give examples of synthetic fibers.

Nylon, Kevlar, and spandex.

What are the four common forensic tests for fiber analysis?

Microscopic analysis, burn test, solvent (chemical) test, and stain test.

What happens when fibers are exposed to heat and flame?

They may melt, curl, shrink, or burn depending on their type.

What does the odor from burning fibers indicate?

The fiber's composition (e.g., burning hair smell = animal fiber).

What types of residues can burning fibers leave?

Soft ash-like, brittle, or hard bead-like residues.

What are destructive tests?

Tests that destroy the sample during analysis (e.g., burn and solvent tests).

What are non-destructive tests?

Tests that do not destroy the sample (e.g., microscopy and stain tests).

What chemicals are used in the fiber solvent test?

Acetone, hydrochloric acid, and sodium hypochlorite.

What does the solvent test determine?

Whether a fiber dissolves, is damaged, or remains unchanged by chemicals.

What is the purpose of the stain test?

To see how different fibers absorb dye based on chemical composition.

What can microscopic analysis reveal about fibers?

Shape, texture, striations, twists, folds, transparency, and color.

What are striations?

Longitudinal or cross markings seen on fibers under a microscope

What materials are used in fiber identification labs?

Acetone, hydrochloric acid, sodium hypochlorite, vinegar, Fiber ID stain, microscope, slides, test tubes, forceps, candle, and hot plate.

What safety equipment is required during fiber testing?

Gloves, goggles, and lab coats (especially for burn and chemical tests).

What are the six fibers typically tested in the multi-fiber fabric?

Acetate, cotton, nylon, silk, viscose (rayon), and wool.

In the burn test, how should the fiber be brought to the flame?

Horizontally from the side — never from above.

What are you observing in the burn test?

Reaction to flame, rate of burning, odor, and type of residue.

What should be noted in the solvent test?

Whether fibers dissolve, change color, or remain unaffected.

What does the stain test involve?

Boiling fibers in Fiber Identification Stain and vinegar, then rinsing and drying.

What are you recording after the stain test?

The color and luster (shininess) of each fiber.

What does the microscopic examination require?

A water-mounted slide of each fiber observed under low and high power.

What should be noted under the microscope?

Striations, folds, transparency, twists, and overall fiber shape.

What is the goal of Activity 2 in the Fiber Identification Kit?

To identify an unknown fiber using various tests.

Why should test order be chosen carefully when analyzing unknown fibers?

Because you have only one sample — destructive tests will eliminate it.

What two tests are most helpful in identifying fibers?

Burn test and microscopic analysis (combined results confirm identity).

Why are fibers important forensic evidence?

They can link a suspect or victim to a scene through trace transfer.

What case famously used fiber evidence to convict a criminal?

The Wayne Williams case (Atlanta serial killings).

Why are man-made fibers considered superior in some uses?

They can be designed to be wrinkle-resistant, waterproof, or quick-drying.

What physical property makes fibers identifiable?

Their high length-to-width ratio and polymer composition.

How do delustering agents affect fibers?

They make shiny man-made fibers appear speckled under a microscope.