Characteristics Of The Polyester And The Fiber example essay topic

Picking Up The Pieces: A lab on Fiber Analysis Objective: To collect fiber evidence, then analyze it to identify its source. Procedure: 1. Collect a red fiber from the "victim" by carefully lifting the fiber with a pair of forceps. Do not touch the fiber with your hands. Place fiber on a piece of white paper, then fold the paper in half twice. 2.

Carry the fiber to your lab station. Prepare a wet-mount slide of the fiber by placing it on the slide, adding a drop of water, and covering the fiber and water with a cover slip. 3. Examine the fiber under low, medium, and high magnification of your microscope. Sketch what you see.

Note any pits or striations on the fiber. 4. Compare this fiber to known samples of wool, rayon, silk, and cotton. Sketch each of these samples at the magnification that gives you the best view and record these sketches here. 5.

Light your candle and compare the burning characteristics of the unknown fiber to the known samples. Record your observations on the Data Table. a. Holding the fiber in forceps, bring it close to, but not touching, a flame. Describe the fiber's behavior as it approaches a flame: does it begin to melt, ignite, curl? b. Holding the fiber in forceps, touch the fiber to a flame. Does it ignite quickly or slowly?

Does it sputter, drip, or melt? c. Remove the fiber from the flame and describe how it behaves. Does it extinguish. Continue to burn, or continue to glow? d.

Note any odor associated with the fiber in the flame. Does it smell like vinegar or hair? e. What kind of residue is left after the fiber is removed from the flame? Does the fiber leave a white, fluffy ash, a hard bead, or a melted blob? Data Analysis: Through careful examination of the crime-scene fibers, we have discovered the material typing. During the microscope examining we found that the fibers where very loose, and stringy.

During the burning test, we discovered that the material melted approaching the flame, and burnt and melted at the same time. It also drips with a plastic look to it, and smells like burning plastic. The residue left was a stringy melt. On the known fabrics we concluded that wool and cotton are very much the same. Both had stray fibers off of the main fiber. The rayon had very thick continuous weave.

The silk had a rather "spun" look to it, and last but not least the polyester was stringy and loose. During the burn test we discovered that wool was very slow to ignite as well as silk, rayon and cotton were quick to ignite, and polyester melted then ignited. Also wool and silk smelt like burning hair, cotton, and rayon smelt like burning leaves, and polyester smelt like burning plastic. The residue left by all of them was wool had a big blob that melted together, rayon had a slight ash left, silk had a hard beady ash crust, polyester had a stringy melt, and cotton left ash crumbles. Conclusion: In conclusion we have determined that Casey is the murderer. Through the evidence, and data analysis we conclude this in many ways.

The fibers found on the victim's body were that of polyester. During the burn test both fibers found on the victim and the known fiber, polyester, demonstrated similar characteristics. Among these are, they both melted when approaching the fire, smelt like burning plastic, and the residue left was a stringy melt. Through the microscope tests we determined that the characteristics of the polyester and the fiber found on the victims body were similar. Both had thin loose fibers and were both reddish-pink. How is it useful: Fiber analysis is important in many different ways.

One way it is important is if a crime was committed and stray fibers were left on the victim, a forensic scientist can study those fibers, link them to a person, place, or thing and help solve a crime, by placing suspects in attention. I learned during this lab that it is very important to pay close attention to the little details. In identifying a fiber it is very important to pay attention, because many fibers look the same to the naked eye, but with further examination they are much different.