Name_____________ Partner______________   Date___________

Dyes and Fabric Lab

Crime Scene:

          A man and his dog were attacked outside a construction site. The dog and man put up a good fight. The dog even ripped some of the clothing off the assailant. The evidence was in the form of a swatch of fabric.  In this investigation, you are going to look at the dye properties of the fabric fibers. You will dye a multi-fiber ribbon in an attempt to identify the fiber type that was used to make the fabric found in the swatch.

 

Procedure: Day1

  1. Collect 2 swatches from the crime scene (1 to dye /1 leave in the bindle). Use a bindle to store your swatch evidence. Label your bindle with your name and CS.
  2. Get a Multi-fiber ribbon from the Crime Lab Director.
  3. Use a microscope or lighted magnifier to record the appearance of the individual fibers in the fiber – record your observation in the data table # 1.
  4. Use a microscope or lighted magnifier to record the appearance of the individual fibers in the crime scene swatch. Record in data table # 2
  5. To a plastic cup add  50 ml of the “dye”  ( Kool-Aid, experimental dye #1 or2, Rite or Crystal light). Stir to dissolve with a plastic spoon.
  6. Use a marker to label your cup (put both your names on the cup). Place you cup at the side of the room.

 

Procedure: Day#2

  1. With forceps, remove your multi-fiber ribbon and place in a warm water bath – then quickly remove it and rinse with cold water. Use a paper towel to blot it dry.
  2. Repeat step 1 for the crime scene swatch.
  3. Use a microscope or lighted magnifier to record the appearance of the individual fibers in the fiber – record your observation in the data table # 1.
  4. Use a microscope or lighted magnifier to record the appearance of the individual fibers in the crime scene swatch. Record in data table # 2.
  5. Use a magnifier to count fibers in the swatch- record to data table #3.

Observations: DATA TABLE #1

 

black line

Before

Appearance    UV lamp

After Dying

Appearance    UV lamp

Acetate

 

 

 

SEF

 

 

Arnel

 

 

Bleached cotton

 

 

Creslan61

 

 

Dacron 54

 

 

Dacron64

 

 

Nylon6.6

 

 

Orlon75

 

 

Spun Silk

 

 

Polypropylene

 

 

Viscose

 

 

Wool

 

 

DATA TABLE #2

 

 

Swatch Before dye

Swatch after dye

 

 

 

 
       

Data Table #3

 

thread count warp

thread count weft

Questioned swatch

 

 

Known swatch

 

 

 

Conclusion Questions (COMPLETE SENTENCES)

  1. What are the similarities you noted between the various fibers? Explain.

 

  1. Were there any differences between natural and synthetic fibers?

 

 

  1. What is the identity of the crime scene fabric fiber? What tests results are evidence of this comparison and identification?