Forensics World Of Fibers
Wide World of Fibers
The whole aim of this experiment was to identify and analyzes fibers in a forensic laboratory, and to see their reactions in different conductions.
The main purpose is to try to find what the unknown fiber was among different fibers. The fibers which were used in this lab were acetate, cotton, nylon 6.6, silk viscose and wool. Many of these fibers are from natural fibers. Natural fibers are from living things like the cotton plant, silk worm, goats, and sheep, these animals contribute in producing cotton, linen, and nylon 6.6 and silk. Many others fibers are also manufactured chemically are called synthetic fibers. The first part of this lab was to determine the texture and color of each fiber, secondly burning different fibers to see their reaction, thirdly perform a solvent test where each fiber was tested in different solutions, forth viewing the stained fibers under a microscope. Data tables were used for recording the result of each fiber. And also illustrates what the unknown fiber was. In the analysis talks about how the fibers were analyzed and persevered in Forensic Science, and also how to go about finding our unknown fiber. In the conclusion show what was learned and also gives a brief knowledgeable explanation of how this lab could have been better structured and states all the inconsistencies.
According to Webster dictionary fibers are: “a thread or a structure or object resembling a thread”. There are varies types of fibers like; man-made fibers, mineral fibers, polymer fibers, and micro fibers.
There are many ways of persevering and storing. According www.fbi gov.com fiber can be collected using a vacuum technique, where only fibers are being vacuumed for further observations. According to “Richard Saferstein, PhD author of the book Criminalistics” states that fibers should be wrapped and packaged in folder paper or pillbox and edge should be seal with tape.
In forensic classes many cases were studied and viewed which involving fibers. For example: the “Atlanta child murder case”. According to the Crime library this case had over 28 fibers pieces which were found on 19 out of 21 victims”. They claimed “It was hard to analyze the fibers because there were too many different fibers to connect to one specific suspect. Another cases studied was the Jeffery Mc Donald case which also involved fibers, fibers which were to solve this particular case.
I think that the unknown fiber is cotton. The purpose of this lab experiment is to have a better understanding of how Forensic Scientist analyzes fibers using various techniques and methods. Also to have a better view of fibers in different case situations like what happens when a fabric is burnt or when it is stained.
Materials and Methods
We have conducted many fiber experiments in odder to see what will happened to fibers in various cases. The following materials were used; data tables, fibers, forceps, candles, solvents, microscopes and stain.
Fibers like acetate, cotton, nylon 6.6, silk, viscose, wool, and an unknown fiber was used as examples in analyzing the colors, textures, and smell before testing. Forceps were used to hold and pick up fibers. Each fiber was attached and orderly labeled on to a sheet paper for testing.
Each fiber was placed near the fire and was recorded, and then it was placed direct into fire which was recorded also in odder to test the odor and residue.
Each fiber was tested in all three solvent, which were recorded to see what happens when chemicals are added to fabrics and recorded in a data table.
Fibers were placed in a boiling stain solution for 5 mins, then were removed and rinsed in hot water and was dried in a paper towel. And fibers were examined for color change. Prepare a wet mount with the stained fibers and view fibers under microscope to see texture and structure of each fiber.
Table 1:1 (show the different fiber which were used in this lab)
Table 1:2 (illustrates the reaction of burnt fibers)
Exercise A: burn test Acetate Cotton Nylon 6.6 Silk Viscose Wool Unknown
Approach flames Slowly burns Moved away from flame Disappeared Curled up Burned up Melt quickly Dissolve quickly
Burning reaction Burned very fast Spin away and burned Burn at neutral rate Burn fast Caught fire Curl, light up Melted and disappeared
Odor None Smell like burn hair Has no smell Popcorn New carpet Fiery smell Smell like Burn rice
Hard knot at tip Hard balled tip Soft and sticky Ashy black tip Ashy brown tip Black ball Formed back ball
Table 1:3 (shows the reactions of each fiber in different solvents)
Exercise B: Solvent test Acetate Cotton Nylon 6:6 Silk Viscose Wool Unknown
Remain the same Became straight greenish Remain the same Dissolved Stay the same Solution dried up Loose and turn green
Hydrochloric acid (HCL) Solution dissolved Remain the same Became thinner Became thinner Remains the same Creamy substance Remains the same
Sodium hypochlorite Shrieked got smaller No reaction loose Turned yellow Became loose Creamy substance Remains the same
Tables 1:4(show the results of stain fibers test view with the naked eye)
Exercise c: stain test Acetate Cotton Nylon 6.6 Silk Viscose Wool Unknown
Color before stain White White White Creamy White White White and creamy
texture Soft Soft Soft Black
Color while being stained Dark purple Purple Black
Light purple Dark purple Purple
Color when dried and texture Orange red and silky Light Purple and soft Dark blue and soft Black purple and soft Light purple and soft blue and soft Light purple and hard
Tables 1:5(show the results of stain fiber viewed under a microscope)
Exercise D: microscope test Acetate
Cotton Nylon 6.6 Silk Viscose Wool unknown
Folds or twist Twist Twist Twist Twist Fold Twist Twist
Transparent or opaque opaque opaque opaque opaque Transparent Transparent opaque
After doing the actual experiments for each station, many questions were formulated in order to fully understand the concept of this lab.
How do we collect fibers for a fiber analysis? The fist station of this lab was to carry out a small experiment to determine which fibers belong to what group. The first step is to collect one strand of fiber from each fabric with forceps and orderly arrange them in proper other to carry out the experiment without any inconsistencies. For Example Table 1:1 on page 5.
Can a burn test be used to analyze fibers? Yes, a burn test can be used to analyze fibers. For example in Table 1:2 a burnt test experiment was carried out in odder to determine what the unknown fiber was? Results, shows that the unknown fiber matches the cotton fiber which proves that a burn test can be used to determine and analyze fibers.
How can a solvent test be used to analyze fibers? A solvent test can be used to analyze fibers. After doing the solvent test which is testing different fibers to determine the unknown fiber it was found in Table 1:3 that the unknown fiber reacted the same way as the cotton fiber, which concludes that a solvent test can be used to analyze different fibers.
How can a stain test be used to analyze fibers? A stain test can be used to analyze fibers be color testing each fiber to determine which fiber reacts and has the same color another fiber.
How can a microscope be used to analyze fibers? It has been proven in table 1:5 that a microscope can be used to analyze fiber by detecting the color and texture through a microscope, which shows what fiber relates to the unknown fiber.
Hypothesis: I think that the unknown fiber is cotton.
My hypothesis was proven based on data tables of 1:1 and 1:4. In these tables it shows how the data from cotton matched the data result of the unknown, which prove that the unknown fiber is cotton. In this lab I learnt how to analyze fiber for different experiments including: burning fibers, testing solvent and viewing fibers under a microscope for further analysis, and also stain testing fibers.
Although this was a successful lab it still had many errors and consistency. For example failure to finish on time, which can be major problem because evidence may be needed immediately in solving a particular crime or case, also not enough fiber evidence were collected and persevered properly which can also be a major disappointment because evidence maybe destroyed and can be needed in court or further investigation. In future experiments I would have a better plan or structure on how to analyze fibers, and collecting enough fiber evidence for experiment.
Fiber evidence is very important in forensic science. Fibers in many case have solve many crimes over the years. In many cases if there isn’t any really evidence like blood, semen or a weapon, and only trace fibers are left at the crime scene, then the case can be solved using only the fiber evidence that was found. In forensic there are many ways to analyze fibers and determine what they are. Like stain testing them, burning, physically touching them, and also viewing them under a microscope.
Bardsley, M. & Bell, R. (2006) Atlanta Child Murders. Retrieved February 20, 2008, http://www.crimelibrary.com/serial_killers/predators/williams/index_1.html
Saferstein Phd., R. (1977) Criminalistics. 8th edition, New Jersey: Prentice Hall.