Fibers

Carolina bonnetNicole SalvadorPeriod 4

What are Fibers O_oA Fiber is the smallest unit of a textile material that has a length many times greater than its diameter.

• Fibers can be spun with other fibers• The type and length of the fiber used, the type of spinning method and the type of fabric construction all affect the transfer of fibers and sign of the fiber association.• There is a possibility of fiber transfer between a suspect and a victim during the commission of a crime

Types of FibersNatural fibers : Fibers that come from plants Silk Cotton Wool Cashmere Mohair

Synthetic fibers: Man made fibersRayonNylonAcetate AcrylicSpandexPolyester

Mineral Fibers: Made from natural or synthetic minerals or metal oxidesAsbestosRockwoolFiberglass

About Them…Silk- The soft, lustrous fiber obtained as a

filament from the cocoon of the silkworm.

Cotton- Vegetable fiber; strong, tough, flex & moisture absorbent.

Rayon- Chemically alerted cellulose; soft, lustrous

Nylon- Most durable of man made and very light weight.

Acrylic- provides warmth from a light weight soft and resilient fiber Spandex- Extreme elastic prop.

Polyester- Most widely used man made fiber.

Visual

Weave PatternsPlain- Simplest most common Weave

Twill- looks like stair steps.

Satin-creates long floats interlacing. Passes over 1 or more yarns.

Testing fibersBurning- How fibers burns, odor, color of flame & color of smoke.

Thermal Decomposition- gently heating to break down the fiber to the basic monomers.

Chemical Test- Solubility & Decomposition.

DyesComponents that make up dyes can be separated and matched to an unknown.

Chromatography is used to separate dyes.

* (7,000 diff. dye formulations)

Packaging evidence

When collecting fibers, You must be very careful. As this evidence is difficult to be seen with the naked eye. It is important to have somebody at the scene to specifically look for these clues. Each piece of clothing that could contain relevant fibers and should be bagged separately in paper bags. *Every item must be bagged separately to avoid the chance of cross-contaminating the actual evidence. *All articles such as carpets, rugs, and bedding should be individually folded and packaged to protect the fiber evidence. *If a fiber has to be removed to keep it preserved, It should be removed with forceps and placed in a small sheet of paper. *Once its folded and labeled, it should be put in another container to keep it safe.

In 1992 a police expert, Francis X. Callery, testified that 3 strands of hair found on the clothing of a victim, 14-year-old Shamira Bello, matched that of Mr. Henriquez. fibers were also found on three victims. These matched those in a vacuum cleaner in Mr. Henriquez's apartment or on a spool of red thread that due to other testimony had been in his apartment. Four weeks later after the trial Mr. Henriquez, a 31-year-old livery-car driver, was accused of killing three young victims whom he became friends with, in his Bronx neighborhood: Shamira Bello, Jessica Guzman, 10, and Lisa Ann Rodriguez, 21.

Solved Case

Test Your Knowledge1. What is Chromatography used for?

2. What is the simplest most common weave?

3. __________ is the Most durable fabric and is man made and very light weight.

4. Can fibers be spun together with other fibers?

5. What type of fiber is Spandex?

How To Use A Microscope

1.Turn the revolving nosepiece so that the lowest power objective lens is being used .2.Put the cover slip on the slide to protect your slide3.look through the eyepiece & adjust the illuminator.4.Slowly turn the coarse adjustment so that the objective lens goes up. Do this until the image comes to attention.5.Use the fine adjustment for better focusing and you can also move the stage up or down using the coarse knob.

•REMEMBER to Always hold microscope by the arm & the base.

The EndMy Little Monsters!!!